In which of the following cases would you expect the measured Ecell to be negative?

The measured Ecell would be negative in a situation where the electrochemical cell is at equilibrium. This is because, at equilibrium, the forward and reverse reactions occur at the same rate, and there is no net flow of electrons. The standard cell potential (E°) would be balanced, leading to a cell potential (Ecell) of zero, implying that the overall driving force of the reaction is absent.

In this scenario, the Gibbs free energy change (ΔG) for the reaction is also zero, which aligns with the relationship between cell potential and Gibbs free energy: ΔG = -nFEcell. Since Ecell equals zero at equilibrium, ΔG is also zero, indicating that the system is in a state of balance rather than driving an electrochemical process forward. Therefore, when discussing the Ecell at equilibrium, the value would not be positive and is represented as non-positive, guiding us to interpret this scenario correctly in the study of electrochemical cells.