Question

Calculate the molarity of KOH in a solution prepared by dissolving 5.6 gm in enough water to form 500 mL of solution.

• A. 2 M
• B. 0.2 M
• C. 5.6 M
• D. 500 M

Answer 1

The correct option is B

0.2 M

Molar mass of solute (KOH) = (39 + 16 + 1) gm = 56 gm
$\therefore$ Number of moles = $\frac{\text{Given weight}}{\text{Molecular mass}}=\frac{5.6}{56}=0.1$

Also, molarity = $\frac{\text{Number of moles}}{\text{Volume of solution (litre)}}=\frac{0.1}{500\times {10}^{-3}}$
Molarity = 0.2 M