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### Measuring Heat Transfer

Posted: Sun Jan 22, 2017 7:25 pm
For the questions about measuring heat transfer, why is it that the equations for delta H are sometimes mC(delta T) and some are nC(delta T)? How would you know which equation to use?

### Re: Measuring Heat Transfer

Posted: Sun Jan 22, 2017 7:33 pm
Are delta U, q, and delta H essentially measuring the same thing?

### Re: Measuring Heat Transfer

Posted: Sun Jan 22, 2017 7:38 pm
The equation with the m in it will give you the energy supplied as heat to the substance, and the equation with the n in it will give you the molar heat capacity of a substance. The m refers to mass while the n refers to moles. You'll know which equation to use based on which one (grams or moles) the problem gives you.

### Re: Measuring Heat Transfer

Posted: Tue Jan 24, 2017 12:40 am
Delta U is only equal to delta H when the volume of reactants equals the volume of products. This is because since q = delta H at constant pressure (aka qp = delta H), delta U = qp + w, and w = 0 when the volumes are equal, delta U = qp + w = delta H + w = delta H. Hope this helped!