21 terms

# Chapter 6

Energy, Work, Heat, and Enthalpy
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Energy: define
capacity to do work or produce heat
1st law of thermodynamics
energy is conserved
potential E
stored energy
kinetic E
energy due to motion
internal E?
potential+kinetic energies
internal E can be changed by
work and heat
(delta) E =
q + w
Work: define
force applied over a distance
what is w for
an expanding/contracting gas
w =
-P(delta)V
Heat: define
E flow due to temp difference
exothermic
E as heat flows out of a system
endothermic
E as heat flows into a system
How is it measured
chemical reactions = calorimetry
Enthalpy
H
H =
E + PV
State Functions
Yes- Energy (E), Enthalpy (H)

No- Heat, Work (w)
Hess's Law
the change in enthalpy is going from a given set of reactants to a given set of products is the same no matter how many steps it takes
Standard enthalpy of formation
used to calculate (delta) H for a chemical reaction
(delta) H (standard) reaction =
sum of moles of productchange in enthalpy of products -- sum of moles of reactantschange in enthalpy of reactants
path-dependent function
dependent on the amounts given