A current of $0.250 \mathrm{~A}$ is passed through $400 \mathrm{~ml}$ of a $2.0 \mathrm{~M}$ solution of $\mathrm{NaCl}$ for $35 \mathrm{minutes}$. What will be the $\mathrm{pH}$ of the solution after the current is turned off ?

Question

Aicharya · Accepted Answer

After electrolysis, aqueous $\mathrm{NaCl}$ is converted into aqueous $\mathrm{NaOH}$.
The quantity of electricity passed $=\frac{0.250 \times 35 \times 60}{96500} \mathrm{~F}=5.44 \times 10^{-3} \mathrm{~F}$
The number of equivalents of $\mathrm{OH}^{-}$ion formed $=5.44 \times 10^{-3}$
$\therefore$ Morality of $\mathrm{NaOH}=$
$\frac{5.44 \times 10^{-3}}{0.4 \mathrm{~L}}=1.36 \times 10^{-2}$
$\therefore \mathrm{pOH}=-\log \left(1.36 \times 10^{-2}ight)=1.87$
$\therefore \mathrm{pH}=12.13$

A current of $0.250 \mathrm{~A}$ is passed through $400 \mathrm{~ml}$ of a $2.0 \mathrm{~M}$ solution of…

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