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

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    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

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    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

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    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

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

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    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⊕

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

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    2. Answer the following in one sentence :

    i. Why cations are Lewis acids ?

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    ii. Why is KCl solution neutral to litmus?

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    iii. How are basic buffer solutions prepared?

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

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    v. Write one property of a buffer solution.

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

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    vii. Calculate the pH of 0.01 M sulphuric acid.

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

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

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

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    3. Answer the following in brief :

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

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    ii. What is meant by conjugate acidbase pair?

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

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

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

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

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    vii. Derive the relation pH + pOH = 14.

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    viii. Aqueous solution of sodium carbonate is alkaline whereas aqueous solution of ammonium chloride is acidic. Explain.
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    ix. pH of a weak monobasic acid is 3.2 in its 0.02 M solution. Calculate its dissociation constant.

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

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    4. Answer the following :

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

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

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

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

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

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    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.

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

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    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

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

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