Suppose that you add 29.2 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f of 5.12 oC/m. With the added solute, you find that there is a freezing point depression of 2.78 oC compared to pure benzene. What is the molar mass (in g/mol) of the unknown compound

Suppose that you add 29.2 g of an unknown molecular compound to 0.250 kg of benzene, which has a K f of 5.12 oC/m. With the added solute, you find that there is a freezing point depression of 2.78 oC compared to pure benzene. What is the molar mass (in g/mol) of the unknown compound

Explanation:

The mass of nonvolatile solute added is ---- 29.2g

The mass of solvent benzene is ---- 0.250kg = 250g

The Kf value of benzene is ---- 5.12^oC/m.

Depression in the freezing point of the solution is --- 2.78^oC.

What is the molar mass of the unknown solute?

Substitute the given values in this formula to get the molar mass of unknown solvent:

Hence, the molar mass of unknown solute is --- 215g/mol.