A 10-mm cube of copper metal is placed in 250 mL of 12 M nitric acid at 25C and the reaction below occurs: Cu(s) + 4H+(aq) + 2NO3-(aq) Cu2+(aq) + 2NO2(g) + 2H2O(l) At a particular instant in time, nitrogen dioxide is being produced at the rate of 2.6 x 10-4 M/min. At this same instant, what is the rate at which hydrogen ions are being consumed?