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Question: The pH of 0.5 (M) Ba(CN)<sub>2</sub> solution is- Given pK<sub>b</sub> of CN<sup>–</sup> = 9.3...

The pH of 0.5 (M) Ba(CN)2 solution is-

Given pKb of CN = 9.3

A

8.35

B

3.35

C

9.35

D

9.5

Answer

9.35

Explanation

Solution

Ba2+ is not hydrolysed , CN = 1 (M)

CN + H2O \rightleftarrowsHCN + OH

pH = 12\frac{1}{2} (pKw + pKa + log c)

pH = 12\frac{1}{2} (pKw + pKa) since c = 1(M)

pH = 12\frac{1}{2} (2pKw – pKb) = 12\frac{1}{2} (28 – 9.3)

pH = 12\frac{1}{2} (28 – 9.3) = 9.35