A KCl solution is prepared by dissolving 25.0 g KCl in 250.0 g of water at 25 °C.What is the vapour pressure of the solution if the vapour pressure of water at 25 °C is 23.76 mmHg?
A)21.6 mmHg
B)22.7 mmHg
C)23.2 mmHg
D)24.9 mmHg

Question

Quizplus · Accepted Answer

The vapour pressure of a solution is given by the equation: Psolution = Xsolvent * P°solvent, where Xsolvent is the mole fraction of the solvent and P°solvent is the vapour pressure of the pure solvent. To find Xsolvent, we need to calculate the moles of KCl and water separately.
moles of KCl = 25.0 g / 74.55 g/mol = 0.335 mol
moles of water = 250.0 g / 18.02 g/mol = 13.87 mol
Total moles = 0.335 + 13.87 = 14.20 mol
Xsolvent = moles of water / total moles = 13.87 / 14.20 = 0.975
Substituting this value into the equation, we get:
Psolution = 0.975 * 23.76 mmHg = 23.151 mmHg, which rounds off to 22.7 mmHg. Therefore, the correct answer is B.

A KCl Solution Is Prepared by Dissolving 25