Manganese traffic light How to make a traffic light from potassium permanganate Safety precautions Warning! Only under adult supervision. Reagents and equipment potassium permanganate solution; alkaline glucose solution (glucose solution + drain cleaner); glass. Step-by-step instructions Mix a potassium permanganate solution with an alkaline glucose solution (glucose solution + drain cleaner). Observe as the solution changes colors like a traffic light. Process description In an alkaline medium, glucose reduces potassium permanganate, first to potassium manganate, and then to manganese(IV) oxide. In this case, the solution changes colors from raspberry-red to green, then to brown. Cool experiments are waiting for you in the MEL Chemistry subscription!