AIPMT PRELIMS2011Chemistry-Equilibrium

AIPMT PRELIMS 2011 Chemistry Buffer Solutions MCQ Question

Type: MCQ-numerical-Hard-Class 11

A buffer solution is prepared in which the concentration of NH₃ is 0.30 M and the concentration of NH₄⁺ is 0.20 M. If the equilibrium constant, Kb for NH₃ equals 1.8 × 10⁻⁵, what is the pH of this solution?

A

8.73

B

9.08

C

9.43

D

11.72

Correct Answer

Option C

Detailed Explanation

pOH = pKb + log([Salt]/[Base]) = 4.74 - 0.176 = 4.56. Therefore, pH = 14 - 4.56 = 9.44.

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