Question

What molarity is $10\%$ $\mathrm{NaOH}$?

Answer 1

Molarity(M):

• It can be defined as the number of moles of solute divided by the volume of the solution in liters.
• Hence, the formula can be given as: $\mathrm{M}=\frac{\mathrm{n}}{\mathrm{V}}$ where, $\mathrm{n}$ = number of moles of solute and $\mathrm{V}$= volume of the solution in liters.
• $10\%$ $\mathrm{NaOH}$ means $100\mathrm{ml}$ of solution containing $10\mathrm{g}$ of $\mathrm{NaOH}$.
• Given that, the number of $\mathrm{NaOH}$ solution = $10\%$.

The molar mass of $\mathrm{NaOH}$ = $40\mathrm{g}/\mathrm{mol}.$

Thus, the number of moles $10\%$ $\mathrm{NaOH}$ = $\frac{10}{40}$=$\frac{1}{4}$= $0.25\mathrm{moles}$

Volume of $10\%$ $\mathrm{NaOH}$ solution = $\frac{100}{1000}$ = $0.1\mathrm{L}$.

Molarity(M) = $\frac{0.25}{0.1}$= $2.5\mathrm{M}$.

Hence, the Molarity(M) of $10\%$ $\mathrm{NaOH}$ = $2.5\mathrm{M}$.