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Dina
Dina asked in Science & MathematicsChemistry · 1 decade ago

When calculating the percentage of water of crystallization (in an alum) by mass, do we take the ratio of.....?

.....(water mass/alum mass)x100% or the ratio:

(water mass/anhydrous salt mass)x100%?

3 Answers

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  • Dr W
    Lv 7
    1 decade ago
    Favorite Answer

    % water = mass water / mass total x 100%

    so the answer is (water mass / alum mass) x 100%

  • darkskies4evr
    Lv 4
    1 decade ago

    Use:

    (water mass/alum mass)x100%

    You want the percentage mass of water in the alum, not the anhydrous salt.

  • mackley
    Lv 4
    4 years ago

    mw of CaSO4 is 136.14 g/mol (anhydrous) a hundred g CaSO4 XH2O have 20.9 g of water(mw is eighteen) or a million.sixteen mol; and seventy 9.a million g CaSO4 or 0.581 mol, so the mol relation is approx a million:2 meaning x=2 CaSO4 *2H2O

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