Question

The vapour pressure of a solution having 0.9 mole fraction of water in ethanol water is :

• A. $39.3$
• B. $11.20$
• C. $34$
• D. $33.92$

Answer 1

The correct option is D $33.92$

The vapour pressure of a solution having 0.9 mole fraction of water in ethanol water is 33.92 mm Hg.
Mole fraction of ethanol = 1 - 0.9 = 0.1 mol
$P_M=P_{H_{2}O}^0\cdot X_{H_{2}O}+P_{ethanol}^0\cdot X_{ethanol}$
$=32.8\times 0.9+44\times 0.1$
$=33.92mmHg$