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NCERT solutions Chemistry Class 11 Part 1 chapter 7 Equilibrium

Chapters

NCERT Solutions for Chemistry Class 11 Part 2

NCERT Chemistry Class 11 Part 1

Chemistry Textbook for Class 11 Part 1

Chapter 7 - Equilibrium

Pages 24 - 230

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

What is the initial effect of the change on vapour pressure?

Q 1.1 | Page 224

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

How do rates of evaporation and condensation change initially?

Q 1.2 | Page 224

A liquid is in equilibrium with its vapour in a sealed container at a fixed temperature. The volume of the container is suddenly increased.

 What happens when equilibrium is restored finally and what will be the final vapour pressure?

Q 1.3 | Page 224

What is Kc for the following equilibrium when the equilibrium concentration of each substance is: [SO2]= 0.60 M, [O2] = 0.82 M and [SO3] = 1.90 M ?

2SO2(g) + O2(g) ⇌2SO3(g)` 

Q 2 | Page 24

At a certain temperature and total pressure of 10Pa, iodine vapour contains 40% by volume of I atoms

I_2 (g) ↔ 2I(g)

Calculate Kpfor the equilibrium.

Q 3 | Page 224

Write the expression for the equilibrium constant, Kc for each of the following reactions:

2NOCl (g) ⇌ 2NO (g) + Cl2 (g)

Q 4.1 | Page 224

Write the expression for the equilibrium constant, Kc for the following reactions:

2Cu(NO3)2 (s) ⇌ 2CuO (s) + 4NO2 (g) + O2 (g)

Q 4.2 | Page 224

Write the expression for the equilibrium constant, Kc for the following reactions:

CH3COOC2H5(aq) + H2O(l) ⇌CH3COOH (aq) + C2H5OH (aq)

Q 4.3 | Page 224

Write the expression for the equilibrium constant, Kc for following reactions:

Fe3+ (aq) + 3OH (aq) ⇌ Fe(OH)3 (s)

Q 4.4 | Page 224

Write the expression for the equilibrium constant, Kc for the following reactions

I2 (s) + 5F2 ⇌ 2IF5

Q 4.5 | Page 224

Find out the value of Kc for each of the following equilibria from the value of Kp:

2NOCl (g) ⇌ 2NO (g) + Cl2 (g); Kp= 1.8 × 10–2 at 500 K

Q 5.1 | Page 224

Find out the value of Kc for each of the following equilibria from the value of Kp:

CaCO3 (s) ⇌ CaO(s) + CO2(g); Kp= 167 at 1073 K

Q 5.2 | Page 224

For the following equilibrium, Kc= 6.3 × 1014 at 1000 K

NO (g) + O3 (g) ⇌NO2 (g) + O2 (g)

Both the forward and reverse reactions in the equilibrium are elementary bimolecular reactions. What is Kc, for the reverse reaction?

Q 6 | Page 224

Explain why pure liquids and solids can be ignored while writing the equilibrium constant expression?

Q 7 | Page 225

A reaction between N2 and O2 takes place as follows:

2N2 (g) + O2 (g) ⇌ 2N2O (g)

If a mixture of 0.482 mol of N2 and 0.933 mol of O2 is placed in a 10 L reaction vessel and allowed to form N2O at a temperature for which Kc = 2.0 × 10–37, determine the composition of equilibrium mixture.

 

Q 8 | Page 225

Nitric oxide reacts with Br2 and gives nitrosyl bromide as per reaction given below:

2NO (g) + Br2 (g) ⇌ 2NOBr (g)

When 0.087 mol of NO and 0.0437 mol of Br2 are mixed in a closed container at the constant temperature, 0.0518 mol of NOBr is obtained at equilibrium. Calculate equilibrium amount of NO and Br2 .

Q 9 | Page 225

At 450 K, Kp= 2.0 × 1010/bar for the given reaction at equilibrium.

2SO2(g) + O2(g) ⇌2SO3 (g)

What is Kc at this temperature?

 

Q 10 | Page 225

A sample of HI(g) is placed in flask at a pressure of 0.2 atm. At equilibrium, the partial pressure of HI(g) is 0.04 atm. What is Kp for the given equilibrium?

2HI (g) ⇌ H2 (g) + I2 (g)

Q 11 | Page 225

A mixture of 1.57 mol of N2, 1.92 mol of H2 and 8.13 mol of NH3 is introduced into a 20 L reaction vessel at 500 K. At this temperature, the equilibrium constant, Kc for the reaction N2 (g) + 3H2 (g)⇌2NH3 (g) is 1.7 × 102

Is the reaction mixture at equilibrium? If not, what is the direction of the net reaction?

Q 12 | Page 225

The equilibrium constant expression for a gas reaction is,

`K_c = ([NH_3]^4[O_2]^5)/([NO]^4[H_2O]^6)`

Write the balanced chemical equation corresponding to this expression.

Q 13 | Page 225

One mole of H2O and one mole of CO are taken in 10 L vessel and heated to 725 K. At equilibrium, 40% of water (by mass) reacts with CO according to the equation, H2O (g) + CO (g) ⇌ H2 (g) + CO2 (g). Calculate the equilibrium constant for the reaction.

Q 14 | Page 225

At 700 K, equilibrium constant for the reaction

`H_(2(g)) + I_(2(g)) ↔ 2HI_(g)` is 54.8. If 0.5 molL–1 of HI(g) is present at equilibrium at 700 K, what are the concentration of H2(g) and I2(g) assuming that we initially started with HI(g) and allowed it to reach equilibrium at 700 K?

 

Q 15 | Page 225

What is the equilibrium concentration of each of the substances in the equilibrium when the initial concentration of ICl was 0.78 M?

2 ICl(g) ⇌  I2(g) + Cl2(g) ; KC = 0.14

Q 16 | Page 225

Kp = 0.04 atm at 899 K for the equilibrium shown below. What is the equilibrium concentration of C2H6 when it is placed in a flask at 4.0 atm pressure and allowed to come to equilibrium?

C2H6 (g) ⇌ C2H4 (g) + H2 (g)

Q 17 | Page 225

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

CH3COOH (l) + C2H5OH (l) ⇌CH3COOC2H5 (l) + H2O (l)

Write the concentration ratio (reaction quotient), Qc, for this reaction (note: water is not in excess and is not a solvent in this reaction)

Q 18.1 | Page 226

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

CH3COOH (l) + C2H5OH (l) ⇌CH3COOC2H5 (l) + H2O (l)

At 293 K, if one starts with 1.00 mol of acetic acid and 0.18 mol of ethanol, there is 0.171 mol of ethyl acetate in the final equilibrium mixture. Calculate the equilibrium constant.

Q 18.2 | Page 226

Ethyl acetate is formed by the reaction between ethanol and acetic acid and the equilibrium is represented as:

CH3COOH (l) + C2H5OH (l) ⇌CH3COOC2H5 (l) + H2O (l)

Starting with 0.5 mol of ethanol and 1.0 mol of acetic acid and maintaining it at 293 K, 0.214 mol of ethyl acetate is found after sometime. Has equilibrium  been reached?

Q 18.3 | Page 226

A sample of pure PCl5 was introduced into an evacuated vessel at 473 K. After equilibrium was attained, the concentration of PCl5 was found to be 0.5 × 10–1 mol L–1. If the value of Kc is 8.3 × 10–3, what are the concentrations of PCl3 and Cl2 at equilibrium?

PCl5 (g) ⇌ PCl3 (g) + Cl2(g)

Q 19 | Page 226

One of the reactions that takes place in producing steel from iron ore is the reduction of iron (II) oxide by carbon monoxide to give iron metal and CO2.

FeO (s) + CO (g) ↔ Fe (s) + CO2 (g); Kp= 0.265 at 1050 K.

What are the equilibrium partial pressures of CO and CO2 at 1050 K if the initial partial pressures are: pCO = 1.4 atm and `p_("co"_2)`= 0.80 atm?

Q 20 | Page 226

Equilibrium constant, Kc for the reaction N2 (g) + 3H2 (g) ⇌ 2NH3 (g) at 500 K is 0.061. At a particular time, the analysis shows that composition of the reaction mixture is 3.0 mol L–1 N2, 2.0 mol L–1 H2 and 0.5 mol L–1 NH3. Is the reaction at equilibrium? If not in which direction does the reaction tend to proceed to reach equilibrium?

 

Q 21 | Page 226

At 1127 K and 1 atm pressure, a gaseous mixture of CO and CO2 in equilibrium with solid carbon has 90.55% CO by mass

C (s) + CO2 (g) ⇌ 2CO (g)

Calculate Kc for this reaction at the above temperature.

Q 22 | Page 226

Bromine monochloride, BrCl decomposes into bromine and chlorine and reaches the equilibrium:

2BrCl (g) ⇌ Br2 (g) + Cl2 (g)

for which Kc= 32 at 500 K. If initially pure BrCl is present at a concentration of 3.3 × 10–3 molL–1, what is its molar concentration in the mixture at equilibrium?

Q 22 | Page 226

Calculate a) ΔG°and b) the equilibrium constant for the formation of NO2 from NO and O2 at 298 K

`NO(g) + 1/2 O_2 (g) "↔" NO_2(g)`

where ΔfG° (NO2) = 52.0 kJ/mol

ΔfG° (NO) = 87.0 kJ/mol

ΔfG° (O2) = 0 kJ/mol

Q 24 | Page 226

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)

Q 25.1 | Page 227

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

CaO (s) + CO2 (g) ⇌ CaCO3 (s)

Q 25.2 | Page 227

Does the number of moles of reaction products increase, decrease or remain same when each of the following equilibria is subjected to a decrease in pressure by increasing the volume?

3Fe (s) + 4H2O (g) ⇌ Fe3O4 (s) + 4H2 (g)

Q 25.3 | Page 227

Which of the following reactions will get affected by increasing the pressure? Also, mention whether change will cause the reaction to go into forward or backward direction.

(i) COCl2 (g) ⇌CO (g) + Cl2 (g)

(ii) CH4 (g) + 2S2 (g) ⇌CS2 (g) + 2H2S (g)

(iii) CO2 (g) + C (s) ⇌ 2CO (g)

(iv) 2H2 (g) + CO (g) ⇌ CH3OH (g)

(v) CaCO3 (s) ⇌CaO (s) + CO2 (g)

(vi) 4 NH3 (g) + 5O2 (g) ⇌ 4NO (g) + 6H2O(g)

Q 26 | Page 227

The equilibrium constant for the following reaction is 1.6 ×105 at 1024K

H2(g) + Br2(g) ⇌ 2HBr(g)

Find the equilibrium pressure of all gases if 10.0 bar of HBr is introduced into a sealed container at 1024K

Q 27 | Page 227

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:

CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)

Write as the expression for Kp for the above reaction.

Q 28.1 | Page 227

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:

CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)

How will the values of Kp and composition of equilibrium mixture be affected by

(i) increasing the pressure

(ii) increasing the temperature

(iii) using a catalyst?

Q 28.2 | Page 227

Describe the effect of Addition of H2  on the equilibrium of the reaction: 2H2(g) + CO (g) ⇌CH3OH (g)

Q 29.1 | Page 227

Describe the effect of Addition of CH3OH  on the equilibrium of the reaction: 2H2(g) + CO (g) ⇌CH3OH (g)

Q 29.2 | Page 227

Describe the effect of Removal of CO on the equilibrium of the reaction: 2H2(g) + CO (g) ⇌CH3OH (g)

Q 29.3 | Page 227

Describe the effect of Removal of CH3OH on the equilibrium of the reaction: 2H2(g) + CO (g) ⇌CH3OH (g)

Q 29.4 | Page 227

At 473 K, equilibrium constant Kc for decomposition of phosphorus pentachloride, PCl5is 8.3 ×10-3. If decomposition is depicted as,

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)  ΔrH° = 124.0 kJmol–1

Write an expression for Kfor the reaction.

Q 30.1 | Page 227

At 473 K, equilibrium constant Kc for decomposition of phosphorus pentachloride, PCl5is 8.3 ×10-3. If decomposition is depicted as,

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)  ΔrH° = 124.0 kJmol–1

What is the value of Kc for the reverse reaction at the same temperature?

Q 30.2 | Page 227

At 473 K, equilibrium constant Kc for decomposition of phosphorus pentachloride, PCl5 is 8.3 ×10-3. If decomposition is depicted as,

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)  ΔrH° = 124.0 kJmol–1

What would be the effect on Kc if (i) more PCl5 is added (ii) pressure is increased? (iii) The temperature is increased?

Q 30.3 | Page 227

Dihydrogen gas used in Haber’s process is produced by reacting methane from natural gas with high-temperature steam. The first stage of two-stage reaction involves the formation of CO and H2. In the second stage, CO formed in the first stage is reacted with more steam in water gas shift reaction,

CO (g) + H2O (g) ⇌ CO2 (g) + H2 (g)

If a reaction vessel at 400°C is charged with an equimolar mixture of CO and steam such that CO H2O p = p = 4.0 bar, what will be the partial pressure of H2 at equilibrium? Kp= 10.1 at 400°C

Q 31 | Page 228

Predict which of the following reaction will have the appreciable concentration of reactants and products:

a) Cl2 (g) ⇌ 2Cl (g) Kc = 5 ×10–39

b) Cl2 (g) + 2NO (g) ⇌ 2NOCl (g) Kc = 3.7 × 108

c) Cl2 (g) + 2NO2 (g) ⇌ 2NO2Cl (g) Kc = 1.8

Q 32 | Page 228

The value of Kc for the reaction 3O2 (g) ↔ 2O3 (g) is 2.0 ×10–50 at 25°C. If the equilibrium concentration of O2 in the air at 25°C is 1.6 ×10–2, what is the concentration of O3?

 

Q 33 | Page 228

The reaction, CO(g) + 3H2(g) ↔ CH4(g) + H2O(g) is at equilibrium at 1300 K in a 1L flask. It also contains 0.30 mol of CO, 0.10 mol of H2 and 0.02 mol of H2O and an unknown amount of CH4 in the flask. Determine the concentration of CH4 in the mixture. The equilibrium constant, Kc for the reaction at the given temperature is 3.90.

Q 34 | Page 228

What is meant by the conjugate acid-base pair? Find the conjugate acid/base for the following species:

HNO2, CN, HClO4, F, OH, `CO_3^(2-)`, and S2

Q 35 | Page 228

Which of the followings are Lewis acids? H2O, BF3, H+, and `NH_4^(+)`

Q 36 | Page 228

Write the conjugate acids for the following Brönsted bases: NH2, NH3 and HCOO.

Q 38 | Page 228

The species: H2O,`HCO_3^(-)`,`HSO_4^(-)` and NH3 can act both as Brönsted acids and bases. For each case give the corresponding conjugate acid and base.

Q 39 | Page 228

Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base: 

`OH^(-)`

Q 40.1 | Page 228

Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base:  

F

Q 40.2 | Page 228

Classify the following species into Lewis acids and Lewis bases and show how these act as Lewis acid/base: 

H+ 

Q 40.3 | Page 228

The concentration of hydrogen ion in a sample of soft drink is 3.8 × 10–3 M. what is its pH?

Q 41 | Page 228

The pH of a sample of vinegar is 3.76. Calculate the concentration of hydrogen ion in it.

Q 41 | Page 228

The ionization constant of HF, HCOOH and HCN at 298K are 6.8 × 10–4, 1.8 × 10–4 and 4.8 × 10–9 respectively. Calculate the ionization constants of the corresponding conjugate base.

Q 43 | Page 228

The ionization constant of phenol is 1.0 × 10–10. What is the concentration of phenolate ion in 0.05 M solution of phenol? What will be its degree of ionization if the solution is also 0.01M in sodium phenolate?

Q 44 | Page 228

The first ionization constant of H2­­S is 9.1 × 10–8. Calculate the concentration of HSion in its 0.1 M solution. How will this concentration be affected if the solution is 0.1 M in HCl also? If the second dissociation constant of H2S is 1.2 × 10–13, calculate the concentration of S2– under both conditions.

Q 45 | Page 228

The ionization constant of acetic acid is 1.74 × 10–5. Calculate the degree of dissociation of acetic acid in its 0.05 M solution. Calculate the concentration of acetate ion in the solution and its pH.

Q 46 | Page 229

It has been found that the pH of a 0.01M solution of an organic acid is 4.15. Calculate the concentration of the anion, the ionization constant of the acid and its pKa.

Q 47 | Page 229

Assuming complete dissociation, calculate the pH of the following solutions:

0.003 M HCl

Q 48.1 | Page 229

Assuming complete dissociation, calculate the pH of the following solutions:

0.005 M NaOH 

Q 48.2 | Page 229

Assuming complete dissociation, calculate the pH of the following solutions: 0.002 M HBr

 

Q 48.3 | Page 229

Assuming complete dissociation, calculate the pH of the following solutions:  0.002 M KOH

 

Q 48.4 | Page 229

Calculate the pH of the following solutions: 2 g of TlOH dissolved in water to give 2 litre of solution.

Q 49.1 | Page 229

Calculate the pH of the following solutions:

0.3 g of Ca(OH)dissolved in water to give 500 mL of solution.

Q 49.2 | Page 229

Calculate the pH of the following solutions:  

0.3 g of NaOH dissolved in water to give 200 mL of solution

 

Q 49.3 | Page 229

Calculate the pH of the following solutions:

1mL of 13.6 M HCl is diluted with water to give 1 litre of solution.

Q 49.4 | Page 229

The degree of ionization of a 0.1M bromoacetic acid solution is 0.132. Calculate the pH of the solution and the pKa of bromoacetic acid.

Q 50 | Page 229

The pH of 0.005M codeine (C18H21NO3) solution is 9.95. Calculate its ionization constant and pKb.

Q 51 | Page 229

What is the pH of 0.001 M aniline solution? The ionization constant of aniline can be taken from Table 7.7. Calculate the degree of ionization of aniline in the solution. Also calculate the ionization constant of the conjugate acid of aniline

Q 52 | Page 229

Calculate the degree of ionization of 0.05M acetic acid if its pKa value is 4.74.

How is the degree of dissociation affected when its solution also contains (a) 0.01 M (b) 0.1 M in HCl?

Q 53 | Page 229

The ionization constant of dimethylamine is 5.4 × 10–4. Calculate its degree of ionization in its 0.02 M solution. What percentage of dimethylamine is ionized if the solution is also 0.1 M in NaOH?

Q 54 | Page 229

Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:

 Human muscle-fluid, 6.83

Q 55.1 | Page 229

Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below

Human stomach fluid, 1.2

Q 55.2 | Page 229

Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:

Human blood, 7.38

Q 55.3 | Page 229

Calculate the hydrogen ion concentration in the following biological fluids whose pH are given below:

Human saliva, 6.4.

Q 55.4 | Page 229

The pH of milk, black coffee, tomato juice, lemon juice and egg white are 6.8, 5.0, 4.2, 2.2 and 7.8 respectively. Calculate corresponding hydrogen ion concentration in each.

Q 56 | Page 229

If 0.561 g of KOH is dissolved in water to give 200 mL of solution at 298 K. Calculate the concentrations of potassium, hydrogen and hydroxyl ions. What is its pH?

Q 57 | Page 229

The solubility of Sr(OH)2 at 298 K is 19.23 g/L of solution. Calculate the concentrations of strontium and hydroxyl ions and the pH of the solution.

Q 58 | Page 229

The ionization constant of propanoic acid is 1.32 × 10–5. Calculate the degree of ionization of the acid in its 0.05M solution and also its pH. What will be its degree of ionization if the solution is 0.01M in HCl also?

Q 59 | Page 229

The pH of 0.1M solution of cyanic acid (HCNO) is 2.34. Calculate the ionization constant of the acid and its degree of ionization in the solution.

Q 60 | Page 229

The ionization constant of nitrous acid is 4.5 × 10–4. Calculate the pH of 0.04 M sodium nitrite solution and also its degree of hydrolysis.

Q 61 | Page 229

A 0.02 M solution of pyridinium hydrochloride has pH = 3.44. Calculate the ionization constant of pyridine

Q 62 | Page 230

Predict if the solutions of the following salts are neutral, acidic or basic:

NaCl, KBr, NaCN, NH4NO3, NaNO2 and KF

Q 63 | Page 230

The ionization constant of chloroacetic acid is 1.35 × 10–3. What will be the pH of 0.1M acid and its 0.1M sodium salt solution?

Q 64 | Page 230

Ionic product of water at 310 K is 2.7 × 10–14. What is the pH of neutral water at this temperature?

Q 65 | Page 230

Calculate the pH of the resultant mixtures: 10 mL of 0.2M Ca(OH)2 + 25 mL of 0.1M HCl

Q 66.1 | Page 230

Calculate the pH of the resultant mixtures: 10 mL of 0.01M H2SO4 + 10 mL of 0.01M Ca(OH)2

Q 66.2 | Page 230

Calculate the pH of the resultant mixtures: 10 mL of 0.1M H2SO4 + 10 mL of 0.1M KOH

Q 66.3 | Page 230

Determine the solubilities of silver chromate, barium chromate, ferric hydroxide, lead chloride and mercurous iodide at 298K from their solubility product constants given in Table 7.9 (page 221). Determine also the molarities of individual ions

Q 67 | Page 230

The solubility product constant of Ag2CrO4 and AgBr are 1.1 × 10–12 and 5.0 × 10–13respectively. Calculate the ratio of the molarities of their saturated solutions.

Q 68 | Page 230

Equal volumes of 0.002 M solutions of sodium iodate and cupric chlorate are mixed together. Will it lead to precipitation of copper iodate? (For cupric iodate Ksp = 7.4 × 10–8).

Q 69 | Page 230

The ionization constant of benzoic acid is 6.46 × 10–5 and Ksp for silver benzoate is 2.5 × 10–13. How many times is silver benzoate more soluble in a buffer of pH 3.19 compared to its solubility in pure water?

 
Q 70 | Page 230

What is the maximum concentration of equimolar solutions of ferrous sulphate and sodium sulphide so that when mixed in equal volumes, there is no precipitation of iron sulphide? (For iron sulphide, Ksp = 6.3 × 10–18).

Q 71 | Page 230

What is the minimum volume of water required to dissolve 1g of calcium sulphate at 298 K? (For calcium sulphate, Ksp is 9.1 × 10–6).

Q 72 | Page 230

The concentration of sulphide ion in 0.1M HCl solution saturated with hydrogen sulphide is 1.0 × 10–19 M. If 10 mL of this is added to 5 mL of 0.04 M solution of the following: FeSO4, MnCl2, ZnCl2 and CdCl2. in which of these solutions precipitation will take place?

Q 73 | Page 230

NCERT Chemistry Class 11 Part 1

Chemistry Textbook for Class 11 Part 1
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