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Found in: Page 468

### College Physics (Urone)

Book edition 1st Edition
Author(s) Paul Peter Urone
Pages 1272 pages
ISBN 9781938168000

# Question: Why does a beaker of 40.0ºC water placed in a vacuum chamber start to boil as the chamber is evacuated (air is pumped out of the chamber)? At what pressure does the boiling begin? Would food cook any faster in such a beaker?

When the air is evaporated from the chamber, the pressure inside is around 0 atm. So water boils at a low temperature. So it takes more time to cook the food than usual.

See the step by step solution

## Step 1: Water boiling and pressure

Boiling temperature is directly proportional to the pressure. ie, if pressure is low, then boiling point is also lowered and vice versa

## Step 2: Explanation

The beaker contains water of , which starts to boil in the vacuum chamber when the air is evacuated. Because, when the air is evacuated, vapor pressure inside the chamber will decrease. Due to this boiling temperature also get decreased. So the water starts boiling at a low temperature.

When the air is evaporated, the net pressure inside the chamber is 0 atm. Due to the very low pressure, water starts boiling at 0 atm.

Due to this low pressure, water boils at a very low temperature. So the time of cooking will increase. And also the food does not cook faster in this beaker.