The density of 3 molal solution of NaOH is 1.110 g mL−1. Calculate the molarity of the solution.
3 molal solutoin of NaOH means 3 moles of NaOH are dissolved in 1 kg solvent. So, the mass of solution = 1000 g solvent + 120. g NaOH = 1120 g solution
(Molar mass of NaOH = 23 + 16 + 1 = 40 g and 3 moles of NaOH =3×40=120g)
Volume of solution =Mass of solutionDensity of solution (∵d=mV)
V=1120 g1.110 g mL−1=1009 mL
Molarity=Moles of solute×1000Volume of solution(mL)
=3×10001009=2.973 M≈3M