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Q & A: Does salt evaporate?

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Most recent answer: 11/21/2015
Q:
So, i have this lab report that i have to do and it's kinda confusing.. so we were suppose to have a salt water solution in a beaker to evaporated, i thought that some of the salt would evaporate and some would stay behind, but i was wrong. All the salt stayed behind, but i don't understand why it did... they say that salt doesn't evaporated but i want to know WHY salt doesn't evaporated. So, my question is, Does salt evaporated, and if so, why?
- Brinda (age 12)
Richmondhill, Ontario, Canada
A:

You found little or no almost no evaporation of the salt. The reason is that salts consist of electrically charged atoms (ions) like Na+ and Cl-. They can stick together in a big crystal, like the ones from a salt shaker. Those are too heavy to evaporate. They can also go into the water as separate ions. It takes a lot of energy to pull one of those charged ions out of the water, because the water molecules arrange their own charges to stick to the ions electrically. It takes much less energy to pull a water molecule out of the liquid water than it does to pull an ion out. That's why it's much easier for the water to evaporate than for the salt.

Mike W.


(published on 11/21/2015)

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