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Q & A: Difference between cold and warm water droplets

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Most recent answer: 10/20/2011
Q:
whats the difference betweeen a drop of cold water and a drop of hot water?
- Vanessa (age 13)
Toronto, Canada
A:
Hello Vanessa, There are several differences between a droplet of cold water and and a droplet of hot water, assuming that they both have the same mass and are kept at the same pressure. Saying that one droplet is cold and the other is hot means they have different temperatures. The cold water droplet has a lower temperature than the hot water droplet.

 The other differences discussed below are consequences of this difference in temperature. The water molecules in the hot water droplet have more energy so they will jostle around at higher speeds than the water molecules in the cold water droplet.  The rapidly moving molecules tend to not fit together as tightly as the more slowly moving ones,  so the hot water droplet will occupy a slightly larger volume than a cold water droplet with the same number of molecules.  The hot water droplet will evaporate faster than the cold water droplet. This is because the more energetic water molecules have a better chance of pulling loose from the liquid and heading off into the gas.

Maurice +mbw

(published on 10/20/2011)

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