Question

What is the pH of a solution that contains 0.83M HCN (Ka = 4.9x10-10) and 0.64 M potassium cyanide?

Answer 1

Answer:

pH= 9.2

Explanation:

Henderson hasselbach equation

pKa= log Ka= log (4.9 x 10^-10)=9.3

$pH=Pka+log \frac{[A-]}{[HA]}$

$pH=9.3+log \frac{[CN-]}{[HCN]}$

$pH=9.3+log \frac{[0.64 M]}{[0.83 M]}$

pH= 9.2