Chemical Forums
Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: A5HLEY on January 27, 2008, 02:47:02 PM
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I'm having trouble with a couple of homework problems concerning calculating deltaE.
There are 3 problems, and I got one out of three correct, so I don't know what I'm doing wrong.
a). A system releases 363 kJ of heat to the surroundings and does 2.0e+02 kJ of work on the surroundings;
So I did (-363) - (2e^2) = -377.7781122
and
b). q = 5.62 kJ and w = -495 J
So I converted -495 K to -.495 kJ, and did 5.62 - (-.425) = 6.115
Any ideas as to where I'm going wrong?
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The e notation means scientific notation and does not actually refer to the constant e.
2.0e+02 = 2x102 = 200
For (b) I'm not sure since some people use different conventions for the signs of q and w. Some people define w as work done on the system in which case ΔE = q + w. However, if w is defined as work done by the system, then ΔE = q - w. So, I would check on how w is defined in that particular problem.