Question

Hi I need with with a prelab calculation for a Hydrate Crystal lab and I am so confused @_@ You don't really need to solve it if you don't want to, I just need an example on how to do these problems

1) Find the mass of the water that evaporated upon heating
- Mass of crucible is 15.12g
- Mass of crucible and CuSO4 • ?H2O is 15.67g
- Mass of crucible and CuSO4 after heating is 15.43g

2) Find the mass of the CuSO4 (without water)
3) Find the mols of water evaporated
4) Find the mols of CuSO4
5) Find the ratio of mols water to mols CuSO4
6) Write the formula for the hydrate CuSO4 • ?H2O

Answer 1

15.67g = mass xble + CuSO4.?H2O
-15.12g = mass sble
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difference is mass CuSO4.?H2O

15.43g = mass xble and CuSO4
-15.12g = mass xble
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difference is mass CuSO4 after heating.

mass CuSO4.?H2O
-mass CuSO4
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differece is mass H2O lost.

mols H2O = grams H2O/molar mass H2O
mols CuSO4 = grams/molar mass CuSO4.

Find the ratio for 1 mol CuSO4 to x mols H2O and that becomes the formula of the hydrate. CuSO4.xH2O