Question

For a weak acid $HA$ , the value of $K_a=10^{-4},$ then calculate the $pH$ of $0.01M$ solution of this acid.

• A. $0.1$
• B. $3$
• C. $0.7$
• D. $1$

Answer 1

Answer: (B)

$H^{+}=\sqrt{K_a\times C}$
$H^{+}=\sqrt{10^{-4}\times 10^{-2}}=10^{-3}mol{L}^{-1}$
$pH=-\log \left[10^{-3}\right]=3$