You take a sample of water that is at room temperature and in contact with air a

Question

You take a sample of water that is at room temperature and in contact with air and put it under a vacuum. Right away, you see bubbles leave the water, but after a little while, the bubbles stop. As you keep applying the vacuum, more bub- bles appear. A friend tells you that the first bubbles were water vapor, and the low pressure had reduced the boiling point of water, causing the water to boil. Another friend tells you that the first bubbles were gas molecules from the air (oxygen, nitrogen, and so forth) that were dissolved in the water. Which friend is mostly likely to be correct? What, then, is responsible for the second batch of bubbles?

Explanation / Answer

First friend is correct.

As we know that boiling is phenomenon of both pressure and temperature.Here on then earth atmosphere water boils at 100 °C because here pressure is 1atm.You know even water can boil at 0 °C if it's pressure is reduced very much.

In vacuum there is no pressure.So when water is put under vacuum it reduces the boiling point of water.The formation of bubbles is due to water vapour not any air gap.As we continuous applying vacuum there is batch of bubbles formation and after sometime all the water will convert into vapour.

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