Chapter 3 Ionic Equilibrium Class 12 Chemistry Textbook Solution

1. Choose the most correct answer :

i. The pH of 10-8 M of HCl is a. 8 b. 7 c. less than 7 d. greater than 7

ii. Which of the following solution will have pH value equal to 1.0 ? a. 50 mL of 0.1M HCl + 50mL of 0.1M NaOH b. 60 mL of 0.1M HCl + 40mL of 0.1M NaOH c. 20 mL of 0.1M HCl + 80mL of 0.1M NaOH d. 75 mL of 0.2M HCl + 25mLof 0.2M NaOH

iii. Which of the following is a buffer solution ? a. CH3COONa + NaCl in water b. CH3COOH + HCl in water c. CH3COOH+CH3COONa in water d. HCl + NH4Cl in water

iv. The solubility product of a sparingly soluble salt AX is 5.2×10-13. Its solubility in mol dm-3 is a. 7.2 × 10-7 b. 1.35 × 10-4 c. 7.2 × 10-8 d. 13.5 × 10-8

v. Blood in human body is highly buffered at pH of a. 7.4 b. 7.0 c. 6.9 d. 8.1

vi. The conjugate base of [Zn(H2O)4]2⊕ is a. [Zn(H2O)4]2 NH3 b. [Zn(H2O)3]2 c. [Zn(H2O)3OH]⊕ d. [Zn(H2O)H]3⊕

vii. For pH > 7 the hydronium ion concentration would be a. 10-7M b. < 10-7M c. > 10-7M d. ≥ 10-7M

2. Answer the following in one sentence :

i. Why cations are Lewis acids ?

ii. Why is KCl solution neutral to litmus?

iii. How are basic buffer solutions prepared?

iv. Dissociation constant of acetic acid is 1.8 × 10-5. Calculate percent dissociation of acetic acid in 0.01 M solution.

v. Write one property of a buffer solution.

vi. The pH of a solution is 6.06. Calculate its H⊕ ion concentration.

vii. Calculate the pH of 0.01 M sulphuric acid.

viii. The dissociation of H2S is suppressed in the presence of HCl. Name the phenomenon.

ix. Why is it necessary to add H2SO4 while preparing the solution of CuSO4?

x. Classify the following buffers into different types : a. CH3COOH + CH3COONa b. NH4OH + NH4Cl c. Sodium benzoate + benzoic acid d. Cu(OH)2 + CuCl2

3. Answer the following in brief :

i. What are acids and bases according to Arrhenius theory ?

ii. What is meant by conjugate acidbase pair?

iii. Label the conjugate acid-base pair in the following reactions a. HCl + H2O H3O⊕ + Cl b. CO3 2 + H2O OH + HCO3

iv. Write a reaction in which water acts as a base.

v. Ammonia serves as a Lewis base whereas AlCl3 is Lewis acid. Explain.

vi. Acetic acid is 5% ionised in its decimolar solution. Calculate the dissociation constant of acid

vii. Derive the relation pH + pOH = 14.

viii. Aqueous solution of sodium carbonate is alkaline whereas aqueous solution of ammonium chloride is acidic. Explain.

ix. pH of a weak monobasic acid is 3.2 in its 0.02 M solution. Calculate its dissociation constant.

x. In NaOH solution [OH ] is 2.87 × 10-4. Calculate the pH of solution.

4. Answer the following :

i. Define degree of dissociation. Derive Ostwald's dilution law for the CH3COOH.

ii. Define pH and pOH. Derive relationship between pH and pOH.

iii. What is meant by hydrolysis ? A solution of CH3COONH4 is neutral. why ?

iv. Dissociation of HCN is suppressed by the addition of HCl. Explain.

vi. Derive the relationship between degree of dissociation and dissociation constant in weak electrolytes.

vii. Sulfides of cation of group II are precipitated in acidic solution (H2S + HCl) whereas sulfides of cations of group IIIB are precipitated in ammoniacal solution of H2S. Comment on the relative values of solubility product of sulfides of these.

viii. Solubility of a sparingly soluble salt get affected in presence of a soluble salt having one common ion. Explain.

ix. The pH of rain water collected in a certain region of Maharashtra on particular day was 5.1. Calculate the H⊕ ion concentration of the rain water and its percent dissociation

x. Explain the relation between ionic product and solubility product to predict whether a precipitate will form when two solutions are mixed?