I have learned that in primary classes that sea water is salty and I had also wondered that, what makes it salty? and my question is, where does sea water gets its salt?

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    $\begingroup$ It doesn't. The salt is already there. $\endgroup$ Apr 27, 2018 at 8:39
  • $\begingroup$ This probably should migrate to earthscience.stackexchange.com . However, see here oceanservice.noaa.gov/facts/whysalty.html $\endgroup$
    – permeakra
    Apr 27, 2018 at 8:45
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    $\begingroup$ The important idea is that salt builds up in sea water over time as small amounts are carried there in rivers but evaporation takes water back out of the sea, and deposits fresh water as rain forming the flow in rivers, but leaves the salt behind. $\endgroup$
    – matt_black
    Apr 27, 2018 at 11:23
  • $\begingroup$ Your comment has 7 up votes, could you please write a slightly more elaborate answer? $\endgroup$ May 3, 2018 at 14:38

1 Answer 1


The salt in the oceans came originally from rocks. Rain can dissolve some of the minerals found in rocks, especially rain that is slightly acidic from dissolved $\ce{CO2}$. The chemicals in the minerals are broken down into ions in solution. Some of the ions will tend to precipitate out of solution, or be taken up by living things (for example calcium is removed from water by the shells of molluscs and diatoms). Other ions will tend to build up in the water. Two of the most soluble and common ions are sodium and chloride. Over time these built up in the ocean. The sodium chloride in sea water is what makes the seas salty.


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