Gen Chem Day 7 Flashcards
(42 cards)
change in heat, not state funciton
Q
a function that only depends upon the inital and final states of the system, being independent of the pathway taken
state function
Enthalpy
H
exothermic
H<0 releases heat
endothermic
H>0 needs heat
change H=
qp… pressure of heat
Hess’s law… ways to calculate H
pick the ones that add up to your goal
Bond dissociation energy
Change H= sum D broken- sum D formed
Bond breaking is
endothermic
Bond making is
exothermic
Enthalpies of Formation
change H= sum n H products - sum n H reactants
forms 1 mole of a single substance from its component elements in their standard states
formation rxn
Calorie
1000 cal
Calorimetry
q=CchangeT or q=mcchangeT
Entropy (S)
phases of matter S=sum S products - sum S reactants… focus on moles
c= specific heat
4.184 J/ g*c
Temp does
Not change during phase change
G<0
spontaneous
G>0
nonspontaneous
G=0
at equilbrium
Gas in a piston
- Transfer of heat (lock piston)
2. Expanding gases cool; compressing gases warm (real, not ideal)
Isobaric
(change P=0… no change in pressure
isochoric
change V = 0 so w=0… no work
isothermal
change T =0 so change E=0 NOCHANGE