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Topic: Ap Chem questions  (Read 3862 times)

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Offline gotalbin

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Ap Chem questions
« on: October 04, 2007, 03:40:07 PM »
A 3.00 g sample of an alloy  (containing Pb and Sn) was dissolved in nitric acid (HNO3. Sulfuric acid was added to this solution, which precipitated 2.93 g of PbSO4. Assuming that all of the lead was precipitated, what is the percentage of Sn in the sample?

Do we find the amount of grams in lead by dividing 207 by its molecular weight (303.3) and then multiplying by 2.93 to get 1.99 grams of Lead in Lead sulfate. I am not sure this is right. Please help.
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Offline DevaDevil

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Re: Ap Chem questions
« Reply #1 on: October 04, 2007, 03:42:06 PM »
how many moles is 2.93 g. of lead sulfate?

then how many original grams of lead would that have been.

then you have the mass% of lead, and also the mass% of Sn
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Offline gotalbin

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Re: Ap Chem questions
« Reply #2 on: October 04, 2007, 07:51:52 PM »
wait im not sure i understand...find the number of moles for lead sulfate and then do what?
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Online Borek

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Re: Ap Chem questions
« Reply #3 on: October 05, 2007, 02:44:40 AM »
Quote from: gotalbin on October 04, 2007, 07:51:52 PM
wait im not sure i understand...find the number of moles for lead sulfate and then do what?

Than how many grams of lead do you have in this sulfate.
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