ch9 - energetics Flashcards
first law of thermodynamics
energy is neither created nor destroyed
q
heat absorbed by the system, q<0 heat exits system, q>0 heat enters system
w
work done on system, w<0 work done by system, w>0 work done on system
E=
q+w
endothermic
heat goes into the system (q>0)
exothermic
heat exits the system (q<0)
uphill in enthalpy
endothermic
downhill in enthalpy
exothermic
second law of thermodynamics
entropy of universe increases in all spontaneous processes
gibbs free energy change
g=h-ts
g<0
forward rxn is spontaneous
g>0
reverse rxn is spontaneous
g=0
rxn is at equilibrium
transition state
species present at energy max
activation energy (energy barrier)
energy required to form the transition state
rate of rxn
rate at which reactant is consumed/product is produced
rate constant
k[reactants]
catalyst
speeds up rate of rxn without being changed by rxn
intermediates
formed in rxn and consumed later
equilibrium constant (K)
[products]/[reactants]
K is large for
exothermic rxns and small for endo
le chateliers principle
systems at equilibrium respond to stress in a way to minimize stress
amount of product in exothermic reaction can be increased by
decreasing temp, adding more reactant, or removing other products
