1)
Mass of crucible, lid and hydrated salt 21.171(g)
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Mass of crucible and lid 18.733(g)
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---> Mass of hydrated salt : (21.171 - 18.733) = 2.438 (g)
2)
Mass of crucible, lid and hydrated salt (salt + water): 21.171(g)
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Mass of crucible, lid and anhydrous salt (salt only) : 20.122(g)
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---> Mass of water : (21.171 - 20.122) = 1.049(g)
The percent water in the hydrated salt: (mH2O/mhydrate salt) * 100 = (1.049/2.438)*100 = 43.03o/o
The percent by mass of water in copper(II)sulfate pentahydrate, CuSO4 . 5H2O:
( Molar mass of 5H2O/Molar mass of CuSO
4 . 5H2O)*100 = [(5*18)/(5*18 + 63.55 + 32.07 + 16*4)]*100 = (90/249.62)*100 = 36.05
o/
o
Mass due to waters of crystalization is present in a 50.0 g sample of CuSO4 . H2O
Molar mass of CuSO4 . H2O : 63.55 + 32.07 + (16*4) + (1.008*2)+16.00 = 177.64g/mol
Molar mass of H2O: (1.008*2) + 16.00 = 18.02g/mol
In 177.64g CuSO4 . H2O, there is 18.02g H2O
---->in a 50.0 g sample of CuSO4 . H2O, there is:
50.0g CuSO4 . H2O * (18.02g H2O / 177.64g CuSO4 . H2O) = 5.07g H2O