What does a ΔG value greater than 0 indicate about a process?

A ΔG value greater than 0 indicates that the process is non-spontaneous; this means that the reaction or process will not occur without the addition of energy or work. In thermodynamics, the change in Gibbs free energy (ΔG) is a crucial indicator of a system's ability to perform work and move toward equilibrium.

When ΔG is positive, the system is at a state where it requires an input of energy to proceed to the products. This can be understood through the concept of spontaneity; a spontaneous process has a negative ΔG and can occur without external energy. Conversely, a positive ΔG implies that the forward reaction is not favored, indicating that the system is more stable in its reactants' state.

Recognizing the implications of ΔG values helps in understanding the feasibility and directionality of chemical reactions. For example, a reaction that is non-spontaneous under standard conditions may still be driven by coupling with another exergonic process, but the key takeaway is that the positive ΔG signals that additional work or energy input is necessary for the reaction to proceed.