Calculate the molarity of \(\mathrm{NaOH}\) solution prepared by dissolving \(0.4 \mathrm{~g}\) of…
Calculate the molarity of \(\mathrm{NaOH}\) solution prepared by dissolving \(0.4 \mathrm{~g}\) of \(\mathrm{NaOH}\) in enough water to form \(500 \mathrm{~mL}\) of the solution.
0.02
0.05
0.04
0.03
Solution
Molarity \(=\frac{w_B \mathrm{gL}^{-1}}{M_B \mathrm{~g} \mathrm{~mol}^{-1}}=\frac{\frac{0.4}{500} \times 100}{40}=0.02 \mathrm{M}\) \(\left[\therefore w_B=\right.\) mass of solute \((\mathrm{NaOH})=0.4 \mathrm{~g} / \mathrm{mL}\) \(M_B=\) molar mass of \(\mathrm{NaOH}=40 \mathrm{~g} \mathrm{~mol}^{-1} 1\)