Chemical Forums
Chemistry Forums for Students => Physical Chemistry Forum => Topic started by: Ice-cream on May 31, 2005, 10:52:03 AM
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hey guys, im finding this question really difficult and apart from getting the equations, i really don't know where to start. can any1 guide me in the right direction?
A chemist weighed out 5.14 g of a mixture containing unknown amounts of BaO(s) and CaO(s) and placed the sample in a 1.5L flask containing CO2(g) at 30 degrees C and 750 torr. After the reaction to form BaCO3(s) and CaCO3(s) was completed, the pressure of CO2(g) remaining was 230 torr. Calculate the mass of BaO(s) and CaO(s) in the mixture.
ok, well i wrote 2 equations: CaO + CO2 --> CaCO3 and BaO + CO2 --> BaCO3
i'm not sure what i should be aiming to do to get the mass of those 2 compounds...
thanx
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Use pV = nRT to find out how much CO2 is left and how much reacted - that will give you information on number of moles of oxides in the mixture - say its N. Assume there was x moles CaO and y moles BaO - x+y=N. Write down equation for mass of mixture containing x, y moles of oxides - you will have two equations and two unknowns. That's all.
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Im having trouble on the same problem...I use PV = nRT to find the number of moles of the mixture... but am not sure what equations two equations that you talk about to write. there is x + y = N. but that is only one equation. help please?
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Write down equation for mass of mixture containing x, y moles of oxides.