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CHEM 141
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Thermodynamics Definitions

Internal Energy (E) is the total thermal energy in a system.

Work (W) is the work done ON the system.

Heat (q) is the heat added to a system.

Therefore ΔE = q + W     with  W = -PΔV

Adiabatic:  A process for which no heat is exchanged with the system

Adiabatic:   ΔE = W

At constant pressure,  q = H     H is enthalpy

At constant volume   ΔE = q

Exothermic:  A chemical process which produces heat.  ΔH < 0

Endothermic:  A chemical process which absorbs heat.   ΔH > 0

Def:  A state function is a variable whose change only depends on the beginning and final state.  The state function is independent of path taken.


1. The specific heat of a substance is the heat required to raise one gram of that substance by one degree centigrade.   (units: J/gC)

2. The heat capacity of a system is the heat required to raise that particular system by one degree centigrade.    (units J/C)

Last Updated: 11/17/2014
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