Students of ICSE Class 10 should refer to Study of Compounds Ammonia and Nitric Acid ICSE Class 10 Chemistry board year questions and solutions. below which have come in past board exams. You should always go through questions that have come in previous years. This will help you to understand the pattern of questions in ICSE Class 10 Chemistry and prepare accordingly. This will help you to get better marks in ICSE Class 10 Board Exams
ICSE Class 10 Chemistry Study of Compounds Ammonia and Nitric Acid Board Exam Questions
Students should learn the important questions and answers given below for Chapter Study of Compounds Ammonia and Nitric Acid in Chemistry for ICSE Class 10. These board questions are expected to come in the upcoming exams. Students of ICSE Class 10th should go through the below board exams questions and answers which will help them to get more marks in exams.
Board Exam Questions Study of Compounds Ammonia and Nitric Acid ICSE Class 10 Chemistry
(a) Most of the nitric acid today is manufactured by Ostwald’s process. In this process a mixture of pure dry ammonia and air in the ratio of (1) ………by volume is first compressed and then passed over (2) ………at about (3) ………°C. This results in the oxidation of ammonia into (4) ……… which combines with (5) ………of the air to give (6) ……… . This is an acidic gas from which nitric acid can be obtained by simply dissolving in (7) ……… .
Answer
(1) 10 : 1
(2) platinum gauze
(3) 800
(4) nitric oxide
(5) oxygen
(6) nitrogen dioxide
(7) water
(b) Nitrogen and hydrogen combine in the presence of a catalyst to give (1)______ gas. When the above mentioned gas is passed through water it forms a solution which will be (2) _______ in nature and the solution contains (3)________ ions and (4) ________ ions. The above solution when added to iron (II) sulphate solution, gives a (5) ________ coloured precipitate of iron (II) hydroxide.
Answer
(1) ammonia
(2) alkaline
(3) ammonium
(4) hydroxyl
(5) dirty green.
(c) Question. Ammonia in liquid form is ……………
Answer
neutral
Question. Ammonia gas is collected by ………
Answer
a downward displacement of air
Question. Nitric acid is also called as……………
Answer
aqua fortis
Question. The alkaline behaviour of liquor ammonia is due to the presence of …………
Answer
OH– ions
Question. ……………is used as a catalyst during preparation of ammonia.
Answer
Molybdenum
Question. Liquor ammonia fortis is a saturated solution of ……………
Answer
NH4OH
Question. ……………turns turmeric paper brown.
Answer
Ammonia
Question. The salt solution which gives white ppt. on the addition of ammonium hydroxide solution is ……………
Answer
magnesium chloride
Question. Excess of ammonia reduces chlorine to ………………
Answer
NH4Cl
Question. The gas most difficult to liquefy is………………
Answer
hydrogen
Question. When ammonium chloride is heated, it undergoes ……………….. .
Answer
thermal dissociation
Question. Heating ammonium chloride with sodium hydroxide produces ……………….. .
Answer
ammonia
Question. Heating a solution of ammonium chloride and sodium nitrite produces ……………….. .
Answer
nitrogen
Question. Cold, dilute nitric acid reacts with copper to form…………
Answer
nitric oxide
Question. The reaction of …………with dil. nitric acid is an example of neutralisation reaction.
Answer
CaO
Question. Lead nitrate is a…………salt of nitric acid.
Answer
normal
Question. The mineral acid obtained from conc. nitric acid on reaction with a non-metal is………
Answer
H2SO4
Question. A nitrate which leaves a black residue on heating is…………
Answer
Cu(NO3)2
Question. The nitrate which on heating melts and liberates only one neutral gas is …………
Answer
NaNO3
Question. The oxidised product obtained on reaction with H2S gas and dil. HNO3 is …………
Answer
sulphur
Question. Ammonium nitrate is used in preparing ………………
Answer
explosives
Question. Nitric acid is manufactured by ……………… process.
Answer
Ostwald’s
Multiple Choice Questions
Question. Ammonia can be obtained by adding water to :
(a) Ammonium chloride
(b) Ammonium nitrite
(c) Magnesium nitride
(d) Magnesium nitrate
Answer
C
Question. Ammonia is soluble in water because :
(a) A polar molecule
(b) An acid
(c) A base
(d) A simple covalent compound
Answer
A
Question. Nitrogen gas can be obtained by heating :
(a) Ammonium nitrate
(b) Ammonium nitrite
(c) Magnesium nitride
(d) Ammonium chloride
Answer
B
Question. The nitrate which evolves laughing gas on decomposition :
(a) Ferric nitrate
(b) Calcium nitrate
(c) Sodium nitrate
(d) Ammonium nitrate
Answer
D
Question. Rotten egg smell is due to the liberation of :
(a) HCl gas
(b) Cl2 gas
(c) H2S gas
(d) SO2 gas
Answer
C
Question. The temperature at which catalytic oxidation of ammonia is carried out :
(a) 200°C
(b) 800°C
(c) 1000°C
(d) 500°C
Answer
B
Question. With excess of chlorine, NH3 forms :
(a) NH4Cl
(b) NCl3
(c) NOCl
(d) N2Cl
Answer
B
Question. Liquid NH3 is employed in refrigerator, because :
(a) It is more basic
(b) It is stable hydride
(c) It has a high dipole moment
(d) It has high heat of evaporation
Answer
D
Question. Ammonia nitrate is used in :
(a) Lining vessels
(b) Paints
(c) Textile industry
(d) Preparing explosives
Answer
D
Question. The brown ring test is used for the detection of :
(a) CO2 –3
(b) NO–3
(c) SO2 –3
(d) Cl–
Answer
B
Question. The composition of brown ring formed at the junction is :
(a) FeSO4.OH
(b) FeSO4.NO
(c) FeSO4.H2O
(d) FeSO4
Answer
B
Question. Which acid is prepared by Ostwald’s process :
(a) Nitric acid
(b) Oleic acid
(c) Sulphuric acid
(d) Tartaric acid
Answer
A
Give One Word/Chemical Term
Question. An element that acts as a promoter in the industrial preparation of ammonia.
Answer
Molybdenum
Question. A compound used to dry ammonia.
Answer
Quick lime (CaO)
Question. A catalyst used during Haber’s process.
Answer
Finely divided iron
Question. Products obtained by the catalytic oxidation of ammonia.
Answer
Nitric oxide and water vapour
Question. Ammonium salt used in the preparation of alum.
Answer
Ammonium sulphate
Question. A fertilizer that reacts slowly with moisture to give ammonia.
Answer
Nitrolium (CaCN2)
Question. A fertilizer made by combining ammonia and carbon dioxide.
Answer
Urea (NH2CONH2)
Question. The product of oxidation of ammonia in Ostwald process.
Answer
Nitrogen (II) oxide (nitric oxide) and steam
Question. A compound which is manufactured by the oxidation of ammonia.
Answer
Nitric acid
Question. Experiment which demonstrates the extreme solubility of ammonia.
Answer
Fountain experiment
Question. The fertilizer formed when nitrogen is reacted with calcium carbide at high temperature.
Answer
Nitrogen
Question. A white ppt. formed when an aqueous solution of the compound is added to a solution of barium chloride
Answer
Ammonium sulphate
Question. A colourless gas which becomes reddish brown when it comes in contact with atmosphere.
Answer
Nitric oxide
Question. The common name of carbamide.
Answer
Urea
Question. An explosive formed when ammonia and chlorine react together.
Answer
NCl3
Question. The compound known by the name, Aqua fortis.
Answer
Nitric acid
Question. A catalyst used in the manufacture of nitric acid by ostwald’s process.
Answer
Platinum
Question. The process by which nitric acid is obtained on a large scale.
Answer
Ostwald’s process
Question. Salt used in the laboratory to prepare nitric acid.
Answer
Sodium or potassium nitrate
Question. The compound that makes laboratory acid yellow.
Answer
Nitrogen dioxide (NO2)
Question. Organic liquid that bursts into flames when sprayed into highly conc. nitric acid.
Answer
Turpentine
Question. Gas obtained by treating copper with dilute nitric acid.
Answer
Nitric oxide
Question. Products obtained by heating concentrated nitric acid.
Answer
Water, nitrogen dioxide and oxygen
Question. Insoluble component present in super phosphate of lime.
Answer
Calcium sulphate
Question. The gas produced by the action of dil. HNO3 on copper.
Answer
Nitric oxide
Question. A compound formed when nitric acid and hydrochloric acid reacts together.
Answer
Nitrosyl Chloride
Question. The property of nitric acid which allows it to react with copper.
Answer
Oxidising agent
Question. A concentrated acid which oxidies sulphur directly to H2SO4.
Answer
Conc. HNO3
Question. The gas produced when copper reacts with conc. HNO3.
Answer
NO2
Question. A gas which possess the smell of rotten eggs.
Answer
H2S
Question. The test carried out with freshly prepared ferrous sulphate.
Answer
Brown ring test
Question. A nitrate which leaves behind no residue on heating.
Answer
Ammonium nitrate
Question. A solution which gives nitrogen dioxide with copper.
Answer
Conc. HNO3
Identification of Gases
Q. Name the gas evolved in the following cases :
Question. The gas produced when excess ammonia reacts with chlorine.
Answer
Nitrogen
Question. The gas produced when copper reacts with concentrated nitric acid.
Answer
Nitrogen dioxide
Question. The gas produced when magnesium reacts with dil. nitric acid.
Answer
Hydrogen
Question. The gas produced when ammonium nitrite undergoes a thermal decomposition.
Answer
Nitrogen
Question. The gas produced when dry ammonia and oxygen are ignited.
Answer
Nitrogen
Question. The gas evolved when dry ammonia and oxygen are passed over heated platinum and then allowed to cool.
Answer
Nitrogen dioxide
Question. The gas produced when ammonia gas is passed over heated litharge.
Answer
Nitrogen
Question. The gas produced when concentrated nitric acid is added to copper.
Answer
Nitrogen dioxide
Question. The gas produced when sodium nitrate is heated.
Answer
Oxygen
Question. The gas produced when ammonium nitrate is heated.
Answer
Nitrous oxide (Laughing gas N2O)
Question. The gas produced when sodium carbonate reacts with dilute nitric acid.
Answer
Carbon dioxide
Question. The gases produced when silver nitrate is heated.
Answer
Nitrogen dioxide and oxygen
Question. The gas produced when ammonia burns in an atmosphere of oxygen without any catalysts.
Answer
Nitrogen
Question. Calcium hydroxide and ammonium chloride.
Answer
Ammonia gas
Question. Sodium nitrite and ammonium chloride.
Answer
Nitrogen gas
State the Observation
1. A piece of moist red litmus paper is placed in a gas jar of ammonia.
Answer
A piece of moist red litmus paper turns blue when it is placed in a gas jar of ammonia.
This is because of the basic nature of ammonia gas.
2. Solution of ammonium chloride and sodium hydroxide are mixed and heated.
Answer
Ammonia gas is produced when ammonium chloride (NH4Cl) and sodium hydroxide (NaOH) is heated.
NH4Cl + NaOH ⎯→ NaCl + H2O + NH3 ↑
3. Ammonia is dissolved in water.
Answer
Ammonia dissolves in water to form a weak base, NH4OH.
4. When a glass rod dipped in hydrochloric acid is introduced into a gas jar full of ammonia, dense white fumes are produced.
Answer
Hydrochloric acid present on the glass rod reacts with ammonia to form dense white fumes of ammonium chloride.
NH3 + HCl ⎯→ NH4Cl
5. An aqueous solution of ammonia is added to a solution of ferric chloride.
Answer
When an aqueous solution of ammonia is added to ferric chloride solution, a reddish brown precipitate of ferric hydroxide is produced which is insoluble even in the excess of ammonium hydroxide.
FeCl3 + 3NH4OH ⎯→ Fe(OH)3↓ + 3NH4Cl
Ferric hydroxide
(Reddish brown ppt.)
6. Excess of ammonia is passed through an aqueous solution of lead nitrate.
Answer
A white coloured precipitate of lead hydroxide [Pb(OH)2] is formed which is insoluble in an excess of ammonia solution.
7. Ammonia is passed through excess chlorine.
Answer
When ammonia is passed through excess of chlorine, a highly explosive yellow liquid of nitrogen trichloride is obtained.
NH3 + 3Cl2 ⎯→ NCl3 + 3HCl
Nitrogen trichloride
(highly explosive)
(yellow liquid)
8. Ammonia is passed through black copper oxide.
Answer
When ammonia is passed through black copper oxide, it changes to red copper.
9. Ammonia is passed through yellow lead oxide.
Answer
When ammonia is passed through yellow lead oxide, it changes to silvery white lead.
10. Ammonia gas is burnt in an atmosphere of oxygen in the absence of catalyst.
Answer
A greenish yellow flame is observed when ammonia gas is burnt in an atmosphere of oxygen in the absence of catalyst
11. When a jar filled with ammonia gas is inverted in a trough filled with water.
Answer
Ammonia is highly soluble in water. When a jar of ammonia is inverted in a trough of water, a low pressure is created in a jar and the water rushes up, as the gas dissolves in water.
12. A fertilizer containing an ammonium salt gets spoiled, if accidentally mixed with slaked lime.
Answer
Slaked lime is a strong alkali, which reacts with ammonium salt present in fertilizer to liberate ammonia gas.
(NH4)2SO4 + Ca(OH)2 ⎯→ CaSO4 + 2NH3 + 2H2O
13. Copper turnings are heated with concentrated nitric acid.
Answer
When copper turnings are heated with concentrated nitric acid, copper nitrate, water and nitrogen dioxide gas (which has reddish brown colour and pungent smell) is evolved.
Cu + 4HNO3 ⎯⎯→ Cu(NO3)2 + 2H2O + 2NO2
14. Nitric acid reacts with glycerol.
Answer
Nitric acid react with glycerol in presence of conc. H2SO4 below 25°C to form glycerol trinitrate.
15. Nitric acid reacts with phenol in presence of conc. sulphuric acid.
Answer
Nitric acid reacts with phenol in presence of conc. sulphuric acid to form orange coloured compound, picric acid.
16. When a few drops of concentrated nitric acid are dropped on hot saw dust.
Answer
Hot saw dust catches fire. This is because concentrated nitric acid decomposes to give oxygen at a higher temperature.
4HNO3 ⎯→ 4NO2 + 2H2O + O2
Oxygen gas is a supporter of combustion and it supports the combustion of hot saw dust, which catches fire.
17. When a little water is added to a yellow coloured nitric acid.
Answer
The yellow colouration of nitric acid is due to the decomposition of nitric acid into nitrogen dioxide and other oxides of nitrogen. When a little water is added, all these oxides of nitrogen are dissolved and thus the acid becomes colourless
18. Concentrated nitric acid is added to copper.
Answer
- When conc. HNO3 is added to copper, a reddish brown gas (NO2) having pungent smell is evolved.
19. Action of nitric acid on limestone.
Answer
Carbon dioxide gas is liberated when nitric acid reacts with limestone.
CaCO3 + 2HNO3 ⎯→ Ca(NO3)2 + H2O + CO2 ↑
20. Action of heat on concentrated nitric acid.
Answer
When conc. HNO3 is heated, it rapidly decomposes to reddish brown nitrogen dioxide gas along with the formation of water and oxygen gas
21. Nitric acid comes in contact with skin.
Answer
The acid produces yellow stain on skin and wood, since skin and wood contain protein.
The protein reacts with nitric acid to produce xanthoproteic complex compound. This compound is yellow in colour.
22. An aqueous solution of KI(aq) is added to HNO3.
Answer
When HNO3 is added to KI(aq), it is oxidised to Iodine. During the reaction, violet colour vapours of iodine is observed.
23. Hot and conc. nitric acid is added to sulphur.
Answer
A dense brown fumes of nitrogen dioxide (NO2) gas are evolved
Balancing/Writing the Chemical Equations
(a) Write balanced chemcial equation for the following :
1. Reaction of hydrogen chloride with ammonia.
Answer
HCl + NH3 ⎯→ NH4Cl.
2. The preparation of ammonia from ammonium chloride and calcium hydroxide.
Answer
2NH4Cl + Ca(OH)2 ⎯→ CaCl2 + 2NH3 + 2H2O
Calcium Ammonia water
chloride
3. Magnesium heated in nitrogen.
Answer
3Mg + N2 ⎯→ Mg3N2
Magnesium nitrite
4. Action of concentrated nitric acid an copper.
Answer
Cu + 4HNO3 ⎯→ Cu(NO3)2 + 2H2O + 2NO2 ↑
Nitric acid Copper(II)
nitrate
5. Action of heat on silver nitrate.
Answer
6. Reaction of nitric acid with sodium bicarbonate.
Answer
NaHCO3 + HNO3 ⎯→ NaOH + H2O + CO2 ↑
7. Laboratory preparation of nitric acid.
Answer
8. Chlorine reacts with excess of ammonia.
Answer
3Cl2 + 8NH3 ⎯→ 6NH4Cl + N2
Ammonium chloride
9. Ferric hydroxide reacts with nitric acid.
Answer
Fe(OH)3 + 3HNO3 ⎯→ Fe(NO3)3 + 3H2O
Iron(III) nitrate
10. Action of heat on ammonium nitrate.
Answer
11. Dilute nitric acid producing carbon dioxide.
Answer
12. Reaction between copper and concentrated nitric acid.
Answer
13. Burning of ammonia in oxygen.
Answer
14. Catalytic oxidation of ammonia.
Answer
15. Action of heat on ammonium chloride
Answer
16. Copper and concentrated nitric acid.
Answer
17. Copper oxide and dilute nitric acid.
Answer
18. Action of conc. HNO3 on sulphur.
Answer
19. Action of conc. HNO3 on phosphorus.
Answer
20. Action of conc. HNO3 on carbon.
Answer
21. Action of conc. HNO3 on iodine.
Answer
22. Dilute nitric acid and copper.
Answer
23. Ammonia with lead oxide.
Answer
24. Ammonia with copper oxide.
Answer
25. Ammonia with excess chlorine.
Answer
26. Action of water in magnesium nitride.
Answer
Chemical Tests
1. Dilute hydrochloric acid and dilute nitric acid.
Answer
Silver nitrate solution when added to dil. hydrochloric acid will give a white ppt. and when added to dil. nitric acid no change will be observed.
2. Ammonium ion and hydroxide ion.
Answer
When iron(II) sulphate solution is added to ammonium ion, dirty green precipitate is obtained. No change will be observed with hydroxide ion.
3. Nitric oxide gas and nitrous oxide gas.
Answer
If reddish brown fumes are produced in the atmosphere of oxygen then the given sample of gas is nitric oxide and if no brown fumes are produced and the mixture remains colourless, then the gas is nitrous oxide.
4. Dilute hydrochloric acid and dilute sulphuric acid.
Answer
Dilute sulphuric acid will give a white precipitate of barium sulphate with barium chloride solution whereas no visible reaction occurs with dilute hydrochloric acid.
5. Oxygen gas and nitrous oxide gas.
Answer
Carbon (red hot) burns in oxygen to form carbon dioxide gas only, but in nitrous oxide it forms carbon dioxide gas and nitrogen.
Reasoning Based Questions
Q. 1. Ammonia cannot be obtained in laboratory from ammonium nitrate and sodium hydroxide. Why ?
Answer
Ammonia cannot be obtained in laboratory from ammonium nitrate and sodium hydroxide because ammonium nitrate on heating decomposes explosively with the formation of nitrous oxide and water.
Q. 2. Why ammonia gas is not collected over water ?
Answer
Ammonia gas is not collected over water because it is highly soluble in water.
Q. 3. Ammonia cannot be dried by bubbling through concentrated sulphuric acid. Why ?
Answer
Ammonia gas cannot be dried by bubbling through concentrated sulphuric acids as it reacts with sulphuric acid to form ammonium sulphate.
2NH3 + H2SO4 ⎯→ (NH4)2SO4
Q. 4. Quick lime is the only drying agent used for drying ammonia gas. Why ?
Answer
Quick lime is basic in nature and hence does not react with ammonia, which is also basic in nature, whereas all other drying agents are acidic in nature and hence react with ammonia.
2NH3 + H2SO4 ⎯→ (NH4)2SO4
(conc.)
CaCl2 + 8NH3 ⎯→ CaCl2.8NH3
(anhydrous)
6NH3 + P2O5 + 3H2O ⎯→ 2(NH4)3.PO4
Q. 5. Aqueous solution of ammonia gives a pungent smell. Why ?
Answer
Aqueous solution of ammonia gives a pungent smell because it is produced due to bacterial decomposition of urea (NH2CONH2), present in urine.
Q. 6. Ammonia solution is used as laboratory reagent to identify metal ions. Why ?
Answer
Ammonium hydroxide can precipitate insoluble hydroxide of metals from their salt solutions. Thus, it is used in analytical analysis of salts in laboratory.
Q. 7. Aqueous solution of ammonia turns red litmus blue. Give reason.
Answer
This is because ammonia on dissolving in water furnishes ammonium (NH+4) ions and hydroxyl (OH–) ions. The presence of OH – ions in the solution turns red litmus blue.
NH3 + H2O ⇌ NH+4 + OH–
Short Answer
Q. 1. How liquor ammonia is different from liquid ammonia ?
Answer
A very strong solution of ammonia in water is called liquor ammonia. Ammonia can be obtained from it by boiling. When ammonical liquor is boiled with milk of lime, the ammonia formed is passed into ice or cold water to form liquor ammonia.
When cooled under pressure, ammonia condenses to a colourless liquid which boils at – 33·4°C. This is liquid ammonia which when further cooled freezes to a white crystalline snow like solid, which melts at – 77·7°C. Liquid ammonia is used as a refrigerant because its heat of vaporisation is 5700 calories per gram molecule. Liquid ammonia is liquified ammonia and is available in cylinders. Laboratory bench reagent is a diluted solution of liquor ammonia.
Q. 2. The questions below are related to the manufacture of ammonia.
(i) Name the process.
(ii) In what ratio must the reactants be taken ?
(iii) Name the catalyst used.
(iv) Give the equation for the manufacture of ammonia.
(v) Ammonia can act as a reducing agent — write a relevant equation for such a reaction.
Answer
(i) Haber’s process.
(ii) Nitrogen one part, hydrogen three parts.
(iii) Iron powder.
(iv) N2 + 3H2 ⎯→ 2NH3
(v) 2NH3 + 3CuO ⎯→ 3Cu + 3H2O + N2
Copper Copper
oxide
Q. 3. The following questions are based on the preparation of ammonia gas in the laboratory :
(i) Explain why ammonium nitrate is not used in the preparation of ammonia.
(ii) Name the compound normally used as a drying agent during the process.
(iii) How is ammonia gas collected ?
(iv) Explain why it is not collected over water.
(v) Give the name of a hydride of nitrogen.
(vi) Which reactants are used in laboratory preparation of ammonia ?
(vii) What is the vapour density and nature of ammonia ?
(viii) Which feature of the Ammonia molecules leads to the formation of the ammonium ion when ammonia dissolves in water. Name the other ion formed when ammonia dissolves in water.
Answer
(i) Ammonium nitrate is not used in the preparation of ammonia because ammonium nitrate is explosive in nature and dissociate into nitrous oxide and water on heating.
(ii) Quick lime.
(iii) By downward displacement of air.
(iv) It is highly soluble in water.
(v) Ammonia.
(vi) Ammonium chloride and slaked lime [Ca(OH)2].
(vii) Vapour density of ammonia is 8·5, and it is alkaline in nature.
(viii) In ammonia molecule there is one lone pair of electrons available on nitrogen atom. This lone pair of electron leads to the formation of ammonium ion. Hydroxide ion (OH–), is
formed when ammonia dissolves in water.
Q. 4. What are the necessary conditions for getting maximum yield of ammonia ?
Answer
The necessary conditions for getting maximum yield of ammonia are as follows :
(i) Low Temperature : As the reaction is exothermic in nature, so the temperature should be low. When temperature is lowered, the rate of the reaction slows down and the yield is maximum. It is found for maximum yield, temperature should be between 450° to 500°C (optimum temperature).
(ii) Catalyst : A catalyst is used to accelerate the reaction at optimum temperature. Following are the catalysts used :
(a) Finely divided iron, mixed with molybdenum as promoter.
(b) A better catalyst is ferric oxide (Fe2O3) containing 1% of potassium oxide (K2O) and
3% of aluminium oxide (Al2O3) which acts as promoters.
(iii) High Pressure : When 4 volumes of a mixture of nitrogen and hydrogen are reduced to 2 volumes of ammonia, the pressure drops. In order to have maximum yield the pressure should be very high. The optimum pressure should be between 200 atmospheres to 900 atmospheres.
(iv) Purity of Gases : Any kind of impurity tends to slow down the reaction or poisons catalyst. So, the gases that are to be used should be pure and dry.
Q. 5. (i) What are the products formed when ammonia is oxidised with copper oxide ?
(ii) What is the difference between chemical nature of an aqueous solution of hydrogen chloride and an aqueous solution of ammonia.
Answer
(i) Nitrogen, copper and water.
(ii) Aqueous solution of HCl is acidic while aqueous solution of ammonia is basic.
Q. 6. How would you prepare :
(i) Nitrogen from ammonia. (ii) Ammonia from nitrogen.
(iii) Nitric oxide gas and nitrous oxide gas.
Answer
(i) Ammonia gas burns in the presence of oxygen in a glass jar with a greenish yellow flame
to form nitrogen and steam.
4NH3 + 3O2 ⎯→ 2N2 + 6H2O
(ii) Nitrogen combines with heated metals; for example, aluminium to form aluminium
nitride, which is readily decomposed by water to form ammonia gas which has a characteristic pungent odour and aluminium hydroxide is also formed.
2Al + N2 ⎯→ 2AlN
Aluminium nitride
AlN + 3H2O ⎯→ Al(OH)3 + NH3
Aluminium
hydroxide
(iii) Introduce the given gas in the atmosphere of oxygen and if reddish brown fumes are produced, then the given sample of gas is nitric oxide and if no brown fumes are
produced and the mixture remains colourless, then the gas is nitrous oxide.
Q. 7. Outline the conditions of the synthetic process for producing ammonia gas. Mention the catalyst used.
Answer
A mixture of nitrogen and hydrogen in the ratio of 1 : 3 by volume is passed over heated iron at 450°C in the presence of molybdenum, which acts as catalyst (promoter) under 200 atmospheric pressure. The reaction of nitrogen and hydrogen is a reversible reaction hence ammonia is removed from the reaction vessel from time to time by liquefaction under high pressure, so that the reaction proceeds in the forward direction.
N2 + 3H2 ⇌ 2NH3 + 22 k cal.
Ammonia
Q. 8. Name one element in each case, to which the following description would apply.
(i) The burning metal which combines directly with nitrogen.
(ii) Define fixation of nitrogen and state two ways in which fixation of nitrogen occurs, naturally.
(iii) Give two reasons to show that the solution of ammonia in water contains hydroxide ions.
Answer
(i) Magnesium, calcium and aluminium.
(ii) Conversion of atmospheric nitrogen into soluble nitrogenous compounds which can be easily absorbed by the roots of the plants.
(a) During thunder and lightning
(b) By symbiotic bacteria
(iii) (a) It turns red litmus solution to blue.
(b) It reacts with acids to form salt and water.
Q. 9. (i) Of the two gases, ammonia and hydrogen chloride, which is more dense ? Name the method of collection of this gas.
(ii) Give one example of a reaction between the above two gases which produces a solid compound.
Answer
(i) HCl collected by upward displacement of air.
(ii) NH3 + HCl ⎯→ NH4Cl
Q. 10. (i) Does ammonia burn in oxygen ? If yes, give equation.
(ii) What is catalytic oxidation of ammonia ?
(iii) What is the special feature of the apparatus that is used in the laboratory preparation of nitric acid ?
(iv) Why should the temperature of the reaction mixture of nitric acid not be allowed to rise above 200°C ?
Answer
(i) Yes. Ammonia burns in oxygen with a greenish yellow flame producing water vapour and nitrogen.
4NH3 + 3O2 ⎯→ 2N2 + 6H2O
(ii) Ammonia, when reacts with oxygen in presence of platinum (as catalyst) at 800°C, ammonia is oxidised to nitric oxide (NO). This is called catalytic oxidation of ammonia.
(iii) It is an all glass retort.
(iv) Because above 200°C nitric acid will decompose.
