Question

Calculate the molarity of $40\%\left(\frac{w}{W}\right)$ $NaOH$ solution, if density is $d\text{g/mL}$

• A. $2dM$
• B. $4dM$
• C. $6dM$
• D. $10dM$

Answer 1

The correct option is D $10dM$

Given,
$100\text{g}$ solution contains $40\text{g}$ $NaOH$
Molar mass of $NaOH=(23+16+1)\text{g/mol}=40\text{g/mol}$
Volume of the solution $=\frac{100}{d\times 1000}=\frac{1}{10d}\text{L}$
Therefore, $\frac{1}{10d}\text{L}$ solution contains $1$ mol of $NaOH$
Hence, Molarity $=\frac{1}{\frac{1}{10d}}=10dM$