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chemistry

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A 2.50 g sample of a hydrate of calcium sulphate losses 0.523 g of water when heated. Determine the mass percent of water in the hydrate and the formula of the hydrate.

  • chemistry - ,

    CaSO4.XH2O

    find the mole ratio of water to CaSO4.

    moleswater=.523/18
    molesCaSO4=(2.5-.523)/molmassCaSO4

    divide moles water by the moles CaSO4, that is X

  • chemistry - ,

    percent water = (mass H2O/mass sample)*100= (0.523/2.50)*100 = 20.92 which I would round to 20.9%.

    To find the formula, take a 100 gram sample which provides
    20.9 g H2O
    100-20.9 = 79.1 g CaSO4

    moles water = 20.9/18 = 1.16
    moles CaSO4 = 79.1/136 = 0.582
    Now find the ratio of water to 1 atom of the CaSO4. The easy way to do that is to divide 0.582 by 0.582 = 1.0000 CaSO4
    Then 1.16/0.582 = ?? H2O

  • chemistry - ,

    I believe it comes out to CaSO4 x 2H20

    20.9%

    2:1 ratio

    I think haha

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