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Class 10 SELINA Solutions Chemistry Chapter 9 - Study of Compounds B. Ammonia

Study of Compounds B. Ammonia Exercise Intext 1

Solution 1(a)

Covalent bonding is present in ammonia.

Solution 1(b)

Formula of liquid ammonia is: NH3.

Liquid ammonia is liquefied ammonia and is basic in nature. It dissolves in water to give ammonium hydroxide which ionizes to give hydroxyl ions.

NH3 + H2O NH4OH

NH4OH NH4++ OH-

Therefore it turns red litmus blue and phenolphthalein solution pink.

Solution 2

(a) Lab preparation of ammonia:

2NH4Cl+Ca(OH)2 CaCl2 +2H2O +2NH3

(b) The ammonia gas is dried by passing through a drying tower containing lumps of quicklime (CaO).

(d) Ammonia is highly soluble in water and therefore it cannot be collected over water.

Solution 3

(a) An aqueous solution of ammonia is prepared by dissolving ammonia in water. The rate of dissolution of ammonia to water is very high.

Diagram:

(b)The drying agent used is CaO in case of ammonia.

Other drying agents like P2O5 and CaCl2 are not used. As ammonia being basic reacts with them.

6NH3 + P2O5 +3H2O 2(NH4)3PO4

CaCl2 +4NH3 CaCl2.4NH3

Solution 4

The substance A is Ammonium chloride and 'B' is Ammonia.

Reaction:

2NH4Cl + Ca(OH)2 CaCl2 + 2H2O + 2NH3

Solution 5

(a) Conditions for reactants to combine :

Optimum temperature is 450o-500oC

Above 200 atm pressure

Finely divided iron as catalyst

Traces of molybdenum or Al2O3 as promoters.

Reaction:N2 +3H2 2NH3 + heat

(b) Dry nitrogen and dry hydrogen in the ratio of 1:3 by volume is made to combine.

(c) Source of Hydrogen: Hydrogen is generally obtained from water gas by Bosch process.

(CO + H2) + H2O CO2 +2H2

Source of Nitrogen: It is obtained from fractional distillation of liquid air.

(d) High pressure favours the forward reaction i.e. formation of ammonia.

(e)Two possible ways by which NH3 produced is removed from unreacted N2 and H2 by:

(i)Liquefaction: NH3 is easily liquefiable.

(ii)Absorbing in water: As ammonia is highly soluble in water.

(f)

(i)Finely divided iron increases the rate of reaction.

(ii)Molybdenum acts as a promoter to increase the efficiency of the catalyst.

 

(g) 15%

(h) The unchanged nitrogen and hydrogen are recirculated through the plant to get more ammonia. By recirculating in this way, an eventual yield of 98% can be achieved.

Solution 6

(a) Ammonium compounds being highly soluble in water do not occur as minerals.

(b) Ammonium nitrate is not used in the preparation of ammonia as it is explosive in nature and it decomposes forming nitrous oxide and water vapours.

(c) Conc. H2SO4 is not used to dry ammonia, as ammonia being basic reacts with them.

2NH3 + H2SO4 (NH4)2SO4

(d)  (i) In order to better mixing of ammonium chloride, calcium hydroxide used in excess.

       (ii) The flask is fitted in slatting position because of the water formed in the reaction does not trickle back into the heated flask.

Solution 7

a.

 

Name of process

Inputs

Equations

Output

Haber's process

Nitrogen and hydrogen

 straight N subscript 2 space plus space 3 straight H subscript 2 space rightwards harpoon over leftwards harpoon from 450 to the power of 0 straight C minus 500 to the power of 0 straight C space less than 200 atm to Fe space and space Mo of space space 2 NH subscript 3 space plus space Heat

Ammonia

 




b. 

 i. 450 - 500°C

 ii. 200 -800 atm

 iii. Finely divided iron (Fe)

Solution 8

a. Neutralisation

b. Thermal decomposition

c. Ammonia

Solution 9

An element has 2 electrons in its N shell = Ca (calcium)

It reacts with a non-metal of atomic number 7 = N (nitrogen)

The compound formed is calcium nitride (Ca3N2) which reacts with warm water and produces the basic gas ammonia (NH3).

Solution 10

(a) The formula of the compound is Mg3N2.

(b) Balanced equation :

Mg3N2 + 6 H2O  3 Mg(OH)2 + 2 NH3

(c) Ammonia is a reducing agent and reduces less active metal oxide to its respective metal.

Solution 11

a. A reddish brown precipitate is obtained when ammonium hydroxide is added to ferrous chloride.

b. Aqueous ammonia is a solution of NH3.

c. Finely divided iron is used in Haber process.

d. Quicklime (CaO) is a drying agent for NH3.

e. Ammonium salts, on thermal decomposition, give ammonia and hydrogen chloride.

Solution 12

C.: Magnesium nitride

Study of Compounds B. Ammonia Exercise Ex. 9

Solution 1

(a)Ammonia is less dense than air. By Fountain Experiment, we demonstrate the high solubility of ammonia gas in water.

(b) The high solubility of ammonia gas in water

(c)The balanced equation for the reaction between ammonia and sulphuric acid is:

2NH3 + H2SO4 (NH4)2SO4

Solution 2

(a) Ammonia is basic in nature.

(b) Copper oxide because CuO is less reactive can be reduced by C, CO or by hydrogen whereas Al2O3, Na2O, MgO are reduced by electrolysis.

Solution 3

(a) Liquid ammonia acts as a refrigerant in ice plants. Evaporation needs heat energy, and when liquid ammonia vaporises, it absorbs large quantities of heat without changing its temperature. For these reasons, ammonia is widely used as a refrigerant.

(b) Ammonia is used for removing grease and dirt as it emulsifies or dissolves them.

(c) Ammonia is formed by bacterial decomposition of urea, so ammonia has a pungent smell.

(d) An aqueous solution of ammonia is a weak electrolyte. It dissociates partially to give hydroxyl ions, and ions conduct electricity. So an aqueous solution of ammonia conducts electricity.

Solution 4

(a) The gas is ammonia.

(b) The formula is NH3.

(c) Uses of ammonia:

It is used in the industrial preparation of nitric acid by Ostwald process.

It is used in the manufacture of fertilizers such as ammonium sulphate, ammonium nitrate, ammonium phosphate.

It is used in the manufacture sodium carbonate by Solvay process.

NaCl + NH3 + CO2 + H2O NaHCO3 +NH4Cl

Solution 5

Equation:

CuSO4 +2NH4OH Cu(OH)2 + [NH4]2SO4

pale blue

Ammonia solution in water gives a blue precipitate when it combines with a solution of copper salt.

The pale blue precipitate of copper hydroxide dissolves in excess of ammonium hydroxide forming tetraamine copper[II] sulphate, an azure blue(deep blue)soluble complex salt.

Cu(OH)2 +(NH4)2SO4 +2NH4OH [Cu(NH3)4]SO4 + 4H2O

Solution 6

This reaction is reversible and exothermic. From the reaction, it is proved that ammonia contains nitrogen and hydrogen.

Also,

  

Ammonia burns with a yellowish flame. It produces water vapour and nitrogen. This shows that ammonia contains nitrogen and hydrogen.

Solution 7

(a) AlN + 3H2O Al(OH)3 +NH3

(b) 2NH3 + 3PbO 3Pb + 3H2O + N2

(c) 8NH3 +3Cl2 N2 + 6NH4Cl

(d) 2NH3 + CO2 NH2CONH2 + H2O

(i) Ammonia act as reducing agent is explained by equation (c).

(ii) Urea the nitrogenous fertilizer is prepared from equation (d).

Solution 8

(a) Dirty green ppt. of Ferrous hydroxide is formed which is insoluble in excess of NH4OH.

FeSO4 + 2NH4OH [NH4]2SO4 + Fe(OH)2

(b) Reddish brown ppt. of ferric hydroxide is formed which is insoluble in ammonium hydroxide.

FeCl3 + 3NH4OH 3NH4Cl + Fe(OH)3

(c) White ppt. of lead hydroxide is formed which is insoluble in NH4OH.

Pb(NO3)2 + 2NH4OH 2NH4NO3 + Pb(OH)2

(d)White gelatinous ppt. of Zinc hydroxide is formed which is soluble in NH4OH.

Zn(NO3)2 + 2NH4OH 2NH4NO3 + Zn(OH)2

Solution 9

  1. Calcium chloride and zinc chloride

Calcium chloride does not react with ammonium hydroxide.

On adding ammonium hydroxide drop by drop to a solution of zinc salt a white precipitate is formed which is soluble in excess of ammonium hydroxide.

 

  1. Ferric salt and ferrous salt:

When ammonium hydroxide is added drop wise to solution to be tested.

Ferrous salt gives dirty green ppt.

Ferric salt gives reddish brown ppt of their hydroxides.

 

  1. Zinc nitrate and lead nitrate

When ammonium hydroxide is added drop wise to solution to be tested.

Zinc nitrate gives white gelatinous ppt. of their hydroxides which is soluble on adding excess of ammonium hydroxide.

Whereas, lead nitrate gives white ppt. of their hydroxides which is insoluble on adding excess of ammonium hydroxide.

Solution 10

  1. 8NH3 + 3Cl2 → N2 + 6NH4Cl
  2. 4NH3 + 5O2    4NO + 6H2O + Heat

2NO + O2 → 2NO2

  1. NH3 + 3Cl2 → 3HCl + NCl3
  2. AlCl3 + 3NH4OH → 3NH4Cl + Al(OH)3
  3. AlN + 3H2O →  Al(OH)3 + NH3
  4. 3PbO + 2 NH3   3Pb + 3H2O + N2

Solution 11

(a) Ammonia

(b) Hydrogen chloride and chlorine gas.

(c) (i) Ammonium chloride

(i) Ammonium nitrate

(ii) Ammonium carbonate

(d) Acidic gas: HCl

Basic gas: Ammonia

Neutral gas: NH4Cl

(e) Silver chloride

(f) Nitrogen

(g) Magnesium nitride

(h) Lead oxide

(i) Ammonium chloride

Solution 12

CuSO4 + 2NH4OH (NH4)2SO4 +Cu(OH)2 [Pale blue]

The cation present in solution B is Copper (Cu+2).

The colour of solution B is Blue.

The pale blue precipitate of copper hydroxide dissolves in excess of ammonium hydroxide forming tetraamine copper[II] sulphate, an azure blue(deep blue) soluble complex salt.

Cu(OH)2 + (NH4)2SO4 +2NH4OH [Cu(NH3)4]SO4 + 4H2O

Solution 13

Three ways in which ammonia gas can be identified is:

It has a sharp characteristic odour

When a glass rod dipped in HCl is brought in contact with the gas white colour fumes of ammonium chloride are formed

It turns moist red litmus blue, moist turmeric paper brown and phenolphthalein solution pink.

Solution 14

As the 'A' turns red litmus blue it is a base.Now the gas 'A' combines with 'B' in presence of Catalyst to give colourless gas Nitrogen monoxide. It reacts with oxygen to give brown gas which is Nitrogen dioxide.

A= NH3

B= O2

C=NO

D=NO2

Reactions:

4NH3 + 5O2 4NO + 6H2O + Heat

2NO + O2 2NO2

NH3 in water forms NH4OH which turns red litmus blue.

Solution 15

(a) The main refrigerants used are Freon chlorofluorocarbons (CFC). They deplete ozone layer. The chlorofluorocarbons are decomposed by ultraviolet rays to highly reactive chlorine which is produced in the atomic form.

begin mathsize 14px style CF subscript 2 Cl subscript 2 left parenthesis straight g right parenthesis rightwards arrow with space space space space space ultraviolet space space space space space space on top CF subscript 2 Cl left parenthesis straight g right parenthesis plus left parenthesis straight g right parenthesis
space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space space free space radical end style

The free radical [Cl] reacts with ozone and chlorine monoxide is formed.

begin mathsize 14px style Cl left parenthesis straight g right parenthesis plus straight O subscript 3 left parenthesis straight g right parenthesis rightwards arrow with space space space space space space space space space space space space space space space space space space space space space on top ClO left parenthesis straight g right parenthesis plus straight O subscript 2 left parenthesis straight g right parenthesis end style

This causes depletion of ozone layer and chlorine monoxide so formed reacts with atomic oxygen and produces more chlorine free radicals.

ClO + Orightwards arrowCl + O2

Again this free radical destroys ozone and the process continues thereby giving rise to ozone depletion.

(b) Liquid ammonia can be used as a refrigerant, as an alternative for chlorofluorocarbons.

(c) Advantages of ammonia as refrigerant:

(i) Ammonia is environmentally compatible. It does not deplete ozone layer and does not contribute towards global warming.

(ii) It has superior thermodynamic qualities as a result ammonia refrigeration systems use less electricity.

Ammonia has a recognizable odour and so leaks are not likely to escape.

Solution 16

(a) Explosive: ammonium nitrate

(b) Medicine: ammonium carbonate

(c) Fertilizers: ammonium sulphate

(d) Laboratory reagent: ammonia solution

Solution 17

(a) Ammonium chloride

NH4Cl NH3 +HCl

(b) Ammonium nitrate

NH4NO3 N2O +2H2O

Both are examples of Thermal dissociation.

Solution 18

(a)It is the basic nature of ammonia molecule.

(b)Hydroxyl ion (NH3 +H2O NH4+ + OH-)

(c) The red litmus paper turns blue in the solution.

Solution 19

(a) HCl gas is more dense [V.D.=18.25,V.D. of ammonia =8.5] and it is collected by the upward displacement of air.

(b) NH3 + HCl → NH4Cl

(c) Balanced equation:

(a) 2NH3 +3CuO 3Cu +3H2O +N2

(b) 2NH3 +3Cl2 N2 + 6HCl

Solution 20

A. Mg3N2 + 6H2O → 3Mg(OH)2 + 2NH3

B. NH3 + HCl → NH4Cl

Or

8NH3 + 3Cl2 → 6NH4Cl + N2

C. NH4Cl + NaOH → NaCl + NH3 + H2O

Solution 21

  1. Ammonia reacts with excess chlorine to form nitrogen trichloride.
  2. Ammonium hydroxide is added to ferrous sulphate solution.
    2NH4OH + FeSO4 Fe(OH)2 ↓ + (NH4)2SO4
  1. When ammonia gas is passed over heated copper (II) oxide, black copper oxide is reduced to greyish metallic copper.

Solution 2008

a. 

b. C.: Magnesium nitride

Solution 2009

a. Ammonia

b.  .

c. 'Q' is ammonium chloride.

Solution 2010

a. 

 i. Ammonia

 ii. Alkaline

 iii. Ammonium

 iv. Hydroxyl

 v. Dirty green

b. Ammonia burns with a yellowish flame. It produces water vapour and nitrogen.

c. 

d. 

 i. Haber's process

 ii. 1 part of nitrogen gas and 3 parts of hydrogen gas

 iii. Finely divided iron (Fe)

 iv. 

e. 

f. 

 i. Ammonia and hydrogen chloride gas

 ii. High solubility of gases in water

Solution 2011

a. In small quantity: A bluish white ppt. is obtained.

In excess quantity: A deep blue solution is obtained.

 

b. 

 i. Ammonia

 ii. 

 iii. By downward displacement of air

 iv. Quicklime/CaO

 v. Bring a moist red litmus paper to the mouth of  the inverted jar if it immediately turns blue.

 Or

Bring a glass rod dipped in hydrochloric acid to the mouth of the inverted jar. If it produces dense white fumes, then the jar is full of gas.

c. 

d. Pungent smelling basic gas called ammonia is evolved.

Solution 2012

a. Nitrogen

b. Magnesium nitride reacts with boiling water to liberate ammonia.

c. 

d. 

 i. Ammonium nitrate is a highly explosive substance and cannot be heated.

 ii. Quicklime/CaO

 iii. By the downward displacement of air or upward delivery as it is lighter than air.

It is not collected over water because it easily dissolves in water.

Solution 2013

a. A yellow-coloured explosive is formed.

b. Ammonium nitrite

c. 

 i. When added in small quantity, it forms a gelatinous white ppt.

 ii. When added in excess, it dissolves to form a complex salt.

d. 

e.  

Name of the process

Temperature

Catalyst

Equation for the catalysed reaction

Haber's process

450-500°C

Finely divided iron (Fe)

f.  Ammonia

Solution 2014

a. Downward displacement of air.

b. 

c. 

 i. Iron(II) sulphate: Gives dirty green ppt. with ammonium hydroxide insoluble in excess.

 ii. Iron(III) sulphate: Gives reddish brown ppt. with ammonium hydroxide insoluble in excess.

d. A colourless pungent-smelling ammonia gas is obtained.

e. 

 i. Hydroxyl (OH-) ion other than ammonium ion

 ii. Red litmus turns blue, methyl orange turns yellow and phenolphthalein turns pink.

f. In the presence of platinum catalyst at 800°C.

Solution 2015

(a)  

(i)  2NH4Cl + Ca (OH)2  CaCl2 + 2H2O + 2NH3 

(ii) NH3 + 3Cl2 NCl3 + 3HCl

  (Nitrogen trichloride)

(iii) 2NH3 + H2SO4 (NH4)2SO4

     Ammonium sulphate

(b) Ammonia (NH3)

Solution 2016 (a)

(i) Ammonia

(ii) Nitrogen 

Solution 2016 (b)

(i) 8NH3 + 3Cl2 N2 + 6NH4Cl 

(ii) 3PbO + 2NH33Pb + 3H2O + N2 

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