Compare these theoretical cell potential differences with those you actually measured and calculate the percentage error for each cell. Comment on pos- sible sources of error in your measurements Answer the following questions: 4.

a. For one pairing that initially gave a negative voltage reading, write the redox equation, identify the anode and cathode, and give the direction of flow of electricity in the external circuit.
b. What is the purpose of the KNO3 salt bridge?
c. A galvanic cell cannot generate electricity forever. List two chemical rea- sons you can think of for why a galvanic cell may go "dead.