Comparison of the results shown in Figures and, demonstrates that the Q associated with the Ru(NH3)6 3+ mediated reduction of S2O8 2-in the presence of 220 mM C2O4 2-(Q = 2.32 C, Figure ) is substantially lower than the value when C2O4 2-is absent (Q = 6.17 C, Figure ). This observation is consistent with, and completely analogous to, the decrease in the CV peak current for Ru(NH3)6 3+ mediated reduction of S2O8 2-in the presence of C2O4 2-(Figures and), further demonstrating that that S2O8 2-is consumed by the autocatalytic reaction with C2O4 2-(Scheme 3). The Q measured from CPE (eq 20) can be expressed by eq 21, where ns and nR are the number of electrons required to reduce one molecule of S2O8 2-and Ru(NH3)6 3+ , respectively, and Ns and NR are the number of moles of S2O8 2-and Ru(NH3)6 3+ initially present in solution, respectively, and F is Faraday's constant. Rearrangement of eq 21 to eq 22 allows ns to be determined from the measurement of Q and a knowledge of nR (= 1, eq 17).