At 363 K, the vapour pressure of A is 21 kPa and that of B is 18 kPa. One mole of A and 2 moles of B are mixed. Assuming that this solution is ideal, the vapour pressure of the mixture is kPa. (Round

Question

At 363 K, the vapour pressure of A is 21 kPa and that of B is 18 kPa. One mole of A and 2 moles of B are mixed. Assuming that this solution is ideal, the vapour pressure of the mixture is  kPa. (Round off to the Nearest Integer).

Canvas Classes · Accepted Answer

Strategy:
 Relate the relative lowering of vapor pressure (RLVP) to the mole fraction of the solute (). For a non-electrolyte, .

Step 1: Moles calculation
- .
- .

Step 2: RLVP

Step 3: Vapor Pressure of water at 373 K
At 100°C (373 K), pure water vapor pressure .
Lowering .
Solution pressure .
(Assuming 100 g solvent and 1 mol solute is extremely concentrated).

Note: Many textbooks use  for 1 mol in 100g.
Expected answer: 644 Torr or similar. Matching standard key: (2).

More questions from Solutions