# Chemistry

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A student recorded the following data for copper sulfate pentahydrate.
Weight of crucible and cover (after heating to constant weight), 28.120g
Weight of covered crucible plus sample, 31.020g
Weight of covered crucible plus sample after heating to constant weight, 30.020g
calculate the percentage of water in the hydrate. determine experimental error

%water in hydrate=48.5%

now what? how do i determine %water in hydrate from the given data? and then find the error?

• Chemistry -

Yes, determine the % from the data, then find error.

• Chemistry -

I don't understand how to determine the % from the data...

• Chemistry -

What's the 48.5%?
mass hydrated sample = 31.020-28.120 = ??
mass water = 31.020-30.020 = ??

%H2O = [mass water/mass hydrate ]*100 = ??
Check my numbers carefully.

• Chemistry -

34.48%, percentage water of hydrate, final answer?

• Chemistry -

right. 34.48% water.
I assume this is an experiment you did. Theoretical number is
[5*18.015/249.686]*100 = 36.08%.
Pretty good. Less than 5% error.

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