Calculate the molarity of a solution containing 5g of NaOH in 450 mL solution.
Answer & explanation
Correct answer: option 2
Given,
Mass of NaOH = 5g
Volume of the solution = \(450 mL\) =\(450 × 10^{-3}L\)
Molar mass of NaOH = \(23 + 16 + 1 = 40 \text{ g mol}^{-1}\)
Moles of NaOH = \(\frac{\text{mass of NaOH}}{\text{molar mass of NaOH}}\)
moles of NaOH = \(\frac{5 \text{g}}{40} { g mol}^{-1} = 0.125 mol\)
Molarity of the solution =\(\frac{\text{Moles of solute}}{\text{Volume of solution (L)}}\)
Molarity of the solution =\{\frac{0.125 mol}{450 × 10^{-3}}\} = \(0.278 \text{ mol L}^{-1}\) or \(0.278 M\)