Manufacture of nitric acid by Ostwald’s process

Principle :

 1. Catalytic oxidation of NH₃ to NO : When ammonia is oxidized with oxygen in presence of catalyst platinum and rhodium in 9 : 1 ratio at about 800⁰C and 5 atmospheric pressure, nitric oxide is formed.

 2. Oxidation of NO to NO₂ : Nitric oxide is cooled to about 50⁰C to 100⁰C and air oxidized to nitrogen dioxide.

 3. Oxidation of nitrogen dioxide(NO₂) to nitric acid in presence of air and water.

Working of the plant or process :

The working of the plant involves following steps :

 1. Catalyst converter : Ammonia gas and air in the ratio of 1:8 by volume is first compressed and passed through converter where ammonia is oxidized into nitric oxide in the presence of platinum as catalyst at temperature 800⁰C.

 2. Cooler : The nitric oxide formed is cooled using refrigerator. The cooled nitric oxide is passed in oxidation chamber.

 3. Oxidation chamber : In this chamber, nitric oxide combines with oxygen to form nitrogen dioxide.

 4. Absorption tower : In absorption tower water is sprayed from its roof and tower is packed with acid proof(resistant) flint (stone). Here, nitrogen dioxide and oxygen {present in air} react with water to form nitric acid.

Thus obtained nitric acid is about 60% concentrated. On distillation, {nitric acid vaporize first, i.e. b.pt. 86⁰C)} the concentration of nitric acid can be increased upto 68%. This is the commercial nitric acid available.

{68% nitric acid forms azeotropic mixture(constant boiling mixture) with water. }

Preparation of 98% nitric acid : For the preparation of conc. HNO₃, it is treated with conc. H₂SO₄, which acts as dehydrating agent. So it absorbs water molecules strongly. The resulting mixture is distilled where nitric acid vaporizes first{ b.pt. 86⁰C}. The vapour is condensed to form 98% nitric acid.{ This form of nitric acid is further crystallized at -42⁰C which is separated and melted to get conc. HNO₃.}

Fuming nitric acid : when some starch solution is kept in conc. (98%) HNO3, conc. HNO3 decomposes into nitrogen dioxide (NO2) forming fume. This form of nitric acid is fuming nitric acid. Fuming nitric acid is stronger oxidizing agent than conc. HNO3.

Physical properties of nitric acid :

 1. It is colourless and odourless liquid. But on long storage, sometimes yellowish colour is seen due to slight decomposition into NO₂ ( and O₂).

 2. It is soluble in water. { 68% nitric acid forms a constant boiling mixture which is termed as azeotropic mixture.}

 3. Nitric acid is corrosive to skin.

 4. Melting point of nitric acid is -42⁰C and its boiling point is 86⁰C.

Chemical Properties of nitric acid (HNO₃)

 1. Decomposition (dissociation) of nitric acid :

In presence of sunlight, nitric acid slightly decomposes and solution turns slightly to yellow or brown due to formation of NO₂ (nitrogen dioxide) .

Concentrated nitric acid decomposes on heating. At higher temperature, the decomposition is rapid.

 2. Acidic nature :

{It changes : blue litmus to red, phenolphthalein- colourless, methyl orange- pink}

• Nitric acid is monobasic acid. It completely dissociates in water:

• It reacts with basic hydroxides, oxides,{ carbonates, ammonia,} etc to give salt and water.

• Mg and Mn reacts with very dilute nitric acid to produce hydrogen gas.

 3. Oxidizing property of nitric acid :

Nitric acid acts as strong oxidizing agent at it’s all concentration. The reactivity and products in chemical reaction involving acid depends upon the following factors:

 i. Concentration of nitric acid

 ii. Reactivity of metal

 iii. Temperature

i.  Concentration of acid : Higher the concentration of nitric acid, higher will be the oxidation state of product formed. These reduced products are formed in general :

 ii. Reactivity of metals : Metals which are more electropositive than hydrogen react with HNO3 to produce nascent hydrogen and metals which are less electropositive than hydrogen react with HNO3 to produce nascent oxygen.

Electrochemical series : The series of various elements obtained by arranging the elements in their increasing order of standard reduction potential in the vertical column is called electrochemical series.

Nascent hydrogen formation theory :

Nascent oxygen formation theory :

 iii. Temperature : The increase in temperature of the reactant increases the rate of the reaction .

A. Oxidation of metals more electropositive than hydrogen :-

→ According to nascent hydrogen formation theory.

 1. Action with zinc :

• With conc. HNO₃ :

• With moderately conc (1:1) HNO₃ :

• With dilute HNO₃ :

• With very dilute HNO₃ :

 2. Action with magnesium :

• With conc. HNO₃ :

• With moderately conc and dilute HNO₃ :

• With very dilute HNO₃ :

 3. Action with iron :

• With hot and conc. HNO₃ : When a highly conc. HNO₃ is added on Fe, a protective layer of ferrosoferric oxide (Fe₃O₄) is formed and the iron becomes passive i.e. prevents the further action of acid on the iron metal.

• With moderately conc.(1:1) HNO₃ : Fe gives ferric salt and NO₂ gas.

• With very dilute HNO₃ : Fe gives ferrous salt and NH₄NO₃

B. Oxidation of metals less electropositive than hydrogen :

→ According to nascent oxygen formation theory.

 1. Action with copper :

• With conc. HNO₃ :

• With moderately conc. or dilute HNO₃ :

 2. Action with mercury :

• With conc. HNO₃ : Hg gives mercuric salt and NO₂

• With moderately conc. or dilute HNO₃ : Hg gives mercurous salt and NO.

C. Reaction of HNO₃ with non-metals :

Dilute HNO₃ has no action with non-metals and metalloids {eg. As, Sb, etc}. Conc. HNO₃ oxidizes non-metals like carbon, sulphur, phosphorus, iodine, etc into their oxides or oxyacids and itself gets reduced to NO₂.

 1. With carbon : Carbon is oxidized to CO₂.

 2. With sulphur : sulphur is oxidized to sulphuric acid.

 3. With phosphorus : Phosphorus is oxidized to phosphoric acid.

 4. With iodine : Iodine is oxidized to iodic acid.

D. Reaction of HNO₃ with inorganic compounds (reducing agents) like H₂S, SO₂, HI, HBr, FeSO₄, etc.

 1. Conc. HNO₃ oxidizes H₂S to S.

 2. Conc. HNO₃ oxidizes KI to I₂ .

 3. Conc. HNO₃ oxidizes SO₂ to H₂SO₄ .

Action with FeSO₄ : ( Test for nitric acid or nitrate ion (NO₃^– ) :

Presence of nitric acid ( or nitrate ion ) in solution can be detected by ring test in wet test analysis. In laboratory, about 1 ml of sample solution is taken and its double volume of concentrated sulphuric acid is added (cautiously). The solution is cooled and few ml of freshly prepared ferrous sulphate solution is added from the side of test tube. Formation of brown ring between two layers of liquid indicates the presence of nitric acid ( or nitrate ).

Here, nitric acid (or nitrate ) reacts with conc. H₂SO₄ and ferrous sulphate to form ferric sulphate. Some ferrous sulphate molecules absorb nitric oxide from the solution and form nitrosyl ferrous sulphate which forms brown ring between two layers of liquid.

Chemical reaction of nitric acid with noble metals in presence of conc. HCl :

Noble metals like gold (Au), platinum (Pt), palladium (Pd), etc. neither react with conc. nitric acid nor with conc. hydrochloric acid. But these noble metals get dissolved in a mixture of conc. HNO₃ and conc. HCl in 1 : 3 ratio by volume. This mixture is called aqua- regia { Aqua= water, regia = king,i.e. kingly water} .

Aqua- regia dissolves such metals due to formation of highly reactive nascent chlorine.

Eg. reaction of gold:

Structure of nitric acid (HNO₃)

Uses of nitric acid :

• It is used in the manufacture of fertilizers, dyes and drugs.
• Used to manufacture explosive like TNT ( trinitro toluene),nitro glycerin etc.
• Used in the purification of gold and silver.
• Used as oxidizing and nitrating reagent in the laboratory.

References :

• Lee, j. D., Concise Inorganic Chemistry, Fifth Edition, Joh, Wiley and Sons, Inc., 2007.
• Sarkar, R., General and Inorganic Chemistry, Second Edition, New Central Book Agency(P) Ltd., India, 2007.
• Shriver, D. F., Atkins, P. W., Inorganic Chemistry, Fifth Edition, Oxford university Press, 2010.
• Agrawal, S. K., Lal, K., Advanced Inorganic Chemistry, Fifth Revised Edition, Pragati Prakashan, Meerut, 2001.
• Cotton, F. A., and Wilkinson, G., Advanced Inorganic Chemistry, Fifth edition, John Wily and Sons, Singapore, 1995.
• https://www.tandfonline.com/doi/pdf/10.1080/00022470.1964.10468252
• https://doubtnut.com/question-answer-chemistry/draw-the-lewis-structure-of-nitric-acid-hno3-12973480
• https://en.wikipedia.org/wiki/Ostwald_process

The post Nitric acid (HNO3) : Manufacture by Ostwald’s process,Reactions, Test, Structure and Uses appeared first on Online Chemistry notes.

Preparation of carbon monoxide (CO) :

 1. Carbon monoxide can be prepared by burning carbon with oxygen in limited supply of air.

2. It can also be prepared by reduction of metallic oxide with carbon ( i.e. coal or coke)

3. By passing steam over red hot coke.

Laboratory preparation of carbon monoxide(CO) gas :

Carbon monoxide gas can be prepared in lab by heating formic acid or oxalic acid with conc. H₂SO₄.

Procedure: Small amount of oxalic acid crystal is taken in a round- bottomed flask and all the apparatus are fitted as shown in figure. When conc. H₂SO₄ is poured in the flask through thistle funnel and heated then a mixture of CO and CO₂ gas is formed. The mixture of gas is passed through a bottle containing NaOH solution where the CO₂ gas is absorbed by NaOH.

2NaOH + CO₂ → Na₂CO₃ + H₂O

The pure CO gas is then collected in a gas jar by downward displacement of water.

Physical properties :

1. It is colourless and poisonous gas (with faint smell).
2. It is lighter than air.
3. It is slightly soluble in water.

Chemical Properties of carbon monoxide(CO):

1. It is neutral to litmus.

2. Combustibility (Reaction with oxygen) : It is combustible but not a supporter of combustion. It burns in air to form carbon dioxide.

3. Formation of addition products :

• Action with hydrogen : When carbon monoxide gas is heated with hydrogen in presence of ZnO and Cu at 300⁰C then methanol is formed.

• Action with NaOH ( caustic soda): When carbon monoxide is heated with sodium hydroxide then sodium formate is formed.

   {note: CO2  + NaOH → Na2CO3 + H2O}

• Action with chlorine: Carbon monoxide reacts with chlorine in presence of sunlight to produce phosgene ( carbonyl chloride) which is a poisonous gas.

• Action with sulphur : When a mixture of carbon monoxide and sulphur vapour is heated, then carbonyl sulphide is formed.

         CO + S → COS (carbonyl sulphide)

• Action with ammonical cuprous chloride (solution) : When carbon monoxide gas is passed into ammonical cuprous chloride solution, an addition product i.e. cuprous carbonyl chloride is obtained.

 4. Reaction with transition metals ( i.e. Formation of carbonyl compound) :

Carbon monoxide reacts with transition metals like nickel, iron, cobalt, etc. under suitable conditions to form addition compound called metal carbonyls.

Eg. When CO gas is passed into finely divided nickel at 80⁰C, then nickel tetracarbonyl is formed.

Similarly,

{Carbonyl compound formation takes place due to presence of lone pair of electron in carbon atom of CO molecule, i.e. a Lewis base}

5. Reducing character : Carbon monoxide acts as reducing agent.

• It is used to reduce metallic oxide to metal in metallurgical process. Eg.

• It can reduce iodine oxide to iodine.

• Reduction of Tollen’s reagent( i.e. ammonical silver nitrate solution) : It reduces Tollen’s reagent to metallic silver.

• Reduction of Fehling’s solution : {Basic copper sulphate solution in presence of sodium potassium tartarate is called Fehling’s solution.} It reduces Fehling’s solution to red ppt. of cuprous oxide.

Uses of CO :

1. It is used as reducing agent in metallurgical process.
2. It is used to prepare carbonyl compounds.
3. It is used to prepare poisonous gas.

Structure of carbon monoxide(CO)

Carbon monoxide toxicity :

Q) Why carbon monoxide gas is extremely poisonous( toxic) ?

→ Carbon monoxide combines with haemoglobin to form carboxy haemoglobin. This makes haemoglobin unable to carry oxygen from lungs to the different parts of the body and causes suffocation and even death. Thus CO gas is highly toxic.

{ Therefore, it is adviced that a room being heated by burning coal or other carbon rich fuel should be well ventilated.}

Some questions and answers :

Q) Carbon monoxide is used as a reducing agent in metallurgy but not carbon dioxide, why?

→ CO reduces other substance and itself oxidizes to form CO₂ but CO₂ already is oxidized form and can not further reduce other species. So, CO is used as reducing agent but not CO₂.

Q) How would you convert CO into CO₂ and vice versa ?

→ CO can be converted into CO₂ by heating in the presenc of excess of air.

CO₂ can be converted into CO by passing through red hot coke.

Q) Write down balanced chemical equations giving proper products for the following statements :

i. Water gas is heated over ZnO + Cu.

ii. Carbon monoxide is passed over heated caustic soda.

→ i.

   ii)

Additional Questions from carbon :

Q) What is dry ice? Why it is called so?

→ Solid CO₂ is called dry ice because its structure is similar to that of ice. When it is kept for some time then it gets evaporated without wetting the place where it is kept.

Q) How can you prove that all the allotropes of carbon contain same element?

Q) Show that diamond and graphite consist of carbon only.

→ To prove it first of all 1 gm sample of each allotropes of carbon is taken in a combustion tube and burnt with oxygen to form carbondioxide . The carbondioxide formed is passed into calculated amount of NaOH solution. In all cases the weight of NaOH solution increases. This proves all the allotropes of carbon contains same element.

References :

• Shriver, D. F., Atkins, P. W., Inorganic Chemistry, Fifth Edition, Oxford university Press, 2010.
• Agrawal, S. K., Lal, K., Advanced Inorganic Chemistry, Fifth Revised Edition, Pragati Prakashan, Meerut, 2001.
• Cotton, F. A., and Wilkinson, G., Advanced Inorganic Chemistry, Fifth edition, John Wily and Sons, Singapore, 1995.
• Day, C.M., Selbin, J., Theoritical inorganic Chemistry, second edition, Affiliated East-West Press Pvt. Ltd., New Delhi, 2002.
• https://www.medicalnewstoday.com/articles/171876
• https://www.simply.science/images/content/chemistry/metals_and_non_metals/carbon_family/conceptmap/Carbon_Monoxide.html

The post Carbon monoxide (CO) : Preparation, Properties, Structure and Poisoning. appeared first on Online Chemistry notes.

Hydrogen sulphide (H₂S) gas is prepared in the laboratory by treating iron sulphide with dil. H₂SO₄.

Procedure : Iron sulphide (FeS) pieces are kept in woulf’s bottle. Then a thistle funnel and delivery tube is fitted as shown in fig. When dilute H₂SO₄ is poured in woulf ’s bottle, reaction between FeS and dil. H₂SO₄ takes place and H₂S gas is evolved which is collected in the gas jar by upward displacement of air.

Test of H₂S : When a lead acetate paper is dipped in the jar containing H₂S gas, it turns to black due to formation of lead sulphide.

Intermittent supply of H₂S gas by Kipp’s apparatus :

(Working principle of Kipp’s apparatus )

{Intermittent = Stopping and starting at irregular intervals}

H₂S gas is frequently required for salt analysis in the laboratory. The special apparatus which is used for the preparation of H₂S is called Kipp’s apparatus.

Kipp’s apparatus consist of three bulbs A, B and C. The bulbs are interconnected with each other. The upper bulb C contains a long stem which reaches upto bulb A. When dil. H₂SO₄ is poured from bulb C, liquid level rises in bulb A and reaches upto bulb B just to cover iron sulphide. Then the reaction between iron sulphide and H₂SO₄ takes place to form H₂S gas. As H₂S gas is formed, the pressure inside bulb B increases and forces the dil. H₂SO₄ up into the upper bulb C. Then the contact between FeS and dil. H₂SO₄ breaks and the formation of gas is stopped (ceased). When the tap is opened H₂S comes out and the pressure decreases. As a result liquid level again rises at bulb B and H₂S gas start to evolve again. In this way H₂S gas is prepared intermittently by Kipp’s apparatus.

Physical Properties of H₂S :

1. It is colourless gas with rotten egg smell.
2. It is soluble in water.
3. It is poisonous gas.

   {In its low concentration it causes nausea, dizziness and headache. At high concentration it is fatal (i.e. deadly poisonous). Conc. of H2S in air 1 part in 1000 parts of air may be fatal.}

4. It is heavier than air{with vapour density 17}

Chemical Properties of H₂S :

 1. Acidic character of H₂S :

It acts as a weak diprotic (dibasic) acid. It ionizes in two steps to give two protons.

• H₂S reacts with base to form two series of salts. Eg.

• H₂S reacts with basic oxides to give salt.

2. H₂S as reducing agent :-

Sulphur in H₂S bears -2 oxidation state which in minimum oxidation state of sulphur. In chemical reaction, H₂S tends to get oxidized . So H₂S acts as reducing agent.

• It reduces halogens into halogen acids.

• It reduces sulphur dioxide to sulphur.

• It reduces ferric salt to ferrous salt.

• It reduces conc. HNO₃ to NO_2.

• It reduces conc. H₂SO₄ to SO₂.

• It reduces acidified potassium permanganate solution and pink colour of KMnO₄ is discharged.

• It reduces acidified K₂Cr₂O₇ solution and orange color of K₂Cr₂O₇ changes to green.

3. H₂S as analytical reagent in salt analysis ( Precipitation of metal sulphide) :

H₂S gas is used as analytical agent to detect group II basic radicals in acidic medium i.e. HCl and group IIIB basic radicals in in alkaline medium i.e. NH₄Cl and NH₄OH.

Group II basic radicals : Group II basic radicals consists of Cu ⁺⁺ , Hg ⁺⁺, Pb⁺⁺, Cd⁺⁺, Sn⁺⁺, As⁺⁺⁺, Sb⁺⁺⁺, Bi⁺⁺⁺. In qualitative salt analysis this group II radicals are precipitated in the form of their sulphide in acidic medium. By noting the colour of ppt., we can identify the metal cations.

Group IIIB basic radicals : Group IIIB basic radicals consist of Zn⁺⁺, Co⁺⁺, Ni⁺⁺, Mn⁺⁺. These are precipitated by passing H₂S in alkaline medium ( i.e. NH₄Cl + NH₄OH).

Structure of H₂S :

Uses of Hydrogen sulphide (H₂S) :

• It is used as analytical reagent in laboratory.
• It is used as reducing agent.
• It is used to prepare metallic sulphide, which can be used as pigment.

References :

• Shriver, D. F., Atkins, P. W., Inorganic Chemistry, Fifth Edition, Oxford university Press, 2010.
• Agrawal, S. K., Lal, K., Advanced Inorganic Chemistry, Fifth Revised Edition, Pragati Prakashan, Meerut, 2001.
• Cotton, F. A., and Wilkinson, G., Advanced Inorganic Chemistry, Fifth edition, John Wily and Sons, Singapore, 1995.
• Day, C.M., Selbin, J., Theoritical inorganic Chemistry, second edition, Affiliated East-West Press Pvt. Ltd., New Delhi, 2002.
• Mitra, L.A. , A Text Book of Inorganic Chemistry, Ghos and Company, 61^st edition, 1996.
• https://en.wikipedia.org/wiki/Kipp%27s_apparatus
• https://www2.humboldt.edu/scimus/HSC.54-70/Descriptions/Kipp%27sGasApp.htm

The post Hydrogen sulphide (H2S): Lab preparation, Kipp’s apparatus, Properties and Uses. appeared first on Online Chemistry notes.

Preparation of Sulphur dioxide:

• By burning sulphur in air.

• By roasting metal sulphide : When metal sulphides (sulphide ores) are heated in excess of air at high temperature, then SO₂ gas is produced.

Laboratory preparation of sulphur dioxide (SO₂) :

Sulphur dioxide gas is prepared in laboratory by heating copper turnings with conc. H₂SO₄.

Procedure: Copper turnings are taken in a round bottom flask fitted with thistle funnel and delivery tube as shown in figure. When conc. H₂SO₄ is poured through thistle funnel and mixture is heated sulphur dioxide gas is evolved, which is collected in the gas jar by upward displacement of air.

Drying of SO₂:  If sulphur dioxide gas is to be dried, the gas obtained is passed through conc. Sulphuric acid . The moisture is absorbed by conc. H₂SO₄.

Chemical Properties of sulphur dioxide (SO₂)

1. Weak acidic nature of SO₂ :

It dissolves in water to give sulphurous acid, a weak diprotic (dibasic) acid.

Sulphurous acid ionizes in two steps:

It produces two series of salts if reacted with base.Eg.

2. SO₂ as a reducing agent :

Aqueous sulphurdioxide shows reducing character and SO₂ itself gets oxidized to H₂SO₄.

• It reduces halogens (Cl₂, Br₂, I₂) in aq. Solution to respective halides. Eg.

• It reduces acidified potassium permanganate solution and pink colour of KMnO₄ is discharged.

• It reduces acidified K₂Cr₂O₇ solution and orange color of K₂Cr₂O₇ changes to light green.

• It reduces ferric salt to ferrous salt and colour changes from yellow to light green.

• It reduces potassium iodate(KIO₃) solution to iodine.

3. SO₂ as an oxidizing agent :

SO₂ oxidizes powerful reducing agents like H₂S, HI, Mg, Fe, etc and itself get reduced to sulphur or sulphide.

4. SO₂ as a bleaching agent:

Formation of colourless product from coloured substance is called bleaching. Chemical substances such as SO2, H2O2, CaOCl2, Cl2, etc. show bleaching action.

SO₂ can act a a bleaching agent in presence of moisture. It can bleach coloured wool, silk, flower, hair, etc. The bleaching action of sulphur dioxide is due to the formation of nascent hydrogen in presence of moisture, which reduces colouring substance to colourless reduced product.

In some cases, bleaching action of SO₂ is due to formation of colourless addition product.

→ The bleaching action of SO₂ is temporary. The bleached colourless compound will regain its original colour slowly on standing in air due to oxidation by air.

Comparison of bleaching action of SO₂ and Cl₂:

Test for sulphur dioxide (SO₂) :

• Odour : Sulphur dioxide has typical suffocating smell of burning sulphur.
• Potassium dichromate paper test : When SO₂ comes in contact with acidified potassium dichromate paper, the orange coloured paper turns to green due to formation of chromium sulphate.

Uses of SO₂

• It is used as bleaching agent.
• It is used in the manufacture of sulphuric acid.
• It can be used as disinfectant, fungicide and food preservative.

References :

• Sarkar, R., General and Inorganic Chemistry, Second Edition, New Central Book Agency(P) Ltd., India, 2007.
• Shriver, D. F., Atkins, P. W., Inorganic Chemistry, Fifth Edition, Oxford university Press, 2010.
• Agrawal, S. K., Lal, K., Advanced Inorganic Chemistry, Fifth Revised Edition, Pragati Prakashan, Meerut, 2001.
• Cotton, F. A., and Wilkinson, G., Advanced Inorganic Chemistry, Fifth edition, John Wily and Sons, Singapore, 1995.
• https://www.environment.gov.au/protection/publications/factsheet-sulfur-dioxide-so2
• https://en.wikipedia.org/wiki/Sulfur_dioxide

The post Sulphur dioxide (SO2) : Preparation, Properties and Uses. appeared first on Online Chemistry notes.

New syllabus (curriculam) of class 11 and 12 chemistry for NEB board Nepal..

Class – 11 Chemistry Syllabus(Nepal)

Subject code        : 201

Total working hours : 160 hours.

Theory              : 128 teaching hours.

Practical           : 32 teaching hours.

Final exam          : 100 marks- Out of 100, 75 from theoretical exam and 25 from practical exam+ viva ,records, project works and internal exams.

General and Physical Chemistry : 48 teaching hours.

Unit -1 . Foundation and Fundamentals : 2 teaching hours

General introduction of chemistry, Importance and scope of chemistry, Basic concepts of chemistry (atoms, molecules, relative masses of atoms and molecules, atomic mass unit ( amu), radicals, molecular formula, empirical formula ), Percentage composition from molecular formula.

Unit -2 . Stoichiometry : 8 teaching hours

Dalton’s atomic theory and its postulates , Laws of stoichiometry, Avogadro’s law and some deductions ( Molecular mass and vapour density , Molecular mass and volume of gas, Molecular mass and no. of particles) , Mole and its relation with mass, volume and number of particles; Calculations based on mole concept ; Limiting reactant and excess reactant ;Theoretical yield, experimental yield and % yield ; Calculation of empirical and molecular formula from % composition (Solving related numerical problems)

Unit -3 . Atomic Structure :        8 teaching hours

Rutherford’s atomic model ; Limitations of Rutherford’s atomic model; Postulates of Bohr’s atomic model and its application ; Spectrum of hydrogen atom ; Defects of Bohr’s theory; Elementary idea of quantum mechanical model: de Broglie’s wave equation; Heisenberg’s Uncertainty Principle ; Concept of probability; Quantum Numbers ; Orbitals and shape of s and p orbitals only; Aufbau Principle; Pauli’s exclusion principle; Hund’s rule and electronic configurations of atoms and ions (up to atomic no. 30)

Unit-4. Classification of elements and Periodic Table: 5 teaching hours

Modern periodic law and modern periodic table; Classification of elements into different groups, periods and blocks ; IUPAC classification of elements; Nuclear charge and effective nuclear charge ;Periodic trend and periodicity : Atomic radii ,Ionic radii , Ionization energy , Electron affinity ,Electronegativity , Metallic characters (General trend and explanation only)

Unit-5. Chemical Bonding and Shapes of Molecules : 9 teaching hours

Valence shell, valence electron and octet theory ; Ionic bond and its properties ; Covalent bond and coordinate covalent bond ;Properties of covalent compounds ; Lewis dot structure of some common compounds of s and p block elements ; Resonance ;VSEPR theory and shapes of some simple molecules (BeF₂, BF₃, CH₄, CH₃Cl, PCl₅, SF₆, H₂O,NH₃,CO₂,H₂S, PH₃); Elementary idea of Valence Bond Theory; Hybridization involving s and p orbitals only ; Bond characteristics: Bond length, Ionic character, Dipole moment; Vander Waal’s force and molecular solids ; Hydrogen bonding and its application; Metallic bonding and properties of metallic solids

Unit-6. Oxidation and Reduction : 5 teaching hours

General and electronic concept of oxidation and reduction; Oxidation number and rules for assigning oxidation number ; Balancing redox reactions by oxidation number and ion-electron (half reaction) method ; Electrolysis : Qualitative aspect and Quantitative aspect(Faradays laws of electrolysis)

Unit-7. States of Matter :       8 teaching hours

7.1 Gaseous state : Kinetic theory of gas and its postulates ;Gas laws -Boyle’s law and Charles’ law, Avogadro’s law ;Combined gas equation ;Dalton’s law of partial pressure ;Graham’s law of diffusion; Ideal gas and ideal gas equation ; Universal gas constant and its significance; Deviation of real gas from ideality (Solving related numerical problems based on gas laws)

7.2 Liquid state : Physical properties of liquids- Evaporation and condensation ,Vapour pressure and boiling point ,Surface tension and viscosity (qualitative idea only) ; Liquid crystals and their applications

7.3 Solid state : Types of solids -Amorphous and crystalline solids, Efflorescent, Deliquescent and Hygroscopic solids ; Crystallization and crystal growth; Water of crystallization; Introduction to unit crystal lattice and unit cell .

Unit-8. Chemical equilibrium:       3 teaching hours

Physical and chemical equilibrium; Dynamic nature of chemical equilibrium; Law of mass action; Expression for equilibrium constant and its importance; Relationship between Kp and Kc ; Le Chatelier’s Principle (Numericals not required)

Inorganic Chemistry : 35 teaching hours

Unit-9. Chemistry of Non-metal :

9.1. Hydrogen, Oxygen and ozone : 4 teaching hours

9.1.1 Hydrogen : Chemistry of atomic and nascent hydrogen ; Isotopes of hydrogen and their uses; Application of hydrogen as fuel ; Heavy water and its applications

9.1.2 Oxygen : Allotropes of Oxygen – Definition of allotropy and examples; Types of oxides (acidic, basic, neutral, amphoteric, peroxide and mixed oxides) ; Applications of hydrogen peroxide; Medical and industrial application of oxygen

9.1.3 Ozone: Occurrence ; Preparation of ozone from oxygen; Structure of ozone; Test for ozone; Ozone layer depletion (causes, effects and control measures) ; Uses of ozone

9.2 Nitrogen :       5 teaching hours

Reason for inertness of nitrogen and active nitrogen ; Chemical properties of ammonia [ Action with CuSO₄ solution, water, FeCl₃ solution, Conc. HCl, Mercurous nitrate paper, O₂ ]; Applications of ammonia; Harmful effects of ammonia ; Oxy-acids of nitrogen (name andformula); Chemical properties of nitric acid [HNO₃ as an acid and oxidizing agent (action with zinc, magnesium, iron, copper, sulphur, carbon, SO₂ and H₂S) ; Ring test for nitrate ion.

9.3 Halogens:       5 teaching hours

General characteristics of halogens; Comparative study on preparation (no diagram and description is required); Chemical properties [with water, alkali, ammonia, oxidizing character, bleaching action] and uses of halogens (Cl₂, Br₂ and I₂); Test for Cl₂, Br₂ and I2 ; Comparative study on preparation (no diagram and description is required), properties ( reducing strength, acidic nature and solubility) and uses of haloacids (HCl, HBr and HI)

9.4 Carbon and Phosphorus :    3 teaching hours

9.4.1 Carbon : Allotropes of carbon (crystalline and amorphous) including fullerenes (structure, general properties and uses only) ; Properties (reducing action, reaction with metals and nonmetals) and uses of carbon monoxide

9.4.2 Phosphorus : Allotropes of phosphorus (name only); Preparation (no diagram and description is required), properties ( basic nature ,reducing nature , action with halogens and oxygen) and uses of phosphine.

9.5 Sulphur :       5 teaching hours

Allotropes of sulphur (name only) and uses of sulphur ; Hydrogen sulphide (preparation from Kipp’s apparatus with diagram,) properties (Acidic nature, reducing nature, analytical reagent) and uses ; Sulphur dioxide its properties (acidic nature, reducing nature, oxidising nature and bleaching action) and uses ; Sulphuric acid and its properties (acidic nature, oxidising nature, dehydrating nature) and uses ; Sodium thiosulphate (formula and uses) .

Unit-10. Chemistry of Metals

10.1 Metals and Metallurgical Principles : 5 teaching hours

Definition of metallurgy and its types (hydrometallurgy, pyrometallurgy, electrometallurgy) ; Introduction of ores ; Gangue or matrix, flux and slag, alloy and amalgam ; General principles of extraction of metals (different processes involved in metallurgy) – concentration, calcination and roasting, smelting, carbon reduction, thermite and electrochemical reduction ; Refining of metals (poling and electro-refinement)

10.2 Alkali and Alkaline earth Metals : 5 teaching hours

10.2.1 Alkali Metals : General characteristics of alkali metals ; Sodium [extraction from Down’s process, properties (action with Oxygen, water, acids nonmetals and ammonia) and uses] ; Properties (precipitation reaction and action with carbon monooxide) and uses of sodium hydroxide ; Properties (action with CO2, SO2, water, precipitation reactions) and uses of sodium carbonate

10.2.2 Alkaline Earth Metals : General characteristics of alkaline earth metals ; Molecular formula and uses of (quick lime, bleaching powder, magnesia, plaster of paris and epsom salt); Solubility of hydroxides, carbonates and sulphates of alkaline earth metals (general trend with explanation) ; Stability of carbonate and nitrate of alkaline earth metals (general trend with explanation).

Unit- 11. Bio-inorganic Chemistry : 3 teaching hours

Introduction to Bio-inorganic Chemistry ; Introduction of Micro and macro nutrients ; Importance of metal ions in biological systems (ions of Na, K, Mg, Ca, Fe, Cu, Zn, Ni, Co, Cr) ; Ion pumps (sodium-potassium and sodium-glucose pump) 11.5 Metal toxicity (toxicity due to iron, arsenic, mercury, lead and cadmium)

Organic Chemistry : 30 teaching hours

Unit- 12. Basic Concept of Organic Chemistry : 6 teaching hours

Introduction to organic chemistry and organic compounds ; Reasons for the separate study of organic compounds from inorganic compounds ; Tetra-covalency and catenation properties of carbon ; Classification of organic compounds ; Alkyl groups, functional groups and homologous series ; Idea of structural formula, contracted formula and bond line structural formula ; Preliminary idea of cracking and reforming, quality of gasoline, octane number, cetane number and gasoline additive

Unit 13. Fundamental Principles of Organic Chemistry : 10 teaching hours

IUPAC Nomenclature of Organic Compounds (upto chain having 6 carbon atoms) ; Qualitative analysis of organic compounds (detection of N, S and halogens by Lassaigne’s test) ; Isomerism in Organic Compounds ; Definition and classification of isomerism ; Structural isomerism and its types: chain isomerism, position isomerism, functional isomerism, metamerism and tautomerism ; Concept of geometrical isomerism (cis & trans) & optical isomerism (d & l form)

Preliminary Idea of Reaction Mechanism : Homolytic and heterolytic fission ; Electrophiles, nucleophiles and free- radicals ; Inductive effect: +I and –I effect ; Resonance effect: +R and –R effect .

Unit 14. Hydrocarbons : 8 teaching hours

14.1 Saturated Hydrocarbons (Alkanes): Preparation from haloalkanes (Reduction and Wurtz reaction), Decarboxylation, Catalytic hydrogenation of alkene and alkyne ; Chemical properties: Substitution reactions (halogenation, nitration & sulphonation only), oxidation of ethane ; Unsaturated hydrocarbons (Alkenes & Alkynes) .

14.2 Alkenes: Preparation by Dehydration of alcohol, Dehydrohalogenation, Catalytic hydrogenation of alkyne ; Chemical properties: Addition reaction with HX (Markovnikov’s addition and peroxide effect), H₂O, O₃, H₂SO₄ only

14.3 Alkynes: Preparation from carbon and hydrogen, 1,2 dibromoethane, chloroform/iodoform only ; Chemical properties: Addition reaction with (H₂, HX, H₂O), Acidic nature (action with Sodium, ammoniacal AgNO₃ and ammoniacal Cu₂Cl₂) ; Test of unsaturation (ethene & ethyne): bromine water test and Baeyer’s test ;

14.4 Comparative studies of physical properties of alkane, alkene and alkyne; Kolbe’s electrolysis methods for the preparation of alkane, alkene and alkynes

Unit 15. Aromatic Hydrocarbons : 6 teaching hours

Introduction and characteristics of aromatic compounds : Huckel’s rule of aromaticity : Kekule structure of benzene : Resonance and isomerism : Preparation of benzene from decarboxylation of sodium benzoate, phenol, and ethyne only ; Physical properties of benzene ; Chemical properties of benzene: Addition reaction: hydrogen, halogen, Electrophilic substitution reactions: orientation of benzene derivatives (o, m & p), nitration, sulphonation, halogenations, Friedal-Craft’s reaction (alkylation and acylation), combustion of benzene ( free combustion only) and uses.

Applied Chemistry : 15 teaching hours

Unit: 16 Fundamentals of Applied Chemistry : 4 teaching hours

Fundamentals of Applied Chemistry ; Chemical industry and its importance ; Stages in producing a new product ; Economics of production ; Cash flow in the production cycle ; Running a chemical plant; Designing a chemical plant ; Continuous and batch processing ; Environmental impact of the chemical industry.

Unit: 17 Modern Chemical Manufactures : 11 teaching hours

Modern Chemical Manufactures (principle and flow sheet diagram only) ; Manufacture of ammonia by Haber’s process ; Manufacture of nitric acid by Ostwald’s process ; Manufacture of sulphuric acid by contact process ; Manufacture of sodium hydroxide by Diaphragm Cell ; Manufacture of sodium carbonate by ammonia soda or Solvay process ; Fertilizers (Chemical fertilizers, types of chemical fertilizers, production of urea with flow-sheet diagram)

Class- 12 Chemistry syllabus(Nepal)

Subject code        : 202

Total working hours : 160 hours.

Theory              : 128 teaching hours.

Practical           : 32 teaching hours.

Final exam mark     : 100 marks- Out of 100, 75 from theoretical exam and 25 from practical exam+ viva ,records, project works and internal exams.

Physical Chemistry:     40 teaching hours

Unit-1. Volumetric Analysis     :  8 teaching hrs

Introduction to gravimetric analysis, volumetric analysis and equivalent weight ; Relationship between equivalent weight, atomic weight and valency ; Equivalent weight of compounds (acid, base, salt, oxidizing and reducing agents) ; Concentration of solution and its units in terms of : Percentage, g/L , molarity, molality, normality and formality, ppm and ppb ; Primary and secondary standard substances ; Law of equivalence and normality equation ; Titration and its types: Acid-base titration, redox titration ( related numerical problems)

Unit 2. Ionic Equilibrium :      10 hrs

Introduction to Acids and Bases ; Limitation of Arrhenius concepts of acids and bases ; Bronsted –Lowry definition of acids and bases ; Relative strength of acids and bases ; Conjugate acid –base pairs ; Lewis definition of acids and bases ; Ionization of weak electrolyte (Ostwald’s dilution law) ; Ionic product of water(Kw) ; Dissociation constant of acid and base, (Ka& Kb) ; Concept of pKa and pKb ; pH value: pH of strong and weak acids, pH of strong and weak bases ; Solubility and solubility product principle ; Common Ion effect ; Application of solubility product principle and common ion effect in precipitation reactions ; Buffer solution and its application ; Indicators and selection of indicators in acid base titration; Types of salts: Acidic salts, basic salts, simple salts, complex salts (introduction and examples) ; Hydrolysis of salts : Salts of strong acid and strong base , Salts of weak acid and strong base , Salts of weak base and strong acid (solving related numerical problems)

Unit 3. Chemical Kinetics       : 7 hrs

Introduction ; Rate of reactions: Average and instantaneous rate of reactions ; Rate law and its expressions ; Rate constant and its unit and significance; Order and molecularity ; Integrated rate equation for zero and first order reaction ; Half-life of zero and first order reactions ; Collision theory, concept of activation energy and activated complex ; Factors affecting rate of reactions: Effect of concentration, temperature (Arrhenius Equation) and effect of catalyst (energy profile diagram) ; Catalysis and types of catalysis: homogeneous, heterogeneous and enzyme catalysis (solving related numerical problems based on rate, rate constant and order of zero and first order reactions)

Unit 4. Thermodynamics       :   8 hrs

Introduction ; Energy in chemical reactions ; Internal energy ; First law of thermodynamics ; Enthalpy and enthalpy changes: Endothermic and exothermic processes) ; Enthalpy of reaction, enthalpy of solution, enthalpy of formation, enthalpy of combustion ; Laws of thermochemistry (Laplace Law and Hess’s law) ; Entropy and spontaneity ; Second law of thermodynamics ; Gibbs’ free energy and prediction of spontaneity ; Relationship between ∆G and equilibrium constant (Solving related numerical problems)

Unit 5. Electrochemistry    :   7 hrs

Electrode potential and standard electrode potential ; Types of electrodes: Standard hydrogen electrode and calomel electrodes ; Electrochemical series and its applications ; Voltaic cell: Zn-Cu cell, Ag- Cu cell ; Cell potential and standard cell potential ; Relationship between cell potential and free energy ; Commercial batteries and fuel cells (hydrogen/oxygen)

Inorganic Chemistry : 20 teaching hours.

Unit 6.Transition Metals           :   5 hrs

Introduction ; Characteristics of transition metals ; Oxidation states of transition metals ; Complex ions and metal complexes ; Shapes of complex ions ; d-orbitals in complex ions (simple explanation by crystal field theory) for octahedral complex ; Reasons for the colour of transition metal compounds ; Catalytic properties of transition metals

Unit 7. Studies of Heavy Metals        :  15 hrs

7.1 Copper : Occurrence and extraction of copper from copper pyrite ; Properties (with air, acids, aqueous ammonia and metal ions) and uses of copper ; Chemistry (preparation, properties and uses) of blue vitriol ; Other compounds of copper (red oxide and black oxide of copper) formula and uses only

7.2 Zinc : Occurrence and extraction of zinc from zinc blende ; Properties (with air, acid, alkali, displacement reaction) and uses of zinc ; Chemistry (preparation, properties and uses) of white vitriol

7.3 Mercury : Occurrence and extraction of mercury from cinnabar ; Properties of mercury ; Chemistry (preparation, properties and uses) of calomel and corrosive sublimate

7.4 Iron : Occurrence and extraction of iron ; Properties and uses of iron ; Manufacture of steel by Basic Oxygen Method and Open Hearth Process ; Corrosion of iron and its prevention

7.5 Silver : Occurrence and extraction of silver by cyanide process ; Preparation and uses of silver chloride and silver nitrate.

Organic Chemistry : 55 teaching hours.

Unit 8. Haloalkanes        :  8 hrs

Introduction ; Nomenclature, isomerism and classification of monohaloalkanes ; Preparation of monohaloalkanes from alkanes, alkenes and alcohols ; Physical properties of monohaloalkanes ; Chemical properties, substitution reactions SN1 and SN2 reactions (basic concept only) ; Formation of alcohol, nitrile, amine, ether, thioether, carbylamines, nitrite and nitro alkane using haloalkanes ; Elimination reaction (dehydrohalogenation- Saytzeff’s rule), Reduction reactions, Wurtz reaction ; Preparation of trichloromethane from ethanol and propanone ; Chemical properties of trichloromethane: oxidation, reduction, action on silver powder, conc. nitric acid, propanone, and aqueous alkali.

Unit 9. Haloarenes     : 3 hrs

Introduction ; Nomenclature and isomerism of haloarenes ; Preparation of chlorobenzene from benzene and benzene diazonium chloride ; Physical properties ; Chemical properties : Low reactivity of haloarenes as compared to haloalkanes in term of nucleophilic substitution reaction , Reduction of chlorobenzene , Electrophilic substitution reactions , Action with Na (Fittig and Wurtz- Fittig reaction) ; Action with chloral ; Uses of haloarenes.

Unit 10. Alcohols         : 7 hrs

Introduction ; Nomenclature; isomerism and classification of monohydric alcohol ; Distinction of primary, secondary and tertiary alcohols by Victor Meyer’s Method ; Preparation of monohydric alcohols from Haloalkane, primary amines, and esters ; Industrial preparation alcohol from: oxo process, hydroboration-oxidation of ethene & fermentation of sugar ; Definition of common terms: Absolute alcohol, power alcohol, denatured alcohol (methylated spirit), rectified spirit; alcoholic beverage ; Physical properties monohydric alcohols ; Chemical properties of monohydric alcohols : Reaction with HX, PX₃, PCl₅, SOCl₂ ; Action with reactive metals like Na, K, Li ; Dehydration of alcohols ; Oxidation of primary, secondary and tertiary alcohol with mild oxidizing agents like acidified KMnO₄ or K₂Cr₂O₇ ; Catalyic dehydrogenation of 1⁰ and 2⁰ alcohol and dehydration of 3⁰ alcohol. ; Esterification reaction ; Test of ethanol.

Unit 11. Phenols       : 4 hrs

Introduction and nomenclature ; Preparation of phenol from i. chlorobenzene ii. Diazonium salt and iii. benzene sulphonic acid ; Physical properties of phenol ; Chemical properties : Acidic nature of phenol (comparison with alcohol and water) ; Action with NH₃, Zn, Na, benzene diazonium chloride and phthalic anhydride ; Acylation reaction, Kolbe’s reaction, Reimer-Tiemann’s reaction ; Electrophilic substitution: nitration, sulphonation, brominaiton and Friedal-Craft’s alkylation ; Test of phenol: (FeCl3 test, aq. Bromine test & Libermann test) ; Uses of phenol .

Unit 12. Ethers        : 2 hrs

Introduction ; Nomenclature, classification and isomerism of ethers ; Preparation of aliphatic and aromatic ethers from Williamson’s synthesis ; Physical properties of ether ; Chemical properties of ethoxyethane: action with HI , Conc. HCl, Conc. H2SO₄, air and Cl₂ , Uses of ethers

Unit 13. aldehydes and Ketones      : 10 hrs

Introduction, nomenclature and isomerism ; Preparation of aldehydes and ketones from: Dehydrogenation and oxidation of alcohol, Ozonolysis of alkenes, Acid chloride, Gem dihaloalkane, Catalytic hydration of alkynes ; Physical properties of aldehydes and ketones ; Chemical properties ; Structure and nature of carbonyl group ; Distinction between aldehyde and ketones by using 2,4- DNP reagent, Tollen’s reagent, Fehling’s solution ; Addition reaction: addition of H₂, HCN and NaHSO₃ 13.1.4.4 Action of aldehyde and ketone with ammonia derivatives; NH₂OH, NH₂-NH₂, phenyl hydrazine, semicarbazide ; Aldol condensation ; Cannizzaro’s reaction ; Clemmensen’s reduction 13.1.4.8 Wolf-Kishner reduction ; Action with PCl₅ and action with LiAlH₄ ; Action of methanal with ammonia and phenol ; Formalin and its uses .

Aromatic aldehydes and Ketones : Preparation of benzaldehyde from toluene and acetophenone from benzene ; Properties of benzaldehyde ; Perkin condensation ; Benzoin condensation ; Cannizzaro’s reaction ; Electrophilic substitution reaction .

Unit 14. Carboxylic Acid and its Derivaties     : 9 hrs

Aliphatic and aromatic carboxylic acids : Introduction, nomenclature and isomerism ; Preparation of monocarboxylic acids from: aldehydes, nitriles, dicarboxylic acid, sodium alkoxide and trihaloalkanes ; Preparation of benzoic acid from alkyl benzene ; Physical properties of monocarboxylic acids ; Chemical properties: Action with alkalies, metal oxides, metal carbonates, metal bicarbonates, PCl₃, LiAlH₄ and dehydration of carboxylic acid ; Hell-Volhard-Zelinsky reaction ; Electrophilic substitution reaction of benzoic acid bromination, nitration and sulphonation) ; Effect of constituents on the acidic strength of carboxylic acid ; Abnormal behaviour of methanoic acid

Derivatives of Carboxylic acids (acid halides, amides, esters and anhydrides) : Preparation of acid derivatives from carboxylic acid ; Comparative physical properties of acid derivatives ; Comparative chemical properties of acid derivatives (hydrolysis, ammonolysis, amines (RNH₂), alcoholysis, and reduction only) ; Claisen condensation ; Hofmann bromamide reaction ; Amphoteric nature of amide ; Relative reactivity of acid derivatives.

Unit 15. Nitro Compounds        : 3 hrs

Nitroalkanes : Introduction, nomenclature and isomerism ; Preparation from haloalkane and alkane ; Physical properties ; Chemical properties: Reduction ; Nitrobenzene : Preparation from benzene ; Physical properties ; Chemical properties : Reduction in different media ; Electrophilic substitution reactions (nitration, sulphonation & bromination) ; Uses of nitro-compounds .

Unit 16. Amines      : 7 hrs

Aliphatic amines : Introduction, nomenclature, classification and isomerism ; Separation of primary, secondary and tertiary amines by Hoffmann’s method ; Preparation of primary amines from haloalkane, nitriles, nitroalkanes and amides ; Physical properties ; Chemical properties: basicity of amines, comparative study of basic nature of 1⁰, 2⁰ and 3⁰ amines ; Reaction of primary amines with chloroform, conc. HCl, R-X, RCOX and nitrous acid (NaNO₂ / HCl) ; Test of 1⁰, 2⁰ and 3⁰ amines (nitrous acid test)

Aromatic amine (Aniline) : Preparation of aniline from nitrobenzene, phenol ; Physical properties ; Chemical properties: basicity of aniline, comparison of basic nature of aniline with aliphatic amines and ammonia, alkylation, acylation, diazotization, carbylamine and coupling reaction, electrophilic substitution: Nitration sulphonation and bromination ; Uses of aniline.

Unit 17. Organometallic Compounds       : 2 hrs

Introduction, general formula and examples of organolithium, organocopper and organocadmium compounds ; Nature of Metal-Carbon bond ; Grignard reagent : Preparation (using haloalkane and haloarene) ; Reaction of Grignard reagent with water, aldehydes and ketones ( preparation of primary, secondary and tertiary alcohols), carbon dioxide, HCN, RCN, ester and acid chloride

Applied Chemistry :    13 teaching hours.

Unit 18. Chemistry in the Service of Mankind  : 4 hrs

Polymers : Addition and condensation polymers ; Elastomers and fibres ; Natural and synthetic polymers ; Some synthetic polymers (polythene, PVC, Teflon, polystyrene, nylon and bakelite ; Dyes : Introduction; Types of dyes on the basis of structure and method of application; Drugs :Characteristics of drugs; Natural and synthetic drugs ; Classification of some common drugs; Habit forming drugs and drug addiction ; Pesticides : Introduction to insecticides, herbicides and fungicides

Unit 19. Cement    : 4 hrs

Introduction ; Raw materials for cement production ; Main steps in cement production (crushing and grinding, strong heating and final grinding) ; Types of cement- OPC and PPC ; Portland cement process with flow-sheet diagram ; Cement Industry in Nepal.

Unit 20. Paper and Pulp    :  3 hrs

Introduction ; Raw materials ; Sources of raw materials; Stages in production of paper; Flow-sheet diagram for paper production ; Quality of paper.

Unit 21. Nuclear Chemistry and Applications of Radioactivity : 2 hrs

Natural and artificial radioactivity ; Units of radioactivity; Nuclear reactions ; Nuclear fission and fusion reactions ; Nuclear power and nuclear weapons ; Industrial uses of radioactivity ; Medical uses of radioactivity ; Radiocarbon dating ; Harmful effects of nuclear radiations .

The post NEB New Syllabus (Curriculum) of Class 11 and 12 Chemistry : 2077 appeared first on Online Chemistry notes.

Allotropes of phosphorus :

Phosphorus exists on following allotropic forms :

1. White or yellow phosphorus
2. Red phosphorus
3. Black phosphorus
4. Violet phosphorus
5. Scarlet phosphorus

Among them white and red phosphorus are more common.

        1. White Phosphorus :

      Chemical properties of (white) phosphorus:

• Action with air (O₂) : Phosphorescence : Phosphorus is highly reactive and it burns(oxidize) in air giving yellow-green flame forming phosphorus pentoxide and trioxide. This phenomenon is called phosphorescence.

Q) why is phosphorus stored in water?

→ Phosphorus is highly reactive and it easily oxidized in the presence of oxygen at room temperature and burns with yellow- green flame. This phenomenon is called phosphorescence. Due to this reason phosphorus is stored in water.

• Action with chlorine : Phosphorus forms trichloride and pentachloride with chlorine

Note: similar reaction for bromine and iodine too.

• Action with metal : phosphorus combines with metals like Na, K, Mg, Ca, etc to form metal phosphide.

• Reducing property : Phosphorus is reducing agent. It reduces conc. HNO₃ to NO₂ and conc. H₂SO₄ to SO₂.

• Action with caustic alkali (i.e. Caustic soda or caustic potash) :

When phosphorus is boiled with aqueous solution of caustic soda(NaOH) or caustic potash(KOH), phosphine gas is formed.

Structure of white phosphorus :

    2. Red Phosphorus :

When white phosphorus is heated at about 250⁰C in an inert atmosphere( of nitrogen or carbondioxide or coal gas) for several hours then it is converted into red phosphorus.

Structure of red phosphorus:

Uses of phosphorus :

• It is to prepare poison for killing rats.
• It is used in match industries.
• It is used in manufacture of phosphate fertilizer.
• It is used to prepare phosphine gas, phosphoric acid, etc.

Phosphorus hydride (Phosphine) (PH₃) :

Laboratory Preparation of phosphine :

Phosphine gas is prepared in laboratory by heating white phosphorus with caustic soda or caustic potash in an inert atmosphere.

During the preparation of phosphine, some quantity of diphosphine(P₂H₄) is formed. Due to presence of highly inflammable diphosphine, PH₃ gas burns with air as it comes out of water and forms vertex rings of phosphorus pentoxide.

Hence, during the preparation of phosphine gas all air inside the reaction flask is replaced by inert gas like CO₂ to minimize the risk of explosion. The phosphine gas evolved should be first passed through freezing mixture where diphosphine is condenced but phosphine is not condensed. Then the pure phosphine gas is collected in a gas jar by downward displacement of water.

Chemical Properties of Phosphine :

• Decomposition : Phosphine gas dissociates at 4400C to give red phosphorus and hydrogen.

• Combustion ( action of air) : Phosphine is non-supporter of combustion. But when phosphine is heated with air phosphorus pentoxide or phosphoric acid is formed.

• Reducing properties :
• Reduction of AgNO₃ solution : When PH3 gas is passed through AgNO3 solution then metallic silver along with phosphorus acid and nitric acid is formed.

Q) What happens when the gas produced by the action of white phosphorus with sodium hydroxide is passed through silver nitrate solution?

• With CuSO₄ solution : Phosphine gives black ppt. of copper phosphide with CuSO₄ solution. This is test reaction of phosphine.

Uses of phosphine :

• It is used to the formation of smoke screen during wars.
• It can be used as reducing agent.

Structure of Phosphine gas :

Oxides of phosphorus:

Phosphorus trioxide (P₂O₃) :

Uses : It is used to prepare Phosphorous acid and Phosphoric acid.

Structure of P₂O₃ : It exists in dimer form i.e. P₄O₆.

Phosphorus Pentoxide (P₂O₅) :

Uses :

• It is used as dehydrating agent in organic reactions.
• It is used for preparing phosphoric acid.

Structure of P₂O₅ :

Oxyacids of phosphorus :

Orthophosphoric acid (H₃PO₄) :

Preparation :

In laboratory, phosphoric acid is prepared by heating red phosphorus with concentrated HNO3 in presence of iodine as catalyst.

       P₄ + conc. 20 HNO₃      →    4H₃PO₄ + 4H₂O + 20 NO₂

Chemical Properties :

• Action of heat :   When orthophosphoric acid is heated, it produces pyrophosphoric acid at 250⁰-260⁰C and metaphosphoric acid at 300⁰C with removal of water molecule.

• Acidic nature :It is tribasic( triprotic )acid. It ionizes in three steps and forms three series of salts with alkali.

Uses of phosphoric acid :

• It is used in the manufacture of phosphate fertilizers.
• It is used as rust removal agent, household cleaning agent, sanitizing agent, etc.

Structure of orthophosphoric acid and phosphate ion :

                           BORON :

Occurance : it is not found in free state in nature. It is found in combined states as boric acid, borax, etc.

Uses of boron :

• It is used in the steel industry for increasing hardness of steel.
• Small amount of boron compound is essential for plant growth.
• It is used as semiconductor for making electronic devices.

Boric acid (Ortho boric acid) :

Molecular formula : H₃BO₃ or B(OH)₃

Uses :

• It is used as an antiseptic. Its aqueous solution is used in washing eyes, nose, ear,etc.
• It is used as a preservative for milk and food stuffs.

Borax :

Molecular formula : Na₂B₄O₇. 10H₂O

Uses :

• It is used to detect basic radicals in salt analysis (borax bead test).
• is used as a preservative for food stuffs.
• It is used in manufacture of soaps, washing powder, etc.

                                  SILICON :

Uses of silicon :

• It is used to make chips used in electric devices.
• It is used to make carborundum which is used as an abrasive.
• Silica (SiO2) is used as building material in making cement.

Carborunbum : Silicon carbide (SiC).

Use : It is used as abrasive.

Silica : SiO₂

Uses :

• Used as building material in making cement.
• Used for preparing glass.
• Used for making silica gel which is used for absorbing moisture.

Silica gel : i.e hydrated silica : SiO₂. xH₂O

Use : It is used for absorbing moisture and as an adsorbent in chromatography.

Sodium silicate : Na₂SiO₃

Uses :

• It is used for making glass.
• It is used for making silica gel.

                         Noble Gases

The elements which are present in zero group or 18 group of Modern periodic table are known as noble gases. Helium, neon, argon, krypton, xenon and radon constitute the noble gas family. They are very less reactive at normal temperature and pressure.

Uses of noble gases :

• Helium is used for filling ballons.
• Argon is used in electric bulb.
• Radon is used for the treatment of cancer i.e. in radiography.

Q. what are noble gases? Why are they chemically inert?

→ The elements which are present in zero group or 18 group of Modern periodic table are known as noble gases. They are chemically inert because of stable valence shell with octet electrons except in helium( duplet).

Eg. He : 1s² Ne : 1s²2s²2p⁶

They have high ionization energy so transfer and share of electrons is very difficult. Hence, noble gases are chemically inert.

Q) The first ionization energy of noble gases is higher than that of halogens, explain.

→ The electronic configuration of noble gases is very stable due to presence of fulfilled electrons in the outermost orbital. So, very high amount of energy is required to remove electrons from the outermost orbital and the value of ionization energy is very high. But in case of holegens, there are seven electrons in outermost orbital, i.e. not fulfilled . Hence, I.E. of noble gases is higher than that of halogens.

          Environmental Pollution :

Air Pollution : The contamination of air with harmful gases, dust, smoke , etc. is known as air. The pollutants like CO, NO, NO₂, SO₂, O₃, smoke, dust, etc. which pollute the air are called air pollutants.

Smog : It is the combination of smoke and fog.

• Chemical smog : Sulphur dioxide (SO₂) and particular matter present in air form this type of smog during cold and humid climate. When SO₂ combines with water vapour, it forms sulphurous acid which condenses on smoke, dust particles etc. and form a mixture called chemical smog.

→ It causes respiratory problems such as bronchitis, pneumonia, etc.

• Photochemical smog : The smog which is formed by the reaction of automobile exhaust in the presence of sunlight is called photochemical smog.

The major components of photochemical smog are NO, CO, NO₂, hydrocarbons, etc.

→ The photochemical smog causes headache, eye problem, skin problem, etc.

→ it reduces visibility and affects the air and road traffic.

Acid Rain :

Generally rain water is slightly acidic having pH about 5.6 due to dissolved CO₂ in water. However, pH of the rain water is decreased below pH 5.6 if the acidic oxides like oxides of sulphur and nitrogen get dissolved in it. Such rain water is called acid rain.

→ It can destroy the life of aquatic animals.

→ It causes damage of buildings and rocks.

→ It increases the acidity of soil and decreases the fertility of soil.

Green house effect :

The green house effect is a natural process that warms the earth. When the energy from sun reaches the earth’s atmosphere, some of it is reflected back to space and the rest is absorbed by greenhouse gases.

Greenhouse gases include water vapour, carbondioxide, methane, nitrous oxide, ozone and some artificial chemicals such as chlorofluorocarbon (CFCs).

The absorbed energy warms the atmosphere and the surface of the earth. This process maintains the temperature of our earth due to which the life is possible in earth.

The post A brief note on Phosphorus, Boron, Silicon, Noble gases and Environmental Pollution for class 11. appeared first on Online Chemistry notes.

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INORGANIC CHEMISTRY :

SET I :

Generally one long question(10 marks) and one short question( 5 marks) and few very short questions (2 marks) are asked from this portion along with their reactions which are listed in Q.no. 22, 23 and 25 of short questions mentioned below. Sample questions:

Q 1) Write the principle and self-explanatory diagram for the manufacture of suphuric acid from pyrite ore by contact process. How would you show that sulphuric acid acts as:

a) an acid b) a dehydrating agent

Write down the test reaction of sulphate ion in its aqueous solution. – – – – [6 + 2 + 2 ]

• First of all read question carefully , understand it and then write answer. This question requires principle and well labeled diagram only ( i.e. procedure/process is not needed).
• In second portion of the question only 2 marks is given for (a) and (b) so write only one or two reactions to show each.

Q 2 ) Write balanced chemical equation for the preparation of ammonia by Haber’s process. How does ammonia reacts with :

a. sodium b. chlorine c. CuSO₄ – – – – – [5]

• This question requires balanced chemical reaction only ( not more language of principle and procedure.]

SET II

Usually one short question (5 marks) and few very short questions are asked from this portion. Sometimes long question(10 mark) is also asked from (ii) and (iii) along with reactions mentioned below in Q. no. 24 and 25 of short questions. Sample questions :

Q1) Write the chemical reaction for the laboratory preparation of H₂S gas. How does Kipp’s apparatus work to supply H₂S gas in salt analysis? – – – – [5]

• First portion requires only a chemical reaction of lab preparation ( not principle, figure and procedure).
• Second portion requires the explanation on intermittent supply of H₂S gas by Kipp’s apparatus with figure.

Q 2) How is pure sulphur dioxide prepared in the laboratory? How does sulphur dioxide react with : a. acidified KMnO4 b. HI c. Potassium iodate.

How is bleaching action of SO₂ differs from Cl₂ ? – – – – – [5+3+2]

• First portion requires all principle, figure and procedure for lab preparation.
• Last portion requires table containing diffences between bleaching action of SO₂ and Cl₂ .

Q 3) Give the laboratory method of preparation of carbon monoxide. Why is carbon monoxide extremely poisonous. – – – – [4+1]

Q 4) Give a balanced chemical reaction for the preparation of CO in the laboratory. Why is CO harmful gas. – – – – [1+1]

• This question seems similar to the above question but it is very short question. First portion of this question requires reaction only for lab preparation of CO.

Some important short questions from Inorganic chemistry (Non – metals) :

1. What is nascent hydrogen? Mention an example to show nascent hydrogen is more powerful reducing agent than molecular hydrogen.

2. Name the isotopes of hydrogen. Which isotope is least abundant/radioactive ?

3. Differentiate between ortho and para hydrogen.

4. Mention an important use of:

• Deuterated water(heavy water)
• Tritium
• Ozone
• Nascent hydrogen
• Deuterium.

5.  Write two examples of each:

• Amphoteric oxide
• Neutral oxide
• Peroxide.
• Mixed oxide.

6. How does formation of ozone takes place in stratosphere? What is meant by tailing of mercury?

7. Why is water an excellent solvent for polar substances?

8. Explain why :

• Ammonia can not be dried by passing through conc. H₂SO₄.
• conc. HNO₃ is stored in dark bottle?
• Phosphorus is stored in water.
• Conc. H₂SO₄ is diluted by adding acid into water but not water into acid?
• H₂SO₄ always acts as an oxidizing agent but not reducing agent.

9. What is the laboratory test of:

• nitrate ion (ie. Nitric acid) (i.e. ring test)
• Cl ^–, Br ^– and I ^–
• Sulphate ion(sulphuric acid)

10. What is aqua regia? Write it’s reaction with gold.

11. Compare the bleaching properties of Cl₂ and SO₂

12. Give a chemical reaction for the preparation of HCl. Why HBr and HI can not be prepared by treating conc. H₂SO₄ with bromide and iodide?

13. How does bromine/chlorine reacts with hot and conc. NaOH?

14. Why is CO extremely poisonous?

15. What is meant by allotropy? Which one is hardest allotrope and latest discovered allotrope of carbon? Write one use of each.

16. What happens when white phosphorus is heated with aqueous caustic soda? ( i.e. preparation of phosphine).

17.Write molecular formula and one use of:

• Borax            • Hypo
• Boric acid     • Carborundum
• Silica gel

18. Why are noble gases chemically inert? Write two uses of noble gases.

19. What are the major pollutants for photochemical smog? Write its major effects.

20. How do oxides of sulphur(SO₂) and nitrogen responsible for acid rain? Write major effects of acid rain.

21. What is green house effect? How does CFS deplete ozone layer.

22. Reaction of ammonia with:-

• CO₂ gas         • Cl₂ gas
• CuSO₄ solⁿ    • Na-metal      • CuO
• Mercurous nitrate/chloride paper.

23. Reaction of nitric acid with:-

• Zn     • Mg    • Cu
• Fe      • I₂       • P₄

24. Reaction of CO with :

• Ni        • Cl₂         • NaOH
• Water gas (CO+H₂) is heated over ZnO+Cu.

25. Reaction to show that:

• H₂SO₄ as :- (a)an acid (b) an oxidizing agent (c) dehydrating agent
• SO₂ as an oxidizing agent
• H₂S as : (a) a reducing agent (b) an analytical reagent.
  

  ---

SET III :

This set is from metals. Usually one long question (10 marks) is asked from (1) and (2) numbers along with their reactions mentioned below in no. 8,9,10 and 11 of short questions.

Sample question:

Q1) Explain the Caster-Kellner process for the manufacture of caustic soda. Why do alkali metals impart characteristic colour to flame? How does NaOH reacts with a) CO₂ b) Zn – – – – – – [ 6 + 2 + 2 ]

One short question( 5 mark) is asked from (3).

Sample question :

Q2 ) Give the chemistry of plaster of paris. – – – – – – [5]

• Write chemistry means write some preparation methods, properties (physical+ chemical) and uses.

Some important short questions from metals :

1. ‘Every ore is a mineral but every mineral is not ore’, give reason.

2. Wrire differences with example between :

• Calcination and Roasting.
• Pyrometallurgy and electrometallurgy.
• Flux and Slag.

3. Write short note on:

• Froth floatation process.
• Carbon reduction process
• Aluminothermite process.

4. Explain why:

• Carbon reduction process not applied for the extraction of alkali metal.
• Alkali metals impart characteristic colour to the flame.
• Sodium metal gets turnished in air.
• Quick lime produces hissing sound when added into cold water.
• Sodium metal is kept in kerosene.
• Sodium fire at laboratory not extinguished by adding water.

5. Define the terms:

• Dead burnt plaster.
• Setting of plaster of paris.

6. Write important characteristics of alkali metals and alkaline earth metals.

7. Write molecular formula and one use of : washing soda, backing soda, caustic soda and soda ash.

8. Convert:

• Caustic soda to washing soda and baking soda.
• Sodium into washing soda.
• Sodium into sodium silicate.
• Washing soda into soda ash.

9. Action of sodium(Na) with :

• Water       • NH₃
• Moist air

10. Action of caustic soda(NaOH) with :

• Phosphorus      • CO₂
• Sulphur             • Zinc
• Ammonium chloride

11. Action of washing soda(Na₂CO₃) with :

• Air             • Heated sand(SiO₂)
• Heat          • CaCl₂

ORGANIC CHEMISTRY :

SET IV :

One Short question (5 Marks ) is asked out of two lab preparations mentioned in no.1 . Sample questions :

Q1) How is ethene prepared in the laboratory ? What happens when ethene is passed through Baeyer’s reagent ? – – – – – – – [4 + 1 ]

One short question ( 5 marks) is asked from no. 2, 3,4 and 5 . Usually one question is asked from lassaignes test for nitrogen and Homologous series. Sample questions :

Q2) Define homologous series. What are the characteristic features of homologous series. Write structural formula and IUPAC name of first member of ketone series. – – – – [1+3+1]

Q3) Write short note on Lassaigne’s test for nitrogen. – – – – – – [5]

Q4) Write short note on :

a. Markovnikov’s rule. b. Ozonolysis. – – – – – – – [5]

Some important short questions from Organic chemistry :

1. Explain why :

• Sodium extract( Lassaigne’s extract) is alkaline in nature.
• Sodium extract is boiled with conc. nitric acid while testing for halogens.

2. Give the functional isomers of : a) C₃H₈O b) C₃H₆O and c) C₃H₆O₂ and write their IUPAC name.

3. What are electrophiles and nucleophiles? Write two examples of each.

4. Define inductive effect and give it’s important application.

5. Define antiknocking agent( Gasoline additive) and write one example .

6. What is the function of TEL in gasoline?

7. Define octane number. A fuel has octane number 80. What does it mean?

8.What is cracking of petroleum?

9. What happens when :

• Bromoethane is heated with sodium metal in presence of dry ether.
• Sodium acetate( sodium ethanoate) is hated with soda-lime.
• 2- bromopropane is heated with alc. KOH.
• Ethene(ethylene) is passed through Baeyer’s reagent( Alkaline solution of KMnO₄).
• Ethyne(acetylene) gas is passed through ammonical solution of silver nitrate.

10. Write one example of each:

• Kolbe’s reaction
• Dehydrohalogenation reaction
• Decarboxylation reaction

11. Write a chemical test to distinguish:

• Ethyne(alkyne) from ethene(alkene).
• Ethene/ethyne from ethane.

PHYSICAL CHEMISTRY :

SET V :

This set is from physical chemistry. Usually one long question (10 marks) and one or two short question (5 marks) and some very short questions are asked from this portion along with numerical problems. Sample questions :

Q 1 ) State and explain the Graham’s law of diffusion of gas. Give its an application. 0.23 g of a volatile liquid occupies 126.4 cc at 27⁰C and 760 mmHg pressure. Calculate the molecular weight of the liquid. How many molecules of the liquid are present in 0.23 gm ? – – [5+1+4]

Q 2 ) State Avogadro’s Law. Using the law. Apply the law to deduce relationship between molecular mass and vapour density. – – – – – – – [5]

Q 3 ) 17 gm of ammonia is is completely reacted with 45 gm of oxygen to produce NO and H₂O.

• Which is limiting reagent? — – – – — [5]
• Calculate the number of moles of unreacted reactant left over.
• What volume of NO is produced at NTP ?
• Calculate the mass of water produced.

SET VI :

This set is also from physical chemistry. Usually two short (5 marks) and few very short (2 marks) questions are asked from no. 1 – 8 of this set. Sample questions :

Q 1 ) Write short note on Le- Chatelier’s principle . – – – [5]

Q 2 ) Write down the essential postulates of Bohr’s atomic model. How did it overcome the limitations of Rutherford’s atomic model ? – – – [5]

Q 3 ) Give values of all four quantum number of 11^th electron of Magnesium (atomic no. 12). – – [2]

One short question is asked from no. 9 of this set. Sample question :

Q 4 ) Distinguish between oxidant and reductant. Balance the following reaction by oxidation number or ion electron method : MnO₄ ^– + H₂O₂ = MnO₂ + O₂ + OH ^– – – – – [5]

Some important short questions from Physical chemistry :

1. What is ideal gas? Under what conditions will a gas nearly behaves like an Ideal gas?

2. Why Hund’s rule is called rule of maximum multiplicity?

3. Define the terms : a. Surface tension b. viscosity. c. aqueous tension.

4. Give proper reason for the following:

• Rain (liquid) drops are spherical.
• Alcohol can flow easily but honey can not.
• Evaporation takes place from the surface of liquid.
• It is more efficient to wash clothes is hot water than cold water.

5. What is evaporation? How does it differs from boiling?

6. Distinguish between:

• Isotropic and anisotropic substances giving an example of each.
• Crystalline and amorphous solid.
• Crystal lattice and unit cell.

7. Mention one important character and an example of each:

• Efflorescence (efflorescent substance)
• Deliquescence ( deliquescent subastance)
• Hygroscopy (hygroscopic substance)

8. Why electron does not jump into the nucleus.

9. Define (a)nuclear fusion (b) nuclear fission (c) thermonuclear reaction, giving one example of each.

10. Distinguish between:

• Nuclear reactions and chemical reactions.
• Controlled nuclear fission and uncontrolled nuclear fission.

11. What is hydrogen bond? Differentiate between intramolecular and intermolecular H- bonding with example.

12. Define dipole moment and give it’s two important applications.

13. Write down the Lewis structure of :

• (NH₄)₂SO₄        • H₂SO₄ , etc .

14. Differentiate between polar and non polar covalent bonds with one example of each.

15. State modern periodic law. On what basis does Mendeleev’s periodic law differs from modern periodic law.

16. What is periodicity and its causes? How do atomic radii( size) vary in a group and a period?

17. State and explain the law of equivalent proportion/ reciprocal proportion/ multiple proportion.

18. Define the terms:

• Oxidation • Oxidation number(state)
• Reduction • Oxidant/reductant.

19. What is redox reaction? Show that oxidation and reduction takes place simultaneously.

20. Calculate the weight of 11.2 liters of CO₂ gas at STP.

21. Define equilibrium constant (Kc). Write the relation between Kp and Kc for the following reaction:

22. How do increase in temperature and pressure affect the equilibrium of the following reaction:

See class 11 chemistry notes ⇒

The post Class 11 Chemistry : Important Questions, Topics and Ideas for NEB exam. appeared first on Online Chemistry notes.

Manufacture of ammonia by Haber’s process:

When a mixture of nitrogen and hydrogen gas in the ratio 1:3 by volume is heated at a temperature of 450-500⁰C and 200-900 atmospheric pressure in the presence of iron as catalyst and molybdenum as promoter, ammonia gas is produced.

Conditions for optimum yield of ammonia : The reaction is exothermic, reversible and occurs with a decrease in volume. So, Le- Chatelier’s principle can be applied here to get higher yield.

1. Low temperature : Since the reaction is exothermic, low temperature is favourable for the formation of ammonia. If the temperature is below 450⁰C, N₂ and H₂ react too slowly to attain equilibrium state. Thus an optimum temperature of about 450-500⁰C is maintained.
2. High pressure : The total volume of product is lower than total volume of reactant so, equilibrium shifts in forward direction with the increase in pressure. In practice, 200 to 900 atmospheric pressure is applied.
3. High concentration of reactants : Since reaction proceeds in forward direction with decrease in volume, so either one or both reactants( H₂ and N₂) should be used in excess amount for high yield of NH₃.
4. Catalyst : Presence of the catalyst speeds up the rate of reaction. Finely divided Iron catalyst and Molybdenum promoter is used.
5. Purity of hydrogen and nitrogen : The nitrogen and hydrogen gas should be very pure, otherwise the catalyst is poisoned and decreases catalytic activity.

Procedure : Nitrogen and hydrogen gas in the ratio 1 : 3 by volume is mixed by passing through the compressor where 200 to 900 atm pressure is maintained Then this mixture is passed in a catalyst chamber containing finely divided iron with little amount of molybdenum. The chamber is heated electrically to about 450-500⁰C to initiate the reaction. Under these conditions of temperature and pressure, only about 15% reactant gases are converted into ammonia. The gas obtained from the catalyst chamber contains ammonia along with unreacted hydrogen and nitrogen. The gases mixture is then passed through a condenser where ammonia gets condensed and collected in a receiver while unreacted H₂ and N₂ gas is recirculated by recirculation pump and reprocessed to get more ammonia.

Physical Properties of Ammonia :

1. It is a colourless and pungent smelling gas.
2. It is lighter than air.
3. It is easily liquefiable gas. It can also be solidified. Melting point of solid ammonia is -78⁰C and boiling point of liquid ammonia is -33.4⁰C.
4. It is neither combustible nor a supporter of combustion.
5. It is highly soluble in water as it forms intermolecular hydrogen bond with water.

Chemical Properties (reactions) of Ammonia :

1. Basic nature:

• Ammonia changes the colour of moist litmus paper into blue.
• It dissolves in water to give OH^– ions.
• It reacts with acid to give salt.

• Due to presence of lone pair of electrons on the nitrogen atom, ammonia acts as a Lewis base,

     2. Reducing property : It acts as reducing agent.

• Action with oxygen : When ammonia is heated with oxygen, it gets oxidized to nitrogen gas. Here ammonia acts as reducing agent.

But when a mixture of NH₃ and O₂ is heated at about 850⁰C in presence of platinum then nitric oxide is formed.

•  Action with metal oxides : when ammonia gas is passed over heated copper oxide or lead oxide, metal oxide is reduced to respective metals.

•  Action with bleaching powder : When ammonia gas is heated with bleaching powder, it reduces CaOCl₂ into CaCl₂.

   3.   Action with metals: a. When ammonia reacts with molten sodium or potassium gives amide and hydrogen.

     b) Lithium and magnesium give nitride instead of amide with ammonia.           

4.   Dissociation (decomposition) of ammonia : When electric spark(current) is passed through ammonia or when ammonia is passed through a red hot tube at about 500⁰C then ammonia decomposes to nitrogen and hydrogen.

5. Action with halogens : Depending upon the amount of halogen and ammonia and reaction conditions, ammonia gives different products.

• Action with fluorine :

• Action with chlorine :

• Action with bromine :

• Action with iodine :

    6. Action with carbon dioxide (CO₂) : Ammonia reacts with carbon dioxide at 130-150⁰C under pressure 220 atm to give urea.

     7. Precipitation reaction : Ammonia gas dissolves in water to form  ammonium hydroxide.

When ammonium hydroxide solution is added into some salt solution  such as FeCl₃, AlCl₃, CrCl₃, ZnCl₂,etc. then ppt. of corresponding hydroxides are formed.

• Action with copper sulphate solution :

When ammonia gas is passed into copper sulphate solution, at first a bluish white precipitate of Cu(OH)₂ is formed which dissolves in exces of ammonia forming a deep blue coloured tetrammine copper(II) sulphate.

    8. Action with mercurous nitrate paper : When mercurous nitrate  paper is placed over a jar containing ammonia gas then paper changes into black. This is due to the formation of mercuric amino nitrate.

    9. Action with mercuric chloride : Mercuric chloride reacts with ammonia to give white ppt of mercuric amino chloride.

    10. Reaction with Nessler’s reagent : Alkaline solution of potassium mercuric iodide (K₂HgI₄) is called Nessler’s reagent. When ammonia gas is passed to Nessler’s reagent, a brown ppt. of Millon’s base is formed.

Uses of ammonia :

1. It is used for the manufacture of urea.
2. It is used as cooling agent in refrigerator.
3. It is used for reducing metal oxide.
4. It is used to manufacture nitric acid by Ostwald’s process

Structure of ammonia :

REFERENCES :

• Agrawal, S. K., Lal, K., Advanced Inorganic Chemistry, Fifth Revised Edition, Pragati Prakashan, Meerut, 2001.
• Cotton, F. A., and Wilkinson, G., Advanced Inorganic Chemistry, Fifth edition, John Wily and Sons, Singapore, 1995.
• Day, C.M., Selbin, J., Theoritical inorganic Chemistry, second edition, Affiliated East-West Press Pvt. Ltd., New Delhi, 2002.
• Lee, j. D., Concise Inorganic Chemistry, Fifth Edition, Joh, Wiley and Sons, Inc., 2007.
• Sarkar, R., General and Inorganic Chemistry, Second Edition, New Central Book Agency(P) Ltd., India, 2007.
• Shriver, D. F., Atkins, P. W., Inorganic Chemistry, Fifth Edition, Oxford university Press, 2010.
• Mitra, L.A. , A Text Book of Inorganic Chemistry, Ghos and Company, 61^st edition, 1996.
• https://www.aiche.org/resources/publications/cep/2016/september/introduction-ammonia-production
• https://pubchem.ncbi.nlm.nih.gov/compound/Ammonia
• https://en.wikipedia.org/wiki/Ammonia

The post Ammonia : Manufacture by Haber’s Process, Properties, Uses And Structure. appeared first on Online Chemistry notes.