What happens to the temperature of a liquid as it evaporates?

Question

a.) it decreases
b.) it stays constant
c.) it increases
d.) it varies, depending of the identitiy of the liquid

Answer 1

a.) It decreases.

This is because only the most energetic particles evaporate. They need to achieve the evaporation temperature, and then also absorb the energy of vaporization. This can happen to individual particles even when the liquid as a whole is not near this temperature. Because only the most energetic particles evaporate, the remaining particles will have a lower internal energy, and thus a lower temperature.

Answer 2

While the other answers are totally correct, you should take some responsibility yourself. Haven't you ever gone out and got a wet shirt? Do you get hot or cold? The evaporating water makes this happen. What about sweating. Why do we sweat and when? When we are hot we sweat and the result cools us down. The evaporating sweat absorbs heat energy. Why does a dog pant in hot weather? He can't sweat due to the fur coat so how else can he evaporate the water? Newton didn't have other people to ask so he had to spend more time thinking about the things that were around him. All the evidence is there around you so BE a physicist and take note of it.

Answer 3

a.) it decreases

The most energetic molecules of a liquid evaporate, taking energy with them from the liquid left behind, reducing the temperature of that liquid.

Additional info: a molecule that reaches the gaseous state remains at the same temperature until it interacts with another molecule. The more energetic a molecule (faster moving), the higher it's temperature. Conversely the less energetic a molecule (slower moving) the lower its temperature.

Newton's 1st law of motion: A body in motion will remain in motion until acted on by another body. A body at rest will remain at rest, until acted on by another body.

This means a molecule's temperature won't change, until the molecule's velocity increases or decreases by interaction with another molecule.

Answer 4

a. The reason is that to evaporate the liquid needs energy (heat) to change states (latent heat of evaporation). It draws this heat from its surroundings so the liquid that remains is cooled.

Answer 5

The answer is a), decreases. If a molecule will evaporate (e.g gain energy), then the molecules left will have less energy (e.g, they will cool down).