Question

What will be the correct order of vapour pressure of water, acetone and ether at ${30}^{\circ }C$. Given that among these compounds, water has maximum boiling point and ether has minimum boiling point.

• A. Ether < Acetone < Water
• B. Water < Ether < Acetone
• C. Water < Acetone < Ether
• D. Acetone < Ether < Water

Answer 1

The correct option is C Water < Acetone < Ether

We know that boiling point is the temperature at which vapour pressure of liquid is equal to atmospheric pressure.

Hence, more volatile the liquid, it requires less temperature to raise the vapour pressure of liquid to the external atmospheric pressure.

We have $bp\propto \frac{1}{Vapourpressure}$

i) Water has maximum boiling point among the other liquid and hence, it will have low vapour pressure.

ii) Similarly for Ether which have minimum boiling point and hence have maximum vapour pressure.

Therefore, the correct answer is option (B).