Electrochemistry of Voltaic Cells: Batteries are voltaic cells. A typical AA battery is labeled as providing an electrical potential of 1.5 V. After a long period of time, a battery in use may no longer provide enough electrical power to the device. Suppose you have checked an old battery with a voltage probe and measured a potential of 0.9 V. What chemical change could be responsible for this change in voltage (and power)? Write one or two complete sentences to explain this change from an electrochemical perspective. Be specific! (“The battery died” may be true, but you should explain how it died.)