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Having problem solving this free response question, help..

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September 14, 2006 - 19:36
#1
Peter Truong
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Having problem solving this free response question, help..

hi, i m new to AP chem, this is my second week in that class , and our teacher assigned this AP Exam question from 1970 to us.

A 2.000 gram sample containing graphite (carbon) and an inert substance was burned in oxygen and produced a mixture of carbon dioxide and carbon monoxide in the mole ratio 2.00 : 1.00. The volume of oxygen used was 747.0 milliliters at 1,092 K and 12.00 atmospheres pressure. Calculate the percentage by weight of graphite in the original mixture.

Can anyone tell my what it's asking, how to solve it, and the answer?

Thanks!

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September 19, 2006 - 05:31
(Reply to #1)
Armando
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I can't believe I forgot this already, I took AP Chemistry just last year.

While I will not solve it for you, I can tell you that you most likely want to use PV=nRT. Make sure you convert your units accordingly to use them in the formula.

I'm not 100% sure, however, so double check.

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September 19, 2006 - 13:08
(Reply to #2)
pianogirl2422
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Don't feel too bad Armando. I took it last year, and I forgot already as well. I'm in honors chemistry this semester too studying to be a chemical engineer. I'm sure it'll come back to me...sometime

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