Question

A 250 mL water solution containing 48.0 g of sucrose. $C_{12}{H}_{22}{O}_{11},$ at 300 K is sesparated from pure water by means of a semipermeable membrane. What pressure must be applied above the solution in order to just prevent osmosis?

• A. $6.9atm$
• B. $9.4atm$
• C. $13.8atm$
• D. $18.8atm$

Answer 1

The correct option is C $13.8atm$

The molar mass of sucrose is $342$ g/mol.

$48.0$ g of sucrose in $250$ mL corresponds to $\frac{48}{342\times 0.250}=0.561M$ solution

The osmotic pressure is given by $\Pi =CRT=0.561\times 0.08206\times 300=13.8atm$