Question

Assumed $Ca(OH{)}_2$ to be completely ionized the $pH$ of 0.01 M molar aqueous solution of calcium hydroxide is approximately:

• A. 10.5
• B. 11.8
• C. 13.7
• D. 12.3

Answer 1

The correct option is D 12.3

Since $Ca(OH{)}_2$ is a strong base , it will ionize completely.$Ca\left(OH{)}_2\right(aq.\left)\stackrel{+H_{2}O}{⟶}C{a}^{2+}\right(aq.)+2O{H}^{-}(aq.)Initial:C00Equilibrium:0C2C$
$[O{H}^{-}{]}_{eqb}=2\times [Ca(OH{)}_2{]}_{initially}=2\times C=0.02MpOH=-\log [O{H}^{-}]pOH=-\log (0.02)=2-0.3=1.7pH+pOH=14pH=14-1.7=12.3$