22.5 Free energy Flashcards
what is feasibility?
whether a reaction is able to happen and is energetically feasible
what is Gibbs’ equation?
when is a reaction feasible?
when the free energy change is less than 0
what are the limitations of feasibilty?
it does not take into account the kinetics or rate of reaction
what does feasibility depend upon?
the relationship between ΔH and -TΔS
at higher temperatures what happens to -TΔS
becomes more negative
at lower temperatures what happens to -TΔS
becomes more positive
when is a reaction ALWAYS FEASIBLE?
when ΔH is negative
and
ΔS is positive
means that TΔS is positive
which means that -TΔS is negative
will always give a negative ΔG
when is a reaction ALWAYS UNFEASIBLE?
when ΔH is positive
and
ΔS is negative
means that TΔS is negative
which means that -TΔS is positive
so will always give a positive ΔG
what happens when ΔH is positive and ΔS is positive?
how to make reaction feasible
you must change the temperature to make reaction more feasible
increasing the temperature makes TΔS more positive
which means -TΔS is more negative
at a HIGH enough temperature the -TΔS will be negative enough to outweigh the ΔH
so ΔG becomes negative so reaction is feasible
what happens when ΔH is negative and ΔS is negative?
how to make reaction feasible
you must change the temperature to make reaction more feasible
decreasing temperature makes TΔS less negative
which means -TΔS is less positive
at LOW enough temperatures the -TΔS will not be positive enough to outweigh the ΔH
so ΔG remains negative so reaction is feasible
