How does water start out as salt water in the ocean and end up as fresh water when it rains?



  1. 0 Votes

    When ocean water evaporates, only the water evaporates.  The salt stays in the ocean.  When salt is dissolved in water, the sodium and chloride ions are pulled apart due to their attraction to the surrounding water molecules.  When water evaporates, the water molecules move away from eachother, and they can no longer exert enough force to carry the sodium and chloride ions away with them.  The salt-free water then condenses in the atmosphere and comes back down as rain.

    You can see this for yourself by boiling a pot of salt water at home.  As the water evaporates, the water in the pot will get saltier and saltier. When it gets too salty, the sodium and chloride ions will reunite and settle to the bottom as salt, and the water will eventually all boil off and leave the salt behind.  If you cover the pot, you can even collect the fresh water when it condenses!

  2. 0 Votes

    maddie‘s explanation pretty much sums it up. You can also observe this effect without using a stove. This experiment is a closer approximation of what happens because you’ll be using the sun’s heat directly. It takes a little longer, though. Have fun!

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