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April 19, 2015

April 19, 2015

Posted by **Lou** on Monday, April 13, 2009 at 8:35pm.

Calculate the percent copper in pure copper sulfate pentahydrate(this is the theoretical percent copper). One mole of copper has a mass of 63.55 g, and by addition, one mole of CuSO4 x 5H2O has a mass of 249.5 g.

- chem -
**DrBob222**, Monday, April 13, 2009 at 8:42pmSo what's the question? Percent Cu in the sample?

(1.198/1.664)*100 = ??

Theoretical yield =

(mass Cu/mass hydrate)*100 = (63.55/249.5)*100 = ??

- chem -
**Lou**, Monday, April 13, 2009 at 8:57pmThe question is asking for percent of copper in the sample( so the first step shown above), but when I had to calculate the experimental percent I did the same thing, and i got 72%( is that the correct number of significant figures)?

I also wanted to know when I have to calculate the error of the % of copper what number do I use as true value and actual value?

- chem -
**Lou**, Monday, April 13, 2009 at 10:25pmThe mass of the CuSO4 x 5H2O sample is 1.664 g. The mass of the recovered copper is 1.198 g.

1. Compute the experimental percent by mass of copper in the sample:

1.1664/1.998x 100=71.81%

2. Calculate the percent copper in pure copper sulfate pentahydrate(this is the theoretical percent copper). One mole of copper has a mass of 63.55 g, and by addition, one mole of CuSO4 x 5H2O has a mass of 249.5 g:

63.55/249.5x100= 25.47%

3. In order to calculate the error of the % Cu and the percent error of the % Cu I know I am suppose to use 1.198 as the experimental value, but I am not sure what to use for the true value.

- chem -
**DrBob222**, Monday, April 13, 2009 at 10:43pmAnswered above.

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