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Postby MorganYun1H » Wed Jan 24, 2018 1:44 pm

Can someone explain why qp=deltaH at constant pressure?

Anna Okabe
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Re: qp=deltaH

Postby Anna Okabe » Wed Jan 24, 2018 3:30 pm

qp=delta H because the definition of enthalpy (H) is the amount of heat released/absorbed at a constant pressure. Therefore, q, being heat, equals delta H

Brigitte Phung 1F
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Re: qp=deltaH

Postby Brigitte Phung 1F » Wed Jan 24, 2018 4:14 pm

This can also be proven with equations. Because ΔH = ΔU + PΔV and ΔU = q + w, you can plug ΔU into the ΔH equation as follows: ΔH = q + w + PΔV. Because w = -PΔV, the last two terms cancel each other out: ΔH = q - PΔV + PΔV, leaving us with ΔH = q at constant pressure. Hope this helps!

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