Question

A liquid is boiling in a airtight vessel. Using an exhaust tube the vapour is pumped out at a faster rate. What will happen to the liquid?
1. Temperature will go down but boiling will continue
2. Temperature will rise and boiling will continue
3. Boiling will stop
4. Vapour starts condensing

Answer 1

Correct Answer - Option 1 : Temperature will go down but boiling will continue

Explanation:

Boiling:

• The boiling point is the temperature at which a liquid boils and turns to vapour. In other words, the liquid state turns into a gaseous state. In a more scientific language, it is the temperature at which the pressure exerted by the surroundings upon a liquid is equalled by the pressure exerted by the vapour of the liquid or the vapour pressure drops below the pressure above the liquid surface.
• When a liquid is boiling in an airtight vessel, It implies that the vapour pressure is equal to or below the liquid pressure. Using the exhaust tube the vapour is pumped out, Hence the vapour pressure further decreases and boiling continue.
• As high-temperature vapour being pumped out the temperature of the vessel decreases.
• The boiling point of the water at 1 bar pressure is 100°C.
• If the pressure is decreased, the boiling point of the substance also decreases.
• At high altitudes, water boils at low temperature because atmospheric pressure decreases with an increase in altitude.