Question

Given sodium Hydroxide $\left(NaOH\right)$ is a strong base. Calculate the pH of $0.02M$ $NaOH$ solution.

• A. 10.5
• B. 8.5
• C. 9.3
• D. 12.3

Answer 1

The correct option is D 12.3

Since sodium hydroxide is a strong base, it will dissociate completely in an aqueous solution. $(\alpha =1)$.
This means that the concentration of the base will be equal to the concentration of hydroxide ions after the reaction runs to completion$\left[NaOH\right]=\left[O{H}^{-}\right]$
$NaOH(aq.)\stackrel{+H_{2}O}{\rightleftharpoons }N{a}^{+}(aq.)+O{H}^{-}(aq.)Initial:C00Equilibrium:0CC$
$\left[O{H}^{-}\right]=\left[NaOH\right]=C=0.02MpOH=-log\left[O{H}^{-}\right]pOH=-log\left(0.02\right)=-(0.3-2)=1.7pOH+pH=14pH=14-1.7pH=12.3$