Classes at: - Topic: Ionic Equilibrium

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1 01. Hydrogen ion concentration in mol/l in a solution of ph = 5.4 will be : [AIEEE 2005] (a) (b) (c) (d) If the dissociation constant of an acid HA is , the ph of a 0.1 M solution of the acid HA will be approximately : [MPCET 1999] (a) 3 (b) 5 (c) 1 (d) The ph of a solution is 5.0. To this solution sufficient acid is added to decrease the ph to 2.0. The increase in hydrogen ion concentration is:[pmt (MP) 90; CPMT 90] (a) 1000 times (b) 5/2 times (c) 100 times (d) 5 times 04. When the ph of a solution is 2 the hydrogen ion concentration is : [NCERT 1993] (a) M (b) M (c) M (d) M 05. The ph of 1/1000 N KOH solution is: [MLNR 1991; CET (Karnataka) 1992] (a) (b) 3 (c) 2 (d) At 90 C, pure water has [H 3 O + ] = 10 6 mol/ litre. The value of K w at 90 C is : [MLNR 1990; CBSE (PMT) 1993] (a) 10 6 (b) (c) (d) ph of a 10 8 M solution of HCl in water is: [MLNR 1990] (a) 8 (b) 8 (c) between 7 and 8 (d) between 6 and 7 PHYSICAL CHEMISTRY by: SHAILENDRA KR. Classes at: - SCIENCE TUTORIALS; Opp. Khuda Baksh Library, Ashok Rajpath, Patna PIN POINT STUDY CIRCLE; House No. 5A/65, Opp. Mahual Kothi, Alpana Market, Patna Topic: Ionic Equilibrium Meq. Approach 08. The ph of the solution is 4. The hydrogen ion concentration of the solution in mol/litre is : [CPMT 1991] (a) 10 2 (b) 10 4 (c) 10 4 (d) The ph of 0.1 N HCl solution is: (a) 1.0 (b) 7.0 (c) 14.0 (d) molar solution of formic acid is 3.2% ionized. Its ionization constant is: (a) (b) (c) (d) pk a values of four acids are given below at 25 C. The strongest acid is: [PMT (MP) 90] (a) 2.0 (b) 2.5 (c) 3.0 (d) The values of dissociation constant of some acids (at 25 C) are given below. The strongest acid in water is : (a) (b) (c) (d) The concentration of hydrogen ion [H + ] and ph in 10 M HCl is : [CBSE (PMT) 1995] (a) 10 1, zero (b) 10 1, 1 (c) 10 2, 1 (d) 10 1, The ph of solution, whose hydrogen ion concentration is one mol per litre, will be: (a) 1.0 (b) 0.1 (c) zero (d) 1.5 Page No.: 1

2 15. The ph of 0.1 M HCl is approximately 1. The approximate ph of 0.05 M H 2 SO 4 is : (a) 0.05 (b) 0.5 (c) 1 (d) The ph of a 0.01 M solution of acetic acid having degree of dissociation 12.5% is: (a) (b) (c) (d) The ph of water is 7 at 25 C. If water is heated to 50 C, which of the following should be true? (a) ph will decrease (b) ph will increase (c) ph will remain seven (d) [H + ] will increase but [OH ] will decrease 18. The [H 3 O + ] in the rain water of ph = 4.35 is: (a) M (b) M (c) M (d) M 19. The [OH ] in 100 ml of M HCl (aq.) is : (a) M (b) M (c) M (d) M 20. Which solution will have ph closer to 1.0? [IIT 1992] (a) 100 ml of (M/10) HCl ml of (M/10) NaOH (b) 55 ml of (M/10) HCl + 45 ml of (M/10) NaOH (c) 10 ml of (M/10) HCl + 90 ml of (M/10) NaOH (d) 75 ml of (M/5) HCl + 25 ml of (M/5) NaOH 21. Which of the following will occur if a 0.1 M solution of a weak acid is diluted to 0.01 M at constant temperature? [ MLNR 1992; AIIMS 1993] (a) [H + ] will decrease to 0.01 M (b) ph will decrease (c) percentage ionization will increase (d) K a will increase 22. A certain buffer solution contains equal concentration of X and HX. The K a for HX is The ph of the buffer is : [MLNR 1992] (a) 3 (b) 8 (c) 11 (d) The ph of a M NaOH solution is nearest to : [MLNR 1992] (a) 10 (b) 7 (c) 4 (d) The ph of a 0.02 M solution of hydrochloric acid is : [PMT (MP) 1993] (a) 2.0 (b) 1.7 (c) 0.3 (d) ph of 0.05 M Mg(OH) 2 is: [CBSE (PMT) 90] (a) 13 (b) 10 (c) 1 (d) zero 26. K a for HCN is at 25 C. For maintaining a constant ph of 9, the volume of 5 M KCN solution required to be added to 10 ml of 2 M HCN solution is: [CBSE (PMT) 93] (a) 4 ml (b) 7.95 ml (c) 2 ml (d) 9.3 ml 27. An aqueous solution of 0.1 M NH 4 Cl will have a ph closer to : [ AIIMS 1993] (a) 9.1 (b) 8.1 (c) 7.1 (d) The number of mole of hydroxide [OH ] ion in 0.3 litre of M solution of Ba(OH) 2 is : [CPMT 1991] (a) (b) (c) (d) A 0.01 M ammonia solution is 5% ionized. The concentration of [OH ] ion is : [CET (Karnataka) 1993] (a) M (b) M (c) M (d) 0.05 M g of pure NaOH is dissolved in 10 litre of distilled water. The ph of the solution is : [CET (Karnataka) 1991] (a) 9 (b) 10 (c) 11 (d) 12 Page No.: 2

3 31. The ph of the solution produced when an aqueous solution of strong acid ph 5 is mixed with equal volume of an aqueous solution of strong acid of ph 3 is:[cet (Karnataka) 91] (a) 3.3 (b) 3.5 (c) 4.5 (d) An acid-base indicator has K a = The acid form of the indicator is red and the basic form is blue. the [H + ] required to change the indicator from 75% red to 75% blue is : [CET (Karnataka) 1993] (a) M (b) M (c) M (d) M 33. A certain weak acid has a dissociation constant The equilibrium constant for its reaction with a strong base is : [IIT 1994] (a) (b) (c) (d) If K a for a weak acid is pk b value of its conjugate base is : [NTSE 1991] (a) 5 (b) 6 (c) 7 (d) A solution of ph 9.0 is one thousand times as basic as a solution of ph :[EAMCET 1990] (a) 6 (b) 7 (c) 4 (d) In 100 ml of an aqueous HCl of ph 1.0, 900 ml of distilled water is added, the ph of the resultant solution becomes : [EAMCET 92] (a) 1.0 (b) 2.0 (c) 4.0 (d) The ph of a soft drink is Its H + ion concentration will be : [PMT (MP) 1990] (a) mol/litre (b) mol/litre (c) mol/litre (d) mol/litre 38. The heat of neutralization ( H) of a strong acid and strong base in dilute aqueous solutions at 25 C is : [BHU 1992,93] (a) kj (b) kj (c) kj (d) kj 39. The dissociation constant of HCN is The value of hydrolysis constant of KCN will be : [BHU 1992] (a) (b) (c) (d) If the solubility of lithium sodium hexafluoroaluminate, Li 3 Na 3 (AlF 6 ) 2 is a mol/litre, its solubility product is equal to : [CPMT 92] (a) a 2 (b) 12a 2 (c) 18a 3 (d) 2916a The solubility of AgCl in water at 10 C is mol/litre. The K sp of AgCl is : [BHU 1992] (a) [ ] 1/2 (b) 6.2 (10 6 ) 2 (c) (6.2) (d) [ ] K sp of AgCl at 18 C is If Ag + of solution is mol/litre the Cl that must exceed before AgCl is precipitated would be: [CPMT 1991] (a) mol/litre (b) mol/litre (c) mol/litre (d) mol/litre 43. In which of the following solutions the solubility of AgCl will be maximum? [CBSE (PMT) 1993] (a) 0.1 M AgNO 3 (b) Water (c) 0.1 M NaCl (d) 0.1 M KCl 44. The solubility of PbCl 2 in water is 0.01 M at 25 C. Its maximum concentration in 0.1 M NaCl will be : [CBSE (PMT) 1993] (a) M (b) M (c) M (d) M 45. If the solubility product of lead iodide (PbI 2 ) is , its solubility will be : [PMT (MP)90] (a) M (b) M (c) M (d) M 46. The solubility product of a salt AB 2 is at 373 K. The solubility of AB 2 in boiling water will be : [Roorkee 1990] (a) M (b) M (c) M (d) M Page No.: 3

4 47. The solubility of AgCl is g/litre. The solubility product of AgCl will be : (a) (b) (c) (d) Under the same conditions which mixture by volume of 1 M potassium hydroxide and 1 M nitric acid solution produces the highest temperature? [PMT (MP) 1990] (a) (b) (c) (d) If the concentration of CrO 4 ion in a saturated solution of silver chromate be M, solubility product of silver chromate will be : [CPMT 1993] (a) (b) (c) (d) At 30 C the solubility of Ag 2 CO 3 (K sp = ) would be greatest in one litre of [PMT (MP) 1990] (a) 0.05 M Na 2 CO 3 (b) 0.05 M AgNO 3 (c) pure water (d) 0.05 M K 2 CO Heat of neutralization for the reaction NaOH + HCl NaCl + H 2 O is 57.1 kj mol 1. What will be the heat released when 0.25 mole of NaOH is titrated against 0.25 mole of HCl? [CPMT 1990] (a) 22.5 kj (b) 57.1 kj (c) 14.3 kj (d) 28.6 kj 52. The solubility of AgCl (K sp = ) in a 0.10 M NaCl solution is : [PMT (MP) 1992; Roorkee 1995] (a) 0.1 M (b) M (c) M (d) M 53. Solubility product of MX 2 at 298 K is At this temperature concentration of M 2+ ion in mol per litre is : [AIEEE 2005] (a) M (b) M (c) M (d) M 54. The precipitate of CaF 2 (K sp = ) is obtained when equal volumes of the following are mixed : [PMT (MP) 1990; MLNR 1992] (a) 10 4 M Ca M F (b) 10 2 M Ca M F (c) 10 5 M Ca M F (d) 10 3 M Ca M F 55. How many gram of CaC 2 O 4 will dissolve in one litre of saturated solution? K sp of CaC 2 O 4 is mol 2 and its molecular weight is 128 : [PMT (MP) 1993] (a) g (b) g (c) g (d) g 56. The ph of a M NaOH solution is nearest to : [MLNR 1992] (a) 10 (b) 7 (c) 4 (d) A physician wishes to prepare a buffer solution at ph = 3.58 that efficiently resists a change in ph yet contains only small conc. of the buffering agents. Which one of the following weak acid together with its sodium salt would be best to use?[cbse (PMT) 97] (a) m-chloro bezoic acid (pk a = 3.98) (b) p-chlorocinnamic acid (pk a = 4.41) (c) 2, 5-dihydroxy benzoic acid (pk a = 2.97) (d) Acetoacetic acid (pk a = 3.58) 58. K b for the hydrolysis reaction, B + + H 2 O BOH + H + is , the hydrolysis constant of the salt is : [Roorkee 1998] (a) 10 6 (b) 10 7 (c) 10 8 (d) The hydroxide with highest solubility product is : [Roorkee 1994] (a) Al(OH) 3 (b) CO(OH) 2 (c) Cr(OH) 3 (d) Fe(OH) The dissociation constant of NH 4 OH is The hydrolysis constant of NH 4 Cl would be : [Roorkee 1993] (a) (b) (c) (d) The ph of 1.0 M aqueous solution of a weak acid HA is 6.0. Its dissociation constant is : [Roorkee 1993] (a) 10 6 (b) (c) 1.0 (d) 6.0 Page No.: 4

5 62. A weak acid HX (K a = ) on reaction with NaOH gives NaX. For 0.1 M aqueous solution of NaX, the % hydrolysis is : [IIT 2004] (a) 0.001% (b) 0.01% (c) 0.15% (d) 1% 63. In a mixture of CH 3 COOH and CH 3 COONa, the ratio of salt to acid concentration is increased by ten folds. The ph of the solution will increase by: [Roorkee 1991] (a) Zero (b) 1 (c) 2 (d) If pk b for fluoride ion at 25 C is 10.83, the ionization constant of hydrofluoric acid in water at this temperature is: [IIT 1997] (a) (b) (c) (d) The solubility of a saturated solution of calcium fluoride is moles per litre. Its solubility product is: [CBSE (PMT) 1999] (a) (b) (c) (d) At infinite dilution, the percentage ionisation for both strong and weak electrolytes is : [CPMT 1999] (a) 1% (b) 20% (c) 50% (d) 100% 67. A buffer solution is prepared by mixing 10 ml of 1.0 M acetic and 20 ml of 0.5 M sodium acetate and then diluted to 100 ml with distilled water. If the pk a of CH 3 COOH is 4.76, what is the ph of the buffer solution prepared? [MPCET 1999] (a) 5.21 (b) 4.76 (c) 4.34 (d) To neutralise completely 20 ml of 0.1 M aqueous solution of phosphorous acid H 3 PO 3, the volume of 0.1 M KOH solution required is : [AIEEE 2004] (a) 60 ml (b) 20 ml (c) 40 ml (d) 10 ml 69. What is the correct representation for the solubility product of SnS 2? [MPCET 1999] (a) [Sn 2+ ] [S 2 ] 2 (b) [Sn 4+ ] [S 2 ] 2 (c) [Sn 2+ ] [2S 2 ] (d) [Sn 4+ ] [2S 2 ] The concentration of [H + ] and concentration of [OH ] of a 0.1 M aqueous solution of 2% ionised weak acid is [ionic product of water = ] : [CBSE (PMT) 1999] (a) M and M (b) M and M (c) M and M (d) M and M 71. The solubility product of a sparingly soluble salt AX 2 is Its solubility (in mol/ litre) is : [CBSE (PMT) 2004] (a) (b) (c) (d) The solubility in water off a sparingly soluble salt AB 2 is mol/litre. Its solubility product is : [AIEEE 2003] (a) (b) (c) (d) Solubility of an aqueous solution of Mg(OH) 2 is X mole litre 1, then its K sp is: [AIEEE 2002] (a) 4X 3 (b) 108X 5 (c) 27X 4 (d) 9X mole of CH 3 NH 2 (K b = ) is mixed with 0.08 mole of HCl and diluted to 1 litre. The [H + ] in solution is: [IIT 2005] (a) M (b) M (c) M (d) M 75. AT 25 C, K b for a base BOH is The [OH ] in 0.01 M aqueous solution of base is : [CBSE (PMT) 2005] (a) (b) (c) (d) The hydrogen ion concentration of a 10 8 M HCl aqueous solution at 298 K (K w = ) is : [CBSE (PMT) 2006] (a) M (b) M (c) M (d) M Page No.: 5

6 A N S W E R 01. d 02. a 03. a 04. b 05. d 06. b 07. d 08. c 09. a 10. b 11. a 12. a 13. a 14. c 15. c 16. c 17. a 18. a 19. c 20. d 21. c 22. b 23. b 24. b 25. a 26. c 27. d 28. c 29. c 30. b 31. a 32. c 33. c 34. d 35. a 36. b 37. c 38. b 39. d 40. d 41. d 42. a 43. b 44. d 45. a 46. d 47. b 48. c 49. c 50. c 51. c 52. c 53. b 54. b 55. a 56. b 57. d 58. c 59. b 60. d 61. b 62. b 63. b 64. c 65. d 66. d 67. b 68. c 69. b 70. c 71. c 72. c 73. a 74. b 75. a 76. d Page No.: 6