0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (K<sub>b</sub> for pyridine is 1.5 x 10<sup>−9</sup>M). pH is:

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246

Physical Chemistry MCQ with Answers

246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (K_b for pyridine is 1.5 x 10⁻⁹M). pH is:

Answer is:

5

Explanation:

pOH = pK_b + log ([salt]⁄[base])

Physical Chemistry MCQ with Answers

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247) M(OH)_x has K_sp = 4 x 10⁻¹² and solubility 10⁻⁴. x is:

Answer is:

2

248) To a mixture of NH₄Cl and NH₃ in water, a further amount of NH₄Cl is added. The pH of the mixture is:

Increase

Decrease

Remain same

Be unpredictable

Answer is:

Decrease

Explanation:

pOH = pK_b + log ([salt]⁄[base])

249) What will be the pH of an aqueous solution of 1M ammonium formate assuming complete dissociation? (pK_a for formic acid = 3.8 and pK_b for ammonia = 4.8)

3.8

4.8

6.5

8.5

Answer is:

6.5

Explanation:

pH = 7 + 0.5pK_a − 0.5pK_b

250) pH of 0.02M solution of pyridinium hydrochloride (a salt of strong acid and weak base) is 3.44. The ionisation constant of pyridine is:

1.51 x 10⁻⁷

1.51 x 10⁻⁸

1.51 x 10⁻⁹

1.51 x 10⁻¹⁰

Answer is:

1.51 x 10⁻⁹

Explanation:

pH = −0.5 [log K_w − log K_b + log C]

Physical Chemistry MCQ with Answers

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246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (Kb for pyridine is 1.5 x 10−9M). pH is:

5

Physical Chemistry MCQ with Answers

Related Physical Chemistry MCQ with Answers

247) M(OH)x has Ksp = 4 x 10−12 and solubility 10−4. x is:

2

248) To a mixture of NH4Cl and NH3 in water, a further amount of NH4Cl is added. The pH of the mixture is:

Decrease

249) What will be the pH of an aqueous solution of 1M ammonium formate assuming complete dissociation? (pKa for formic acid = 3.8 and pKb for ammonia = 4.8)

6.5

250) pH of 0.02M solution of pyridinium hydrochloride (a salt of strong acid and weak base) is 3.44. The ionisation constant of pyridine is:

1.51 x 10−9

Physical Chemistry MCQ with Answers

246) 0.15 mol of pyridinium chloride has added to 500 cc of 0.2M pyridine solution (K_b for pyridine is 1.5 x 10⁻⁹M). pH is:

247) M(OH)_x has K_sp = 4 x 10⁻¹² and solubility 10⁻⁴. x is:

248) To a mixture of NH₄Cl and NH₃ in water, a further amount of NH₄Cl is added. The pH of the mixture is:

249) What will be the pH of an aqueous solution of 1M ammonium formate assuming complete dissociation? (pK_a for formic acid = 3.8 and pK_b for ammonia = 4.8)

1.51 x 10⁻⁹