Which of the following is NOT true for ΔGrxn?

A.) If ΔG°rxn > 0, the reaction is spontaneous in the forward direction.
B.) If Q = 1, then ΔGrxn = ΔG°rxn.If ΔG°rxn = 0, the reaction is spontaneous in the reverse direction.
C.) If ΔG°rxn > 0, the reaction is spontaneous in the reverse direction.
D.) Under equilibrium conditions, ΔGrxn=0.

I think C and D are true; A and B are not true.

Thank you DrBob222, could you possibly elaborate why C or D could be correct? (I initially thought C, but I'm not so sure now.)

typo: *not be correct

C. If dGrxn > 0 that means it is + some number so dGrxn for the reverse reaction will be - and a negative dG means spontaneity.

D. When dG = 0 the system is at equilibrium. (because the only other possibilities are + and -; if + it goes in the reverse and if - it is spontaneous as written).

To determine which statement is NOT true for ΔGrxn (the standard Gibbs free energy change of a reaction), we can go through each of the given options.

A.) If ΔG°rxn > 0, the reaction is spontaneous in the forward direction.
This statement is true. If ΔG°rxn is positive, it means that the reaction is non-spontaneous in the forward direction because it requires energy input to proceed.

B.) If Q = 1, then ΔGrxn = ΔG°rxn.
This statement is true. In standard conditions where Q (the reaction quotient) is equal to 1, the ΔGrxn will be equal to the ΔG°rxn. The reaction is considered to be in equilibrium in this case.

C.) If ΔG°rxn > 0, the reaction is spontaneous in the reverse direction.
This statement is also true. If ΔG°rxn is positive, it means that the reaction is non-spontaneous in the forward direction. However, it can still occur spontaneously in the reverse direction, as that would lead to a decrease in the Gibbs free energy.

D.) Under equilibrium conditions, ΔGrxn = 0.
This statement is false. Under equilibrium conditions, ΔGrxn is not necessarily equal to zero. Instead, ΔGrxn = 0 represents the condition where the reaction is at equilibrium, meaning that the rates of the forward and reverse reactions are equal, but it doesn't mean that the ΔGrxn is zero. In fact, ΔGrxn = 0 corresponds to the point where the reactants and products have equal Gibbs free energies.

Therefore, the statement that is NOT true for ΔGrxn is D.) Under equilibrium conditions, ΔGrxn = 0.