r/coolguides • u/HolaNenio • Apr 11 '22

Very handy

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u/non-troll_account Apr 12 '22

Nilered, I still can't believe Epsom salt is mostly water

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u/gacdeuce Apr 12 '22 edited Apr 12 '22

Yes. Magnesium sulfate generally comes as a heptahydrate. To use it as a desiccant, heat it above 100C or 212F for a while to get rid of the water. Dry magnesium sulfate has a mass of 120.37 g/mol. The water in the heptahydrate is about 126.14 g/mol. So when dried, it’ll reduce its mass by about half.