Question

In which of the following cases, pH is greater than $7$?

• A. $50ml$ of $0.01M$ $HCl+50ml$ of $0.1M$ $NaCl$
• B. $50ml$ of $0.1M$ $H_2{SO}_4+50ml$ of $0.2M$ $NaOH$
• C. $50ml$ of $0.1M$ ${CH}_{3}COOH+50ml$ of $0.1M$ $KOH$
• D. $50ml$ of $0.1M$ $H{NO}_3+50ml$ of $0.1M$ ${NH}_3$

Answer 1

The correct option is C $50ml$ of $0.1M$ ${CH}_{3}COOH+50ml$ of $0.1M$ $KOH$

$\left(a\right)\left[H_3{O}^{+}\right]=\frac{0.1}{2}=0.05$; $pH=-\log 0.05=1.301$

$\left(b\right)$ Complete neutralization of strong acid and strong base, $pH=7$

$\left(c\right)$ Hydrolysis of the salt ${CH}_{3}COOK$, $pH>7$ (salt of weak acid with strong base)

$\left(d\right)$ Hydrolysis of the salt ${NH}_4{NO}_3$, $pH<7$ (salt of strong acid with weak base)