MadSci Network: Chemistry |
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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