Question

A solution containing 10.976 g of lauric acid and 1.248 g of the unknown. From the measured freezing points, they determined their molality of this solution to be 0.531m. Calculate the number of moles of unknown in the solution.

Answer 1

Molality of a solution =( no.of moles of solute/mass of solvent in kg) .

Given molality of the solution = 0.531m

Mass of the solvent = 10.976g= 0.010976kg

Since solute is the component in the solution which is less in quantity.

Solvent is the component of the solution which is more in quantity.

Hence lauric acid is the solvent.

The unknown compound is the solute.

By substituting in the molality formula,we get the no.of moles of the unknown compound.

n=0.531m. 0.010976kg

= 0.0058

Hence the unknown compound is 0.0058 moles in the solution.

answered by: anonymous