When you drained the solutions from the funnel apparatus and mixed them in the beaker, the blue-purple color of the right-hand funnel vanished and...

When you drained the solutions from the funnel apparatus and mixed them in the beaker, the blue-purple color of the right-hand funnel vanished and the solution regained its original red color. Which of the following reactions occurred upon mixing together the solutions that were surrounding the two electrodes and will therefore account for the color change observed?