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Topic: gravimetric analysis  (Read 3106 times)

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Offline steph_r

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gravimetric analysis
« on: November 22, 2008, 10:24:36 PM »
Hi all,
I have a question that im unsure of..

An impure sample of Iron(II) Sulfate, weighing 1.545g was treated to produce a precipitate of Fe2O3. If the mass of the dried precipitate was 0.315g, calculate the percentage of iron in the sample.

Ive worked out the mol of Fe2O3
n(Fe2O3) = 0.315/159.7 = 0.00197 mol.

Im not sure how to write an equation either. Do I need it anway? How would i work out the mol ratio?

Cheers
Thank u in advance

Offline JGK

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Re: gravimetric analysis
« Reply #1 on: November 22, 2008, 10:36:16 PM »
1. The equation is not necessary.

2 Conversion of weight of Fe2O3 to moles is not necessary.

3. This a simple mathematical problem.

4. Based on atomic and molecular weights, what is the percentage of Fe in Fe2O3?

5. Using the percentage from 4, what is the weight iron in the mass of Fe2O3 produced by the reaction?

6. Taking the answer from 5, express it as a percentage of the original sample mass, Job done
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Offline steph_r

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Re: gravimetric analysis
« Reply #2 on: November 22, 2008, 10:43:32 PM »
Oh i see! I was trying to make a simple question harder..

Thank you very much for your help  :)

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