# Molecular Weight by Freezing Point Depression

For unknown sample #1, there is 2 g of the unknown sample and 10 mL of water. The freezing point was -1.7 C so Td=1.7.

In unknown sample #2, there is 2g of the sample and 10 mL of water. Freezing point = -1.8. So Td = 1.8.

How do I obtain the molecular weights for these two unknown samples?

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#### Solution Preview

You have to use molality equations

Molality = moles of solute / kg of solvent

Td = Kf x molality

Hence, Td = Kf ...

#### Solution Summary

The molar mass of unknown samples is calculated from the freezing point data.

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