Question

The ${}_p{K}_{a}HN{O}_2$ is $3.37$. What is the $pH$ of $0.01$ mole/litre aqueous solution of $HN{O}_2$ ?

• A. 2.69
• B. 8.67
• C. 1.69
• D. 3.57

Answer 1

Answer: (B)

We know that for weak acid.
$pH={}_p{K}_w-{}_p{K}_a+\log C$
$\because {}_p{K}_w=14$
${}_p{K}_a=3.37$
$C=0.01$ mole/litre
$pH=14-3.37+\log 0.01$
$pH=14-3.37-2$
$pH=8.67$