# How much does water expand when heated, and does salt affect that?

For this question, assume all things not mentioned are perfectly controlled, all at 14.7lbs of atmospheric pressure, and water is 100% pure of anything not mentioned, with no dissolved air.

Given a quantity of water that is 1 liter at 20°, what would the volume be when heated to 30°?

Secondly, the same question, except the water being heated is fully saturated with salt.

• It would be useful if scientists would translate this data into something more meaningful to lay people. For example, for 1 litre of sea water at the average salinity, the average global temperature and average air-pressure in millibars, what would be the volume be at increments of 0.5°. e.g. at what temperature would it be 1.1 litres? – Julius Marstrand Nov 19 '17 at 7:29

The volumetric expansion of a liquid is given by the following equation $$\Delta V=V_0\beta\Delta T$$ where $\beta$ is the coefficient of thermal expansion and $\Delta T$ is the change in temperature.

Here's a link to a nice table containing coefficients of expansion for water, both pure and salinated. Wikipedia shows the maximum solubility of salt in water to be around 36% (w/w).

From the first link we find that

for pure water at $25\ \mathrm{^\circ C}$: $\beta = 257\times10^{-6}/\mathrm K$

for water with 35% $\ce{NaCl}$ dissolved at $25\ \mathrm{^\circ C}$: $\beta= 297\times10^{-6}/\mathrm K$

Now you should be able to calculate the values you are interested in.

• Thanks so much. This is very interesting. For whatever reason, this morning I came up with a theory that perhaps more of the see rise we are experiencing is due to expansion than is due to new water in the oceans. Immediately after asking this question, I Googled and found that this theory is nothing new, and that expansion might actually account for 70% of sea rise. – orokusaki Aug 25 '14 at 15:24

For a starting point I would suggest http://web.mit.edu/seawater although this will not help much on the 'saturated' end of things since the salinity values in the tables do not reach the 20C saturation values. I leave finding the saturation value to the requester, since google brings it up quite easily.