Chemistry 12 Equilibrium Review – Part I and II

Part I

1) No macroscopic changes, forward and reverse rxns still occur
2) Dynamics => forward and reverse rxns are still occurring => NOT static
3) solid and liquid
4) Catalyst increase rate of rxn, establishes equm faster, has no effect on position of equm
5) Endothermic rxn consumes heat and Δ H is +
exothermic rxn produces heat and Δ H is -
6) Two factors that control equilibria are ENTHALPY and ENTROPY... four possible combinations of these are: 1) Enthalpy pushes forward & Entropy pushes forward => rxn goes to completion, 2) Enthalpy pushes forward & entropy pushes back => equm, 3) Enthalpy pushes back and entropy pushes forward => equm, 4) Enthalpy pushes back and entropy pushes back=> no rxn
7) Enthalpy pushes forward if rxn is EXOTHERMIC, enthalpy pushes back if rxn is ENDOTHERMIC, entropy pushes forward if rxn has largest # of most random phase on products side, entropy pushes back if rxn has largest # of most random phase on reactants side.
8) see your notes!!!!
9) see your notes & Hebden page 56!!!!
10) only temperature affects the value of Keq
11) Temp change:
endothermic temp incr => shift right => Keq incr,
endothermic temp decr => shift left => Keq decr
exothermic temp incr => shift left => Keq decr
exothermic temp decr => shift right => Keq incr
>Stoichiometric ratios - depends on rxn - ignore
>equation written in reverse => reciprocal since reactants and products switch places
>catalyst - no change
12) LARGE Keq => more products, less reactants, favours products, enthalpy more likely to be pushing forward...
SMALL Keq => less products, more reactants, favours reactants, enthalpy more likely to pushing backwards...

PART II - these are NOT questions - this is a LIST of quantitative skills you should have!