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Having problem solving this free response question, help..

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Peter Truong's picture
Joined: Apr 2006
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?


Armando's picture
Joined: Sep 2005

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.

pianogirl2422's picture
Joined: Mar 2005

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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