Question

Two liquids A & B are mixed together to form a solution in which A - B attractive forces are weaker than A-A & B-B attractive forces. What will be the vapour pressure of the solution?

• A. More than expected
• B. Less than expected
• C. Doesn’t Change
• D. None of the above

Answer 1

The correct option is A More than expected

Given A-B attractive forces are weaker than A-A and B-B attractive forces. As the stronger forces are replaced by the weaker forces, the molecules can easily escape into the gaseous state.
If the liquid can easily turn into a gas, it has a high vapour pressure. That’s why volatile liquids have a high vapour pressure (Example petrol has a greater vapour pressure than water.)
So, the vapour of the solution is more than expected.