MadSci Network: Chemistry
Query:

Re: How does salt affect water's density?

Area: Chemistry
Posted By: Samuel Conway, Senior Staff Chemist, Avid Therapeutics,Philadelphia, PA
Date: Tue May 6 19:09:42 1997
Area of science: Chemistry
ID: 860953219.Ch
Message:
Adding salt to water makes the density of the solution increase.
The density of a 20% solution of sodium chloride in water is about
1.15 (CRC Handbook, 47th Ed. [shows how old *I* am!]).  So, adding
200 g of salt to a liter (1000 g) of water only increases the volume
of the solution by about 80 milliliters.

Remember, salt has a density, too, and as you add more and more of it
to the water, you are introducing something which is very heavy, yet
takes up a fairly small volume.

If you look at the flip side, adding ethanol to water makes the density
go *down*.  That is because ethanol is less dense than water, so the
more of it you mix with the water, the closer the overall density is
going to come to the density of ethanol itself.


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