Question

What is the molality of a semimolar NaCl solution if the density of the solution is 1.16cm^(-3)

Answer 1

Answer:

Seminormal NaCl solution means 0.5 M solution and density of solution is 1.16 g /cc.

Mass of one litre of solution = 1000 x 1.16 = 1160 g

Mass of solute in one litre of solution = 58.5 x 0.5 = 29.25 g

Mass of solvent = 1160 -29.25 =1130.75 g = 1.13075 kg

Molality = 0.5 mole/ mass of solvent in Kg

= 0.5 / 1.13075 = 0.442 m

PS: In reality , density of 0.5 m solution will be lower than 1.13 g / cc