Question

The molecular weight of sodium chloride determined by measuring the osmotic pressure of its aqueous solution is ______.

Options

• double the theoretical value

• same as the theoretical value

• half the theoretical value

• three times the theoretical value

Answer 1

The molecular weight of sodium chloride determined by measuring the osmotic pressure of its aqueous solution is half the theoretical value.

Explanation:

Sodium chloride (NaCl) is an electrolyte and dissociates completely in water into 2 ions, Na⁺ and Cl⁻. Osmotic pressure is a colligative property, depending on the number of solute particles. Due to dissociation, the effective number of particles doubles, leading to greater osmotic pressure. This makes the observed molecular weight appear half of the actual value.