My textbook states: Did you know that if you pour a handful of salt into a glass of water the water level will actually go down rather than overflowing the glass?

I tried this experiment and the glass overflowed.

I did a bit of research online and I think what the writer was referring to is that the volume of the salt solution is less than the volume of the sum of the water initially and the salt initially, not that the volume of the salt and water is less than the volume of the water alone.

Is my understanding correct here?

I'm looking for a yes/no answer if possible.

  • 1
    $\begingroup$ Search for density of salt salution for particular salt:water ratio. You can then check yourself if the volume is smaller than volume of original pure water. $\endgroup$
    – Poutnik
    Commented Nov 17, 2020 at 18:38
  • $\begingroup$ Providing yes/no answers does not fit well the site policy, focusing rather on principles than particular results. $\endgroup$
    – Poutnik
    Commented Nov 17, 2020 at 18:41
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    $\begingroup$ You obviously can't do the experiment with a full glass of water. The salt doesn't completely dissolve instantly. So initially you essentially have the volume of salt plus the volume of the salt. You could somewhat mitigate this by adding the salt slowly but you'll also need to stir somehow. // All in all this is an interesting question for you to research as Poutnik has pointed out. Frankly I'd expect some contraction at low concentrations of salt, but I'd expect that a saturated solution of sodium chloride would have a greater volume than the initial volume of water. $\endgroup$
    – MaxW
    Commented Nov 17, 2020 at 18:44
  • $\begingroup$ chemistry.stackexchange.com/questions/33058/… $\endgroup$
    – Mithoron
    Commented Nov 17, 2020 at 19:48
  • $\begingroup$ In other words: Plot the density of water + 2.16 g/ccm vs. salt content/(g/ccm) , and check if the line ever goes above one. I've never actually seen that curve! +1 $\endgroup$
    – Karl
    Commented Nov 17, 2020 at 21:41


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