Question

The relationship between osmotic pressure at $273\, K$ when $10\, g$ glucose $(p_1), \,10\, g$ urea $(p_2)$ and $10\, g$ sucrose $(p_3)$ are dissolved in $250\, mL$ of water, is

• A. $P_1 > P_2 > P_3$
• B. $P_3 > P_1 > P_2$
• C. $P_2 > P_1 > P_3$
• D. $P_2 > P_3 > P_1$

Answer 1

Answer: (C)

$P_2 > P_1 > P_3$

Answer 2

Equal weight (10 g) of all electrolytes has been used. Higher the molecular weight, lower the number of moles and lower the magnitude of colligative properties. i.e.; osmotic pressure. Molecular weight order : sucrose > glucose > urea. Osmotic pressure order: urea > glucose > sucrose.