Chemistry · Textbook solutions

Ionic Equilibria

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 49 questions

3. Ionic Equilibria — worked examples

13 q

Solved Examples

Worked · 13
  1. Solved Ex.3.1
    A weak monobasic acid is 0.05% dissociated in 0.02 M solution. Calculate dissociation constant of the acid.
  2. Solved Ex.3.2
    The dissociation constant of NH4OH\mathrm{NH_4OH} is 1.8×10−51.8 \times 10^{-5}. Calculate its degree of dissociation in 0.01 M solution.
  3. Solved Ex.3.3
    A weak monobasic acid is 12% dissociated in 0.05 M solution. What is percent dissociation in 0.15 M solution.
  4. Solved Ex.3.4
    Calculate [H3O⊕][\mathrm{H_3O^{\oplus}}] in 0.1 mol dm3\mathrm{dm^3} solution of acetic acid. Given : KaK_a [CH3COOH\mathrm{CH_3COOH}] =1.8×10−5= 1.8 \times 10^{-5}
  5. Solved Ex.3.5
    Calculate pH and pOH of 0.01 M HCl\mathrm{HCl} solution.
  6. Solved Ex.3.6
    pH of a solution is 3.12. Calculate the concentration of H3O⊕\mathrm{H_3O^{\oplus}} ion.
  7. Solved Ex.3.7
    A weak monobasic acid is 0.04 % dissociated in 0.025M solution. What is pH of the solution ?
  8. Solved Ex.3.8
    The pH of monoacidic weak base is 11.2. Calculate its percent dissociation in 0.02 M solution.
  9. Solved Ex.3.9
    Calculate the pH of buffer solution containing 0.05 mol NaF\mathrm{NaF} per litre and 0.015 mol HF\mathrm{HF} per litre. [Ka=7.2×10−4K_a = 7.2 \times 10^{-4} for HF\mathrm{HF}]
  10. Solved Ex.3.10
    Calculate the pH of buffer solution composed of 0.1 M weak base BOH\mathrm{BOH} and 0.2 M of its salt BA\mathrm{BA}. [Kb=1.8×10−5K_b = 1.8 \times 10^{-5} for the weak base]
  11. Solved Ex.3.11
    A solution is prepared by mixing equal volumes of 0.1M MgCl2\mathrm{MgCl_2} and 0.3M Na2C2O4\mathrm{Na_2C_2O_4} at 293 K. Would MgC2O4\mathrm{MgC_2O_4} precipitate out ? KspK_{sp} of MgC2O4\mathrm{MgC_2O_4} at 293 K is 8.56×10−58.56 \times 10^{-5}.
  12. Solved Ex.3.12
    The solubility product of AgBr\mathrm{AgBr} is 5.2×10−135.2 \times 10^{-13}. Calculate its solubility in mol dm−3\mathrm{mol\ dm^{-3}} and g dm−3\mathrm{g\ dm^{-3}} (Molar mass of AgBr\mathrm{AgBr} = 187.8 g mol−1\mathrm{g\ mol^{-1}})
  13. Solved Ex.3.13
    If 20.0 cm3\mathrm{cm^3} of 0.050 M Ba(NO3)2\mathrm{Ba(NO_3)_2} are mixed with 20.0 cm3\mathrm{cm^3} of 0.020 M NaF\mathrm{NaF}, will BaF2\mathrm{BaF_2} precipitate ? KspK_{sp} of BaF2\mathrm{BaF_2} is 1.7×10−61.7 \times 10^{-6} at 298 K.

Exercises

36 q

1. Choose the most correct answer

Practice · 7
  1. Choose the most correct answer :
    Ex Q.1 (i)
    The pH of 10−810^{-8} M of HCl\mathrm{HCl} is
    1. A.
      8
    2. B.
      7
    3. C.
      less than 7
    4. D.
      greater than 7
  2. Ex Q.1 (ii)
    Which of the following solution will have pH value equal to 1.0 ?
    1. A.
      50 mL of 0.1M HCl\mathrm{HCl} + 50mL of 0.1M NaOH\mathrm{NaOH}
    2. B.
      60 mL of 0.1M HCl\mathrm{HCl} + 40mL of 0.1M NaOH\mathrm{NaOH}
    3. C.
      20 mL of 0.1M HCl\mathrm{HCl} + 80mL of 0.1M NaOH\mathrm{NaOH}
    4. D.
      75 mL of 0.2M HCl\mathrm{HCl} + 25mL of 0.2M NaOH\mathrm{NaOH}
  3. Ex Q.1 (iii)
    Which of the following is a buffer solution ?
    1. A.
      CH3COONa+NaCl\mathrm{CH_3COONa} + \mathrm{NaCl} in water
    2. B.
      CH3COOH+HCl\mathrm{CH_3COOH} + \mathrm{HCl} in water
    3. C.
      CH3COOH+CH3COONa\mathrm{CH_3COOH} + \mathrm{CH_3COONa} in water
    4. D.
      HCl+NH4Cl\mathrm{HCl} + \mathrm{NH_4Cl} in water
  4. Ex Q.1 (iv)
    The solubility product of a sparingly soluble salt AX is 5.2×10−135.2 \times 10^{-13}. Its solubility in mol dm−3\mathrm{mol\ dm^{-3}} is
    1. A.
      7.2×10−77.2 \times 10^{-7}
    2. B.
      1.35×10−41.35 \times 10^{-4}
    3. C.
      7.2×10−87.2 \times 10^{-8}
    4. D.
      13.5×10−813.5 \times 10^{-8}
  5. Ex Q.1 (v)
    Blood in human body is highly buffered at pH of
    1. A.
      7.4
    2. B.
      7.0
    3. C.
      6.9
    4. D.
      8.1
  6. Ex Q.1 (vi)
    The conjugate base of [Zn(H2O)4]2⊕[\mathrm{Zn(H_2O)_4}]^{2\oplus} is
    1. A.
      [Zn(H2O)4]2⊖NH3[\mathrm{Zn(H_2O)_4}]^{2\ominus}\mathrm{NH_3}
    2. B.
      [Zn(H2O)3]2⊖[\mathrm{Zn(H_2O)_3}]^{2\ominus}
    3. C.
      [Zn(H2O)3OH]⊕[\mathrm{Zn(H_2O)_3OH}]^{\oplus}
    4. D.
      [Zn(H2O)H]3⊕[\mathrm{Zn(H_2O)H}]^{3\oplus}
  7. Ex Q.1 (vii)
    For pH >7> 7 the hydronium ion concentration would be
    1. A.
      10−710^{-7}M
    2. B.
      <10−7< 10^{-7}M
    3. C.
      >10−7> 10^{-7}M
    4. D.
      ≥10−7\geq 10^{-7}M

2. Answer the following in one sentence

Practice · 10
  1. Answer the following in one sentence :
    Ex Q.2 (i)
    Why cations are Lewis acids ?
  2. Ex Q.2 (ii)
    Why is KCl\mathrm{KCl} solution neutral to litmus?
  3. Ex Q.2 (iii)
    How are basic buffer solutions prepared?
  4. Ex Q.2 (iv)
    Dissociation constant of acetic acid is 1.8×10−51.8 \times 10^{-5}. Calculate percent dissociation of acetic acid in 0.01 M solution.
  5. Ex Q.2 (v)
    Write one property of a buffer solution.
  6. Ex Q.2 (vi)
    The pH of a solution is 6.06. Calculate its H⊕\mathrm{H^{\oplus}} ion concentration.
  7. Ex Q.2 (vii)
    Calculate the pH of 0.01 M sulphuric acid.
  8. Ex Q.2 (viii)
    The dissociation of H2S\mathrm{H_2S} is suppressed in the presence of HCl\mathrm{HCl}. Name the phenomenon.
  9. Ex Q.2 (ix)
    Why is it necessary to add H2SO4\mathrm{H_2SO_4} while preparing the solution of CuSO4\mathrm{CuSO_4}?
  10. Ex Q.2 (x)
    Classify the following buffers into different types : a. CH3COOH+CH3COONa\mathrm{CH_3COOH} + \mathrm{CH_3COONa} b. NH4OH+NH4Cl\mathrm{NH_4OH} + \mathrm{NH_4Cl} c. Sodium benzoate + benzoic acid d. Cu(OH)2+CuCl2\mathrm{Cu(OH)_2} + \mathrm{CuCl_2}

3. Answer the following in brief

Practice · 10
  1. Answer the following in brief :
    Ex Q.3 (i)
    What are acids and bases according to Arrhenius theory ?
  2. Ex Q.3 (ii)
    What is meant by conjugate acid-base pair?
  3. Ex Q.3 (iii)
    Label the conjugate acid-base pair in the following reactions a. HCl+H2O⇌H3O⊕+Cl⊖\mathrm{HCl} + \mathrm{H_2O} \rightleftharpoons \mathrm{H_3O^{\oplus}} + \mathrm{Cl^{\ominus}} b. CO32⊖+H2O⇌OH⊖+HCO3⊖\mathrm{CO_3^{2\ominus}} + \mathrm{H_2O} \rightleftharpoons \mathrm{OH^{\ominus}} + \mathrm{HCO_3^{\ominus}}
  4. Ex Q.3 (iv)
    Write a reaction in which water acts as a base.
  5. Ex Q.3 (v)
    Ammonia serves as a Lewis base whereas AlCl3\mathrm{AlCl_3} is Lewis acid. Explain.
  6. Ex Q.3 (vi)
    Acetic acid is 5% ionised in its decimolar solution. Calculate the dissociation constant of acid
  7. Ex Q.3 (vii)
    Derive the relation pH + pOH = 14.
  8. Ex Q.3 (viii)
    Aqueous solution of sodium carbonate is alkaline whereas aqueous solution of ammonium chloride is acidic. Explain.
  9. Ex Q.3 (ix)
    pH of a weak monobasic acid is 3.2 in its 0.02 M solution. Calculate its dissociation constant.
  10. Ex Q.3 (x)
    In NaOH\mathrm{NaOH} solution [OH⊖][\mathrm{OH^{\ominus}}] is 2.87×10−42.87 \times 10^{-4}. Calculate the pH of solution.

4. Answer the following

Practice · 9
  1. Answer the following :
    Ex Q.4 (i)
    Define degree of dissociation. Derive Ostwald's dilution law for the CH3COOH\mathrm{CH_3COOH}.
  2. Ex Q.4 (ii)
    Define pH and pOH. Derive relationship between pH and pOH.
  3. Ex Q.4 (iii)
    What is meant by hydrolysis ? A solution of CH3COONH4\mathrm{CH_3COONH_4} is neutral. why ?
  4. Ex Q.4 (iv)
    Dissociation of HCN\mathrm{HCN} is suppressed by the addition of HCl\mathrm{HCl}. Explain.
  5. Ex Q.4 (vi)
    Derive the relationship between degree of dissociation and dissociation constant in weak electrolytes.
  6. Ex Q.4 (vii)
    Sulfides of cation of group II are precipitated in acidic solution (H2S\mathrm{H_2S} + HCl\mathrm{HCl}) whereas sulfides of cations of group IIIB are precipitated in ammoniacal solution of H2S\mathrm{H_2S}. Comment on the relative values of solubility product of sulfides of these.
  7. Ex Q.4 (viii)
    Solubility of a sparingly soluble salt get affected in presence of a soluble salt having one common ion. Explain.
  8. Ex Q.4 (ix)
    The pH of rain water collected in a certain region of Maharashtra on particular day was 5.1. Calculate the H⊕\mathrm{H^{\oplus}} ion concentration of the rain water and its percent dissociation.
  9. Ex Q.4 (x)
    Explain the relation between ionic product and solubility product to predict whether a precipitate will form when two solutions are mixed?