The molarity of an aqueous solution of NaOH is 2.0 M and its density is 1.08 g mL ⁻¹ . What is the molality of the solution?

Step-by-step solution

Let the volume of the solution be 1 L ( 1000 mL ). Moles of NaOH in 1 L solution = 2.0 mol Mass of NaOH = 2.0 mol 40 g mol ⁻¹ = 80 g Mass of 1 L solution = Volume Density = 1000 mL 1.08 g mL ⁻¹ = 1080 g Mass of solvent (water) = Mass of solution - Mass of solute Mass of solvent = 1080 g - 80 g = 1000 g = 1 kg Molality ( m ) = Moles of solute Mass of solvent (in kg) = 2.0 mol 1 kg = 2.0 m Answer: 2.0 m