# What is the molecular mass of a substance if 22.5 g dissolved in 250 g of water produces a solution whose freezing point is -0.930°C?

##### 1 Answer

The molecular mass is 180 u.

#### Explanation:

The formula for freezing point depression is

#color(blue)(|bar(ul(color(white)(a/a) ΔT_"f" = K_"f"mcolor(white)(a/a)|)))" "#

where

We can rearrange the formula to get

In your problem,

∴

Now,

∴

The molar mass is 180 g/mol, so the molecular mass is 180 u.