Heat/Enthalpy Question

[CaliRx]

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For the reaction below, how much heat would be generated from 10.0g of methane reacting with 64g of oxygen? [MW (CH4) = 16g; MW(O2) = 32g]

CH4 + 2O2 --> CO2 + 2H20

deltaH = -890.3kJ

I can't seem to get the correct answer. The approach that I took is I found the limiting reagent which is CH4 and then I used the mole ratio 1:2 to get the moles of O2. Then I multipled that by delta H. What am I doing wrong?

 

[TheRxQueen]

Methane is the limiting reactant, so once that is determined, I don't think O2 plays a part in the calculations for the answer in this case.

With the 10g of methane, you find the number of moles, which is 0.625.

If one mole of CH4 generates 890.3 kJ of heat, how much does 0.625 generate? Is the answer something around 556 kJ?

(This problem looks familiar to me, but I can't find it in my notes to confirm.)

 

[Knickerbocker]

Someone asked the same question yesterday, and I answered it, but I got no thank you.

http://forums.studentdoctor.net/showthread.php?t=438766

 

[TheRxQueen]

THAT'S why this problem looked so familar 😀

The good news is that your explanation stuck with me, Knickerbocker.

 

[CaliRx]

Thank you TheRxQueen and Knickerbocker. Recently, I’ve only been around the pcat forum and not the pre-pharmacy. That is why I missed the other thread.