enthalpy (h) : internal energy plus product of pressure and
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8/14/2019 Enthalpy (h) : Internal Energy Plus Product of Pressure And
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Enthalpy (h) : internal energy plus product of pressure and volume
o H = E + PV
o Change in enthalpy ( h) : heat gained or lost at constant
pressure
H = E + P V
E = q + w = q = (-P V) = q P V
Qp = E + P V = H o Reactions w/o gases
V = 0
H = E o Moles of gas doesnt change
V = 0
H = E o Moles of gas does change
H = E (or is very close) Heat of reaction ( Hrxn)
o Hfinal Hinitial = Hproducts H reactats
Endothermic: releases heat
Hfinal < Hinitial
H < 0
Endothermic : absorbs heat
Hfinal > Hinitial
H > 0
Heat of combustion ( Hcomb)
o I mole of subtance w/ O2
Heat of Formation ( Hf)
o 1 mole of compound produced
Heat of vaporization
o 1 mole of substance vaporizes
weaker bonds are easier to break than stronger bonds because they
are higher in energy