Question

the molarity of NaNO3 solution is 1 m the density of solution is 1.25g /ml calculate molality of solution​

Answer 1

Molarity = 1 mol/L ie 1 mole of NaNO3 in 1000ml solution

mass of NaNO3(solute) = 1 x 85 = 85g

Density of solution = 1.25g/ml

Mass of solution = Volume x Density = 1000 x 1.25 = 1250g

Mass of solvent = Mass of solution - mass of solute = 1250 - 85 = 1165g = 1.165kg

Molality of solution = no. of moles of NaNO3/Mass of solvent in Kg = 1/1.165 = 0.86 mol/Kg