Which of the following colligative property can provide molar mass of proteins (or polymers or colloids) with greatest precision?

Options

A. Osmotic pressure
B. Elevation in boiling point
C. Depression in freezing point
D. Relative lowing of vapor pressure

Answer

1

Explanation

The most important use of colligative properties in the laboratory is for determining the molecular mass of an unknown non-volative substance. Any of the four colligative properties can be used, but the most accurate values are obtained from osmotic-pressure measurements because the magnitude of the osmosis effect is so great. For example, a solution of `0.200 M` glucose in water at `300 K` will give an osmotic-pressure reading of `374.2 mm Hg`, a value that can easily be read to four significant figures. However, the same solution will lower the freezing point by only `0.04^(@)C`, a value that can be read to only one significant figure.