Concept #1:

*Electrolysis* deals with passing an electrical current through a substance in order to produce chemical changes.

Example #1:

Aluminum can be electroplated at the cathode of an electrolysis cell by the half-reaction:

Al^{3+}^{ }(aq) + 3 e ** ^{–}** → Al (s)

How much time would it take for 825 mg of aluminum to be plated at a current of 4.1 A?

Example #2:
In the electrolysis of molecular iodine to iodide ions for 0.15 M NaI solution containing 4.2 x 10** ^{-4}** M I

Practice: During electrolysis the concentration of I _{2} increases to 8.3 x 10 ** ^{-3}** M, while all other concentrations remain unchanged. If the electrical resistance is 1.8 ohms, the current is 71 mA, the anode overpotential is 0.013 V and the cathode overpotential is 0.115 V, what is the voltage needed?

Example #3:

Gold can be plated out of a solution containing Au^{3+} based on the following half reaction:

Au^{3+}^{ }(aq) + 3 e ^{–} → Au (s)

a) What mass of gold is plated by a 41 minute flow of 6.8 A current?

Example #4:

A solution of Mn^{+5} is used to plate out Mn in an electrochemical cell. If a total of 1.13 g of Mn is plated out in a total time of 1600 seconds, what was the electrical current used? (**MW of Mn is 54.94 g/mol**)

Example #5:

**EXAMPLE:** If steady current of 15 amperes is provided by a stable voltage of 12 Volts for 600 seconds, answer each of the following questions.

a) Calculate the ** total charge** that passes through the circuit in this time.

b) Calculate the ** total number of moles of electrons** that pass through the circuit in this time.

c) Calculate the ** total amount of energy** that passes through the circuit in this time.

d) Calculate the ** power** that the battery provides during this process.