8. Solving a chemistry problem

2. The wave of reduction of CrO4- to Cr3 has a half-wave potential of -0.3 V, and the wave of reduction of Cr3 to Cr0 - 1.4 V. On the polarogram of waste water, the limiting current at -0.70 V is 10.5 μA, and at - 1.8 V Id=42.0 uA. Calculate the ratio of CrO4- and Cr3 concentrations in the analyzed water, assuming that the particle diffusion coefficients are equal.