The following reaction has the following standard thermodynamic parameters:

Reaction: C(g) + D(g)----> E(g)
Delta H rxn=-26.1kJ/mol and
Delta S rxn=-69.8J/(mol*K).

Calculate the temperature at which the reaction becomes nonspontaneous.

1 answer

DG = DH -TDS
When DG is - the reaction is spontaneous, when + it is spontaneous the other direction, the mid-point is 0. Set DG = 0 and substitute DH and DS into the equation. Solve for T. Remember DH is given in kJ and DS is given in J(not kJ).