258 ❯ STEP 4. Review the Knowledge You Need to Score High
(b) The cobalt is the anode. The reason Co is the anode is because the Co is oxidized.
You get 1 point for identifying the anode. You get 1 point for the explanation of
why Co is the anode or if you state that the Co loses electrons.
(c) The voltage would decrease. The excess Co^2 +, from the Co(NO 3 ) 2 , would impede the
reactions from proceeding as written.
Give yourself 1 point for saying decrease. Give yourself 1 point for the explanation.
(d) At equilibrium, the cell voltage would be 0 V. At equilibrium no work is done, so the
potential must be zero.
Give yourself 1 point for saying 0 V, and give yourself 1 point for the equilibrium
explanation.
(e) The electron configurations are as follows:
Co 1s^2 2s^2 2p^6 3s^2 3p^6 4s^2 3d^7 or [Ar] 4s^2 3d^7
Co^2 + 1s^2 2s^2 2p^6 3s^2 3p^6 3d^7 or [Ar] 3d^7
Give yourself 1 point for each correct electron configurations. The orbitals do not
need to be in the “correct” order, but they must have the correct superscripts.
Total your points. There are 10 points possible.❯ Rapid Review
● In redox reactions, electrons are lost and gained. Oxidation is the loss of electrons, and
reduction is the gain of electrons.
● The same number of electrons is lost and gained in redox reactions.
● Galvanic (voltaic) cells produce electricity through the use of a redox reaction.
● The anode is the electrode at which the oxidation half-reaction takes place. The anode
compartment is the solution in which the anode is immersed.
● The cathode is the electrode at which reduction takes place, and the cathode compart-
ment is the solution in which the cathode is immersed.
● A salt bridge is used in an electrochemical cell to maintain electrical neutrality in the cell
compartments.
● Be able to diagram an electrochemical cell.
● The cell notation is a shorthand way of representing a cell. It has the form:anode|anode compartment||cathode compartment|cathode
● Standard reduction potentials are used to calculate the cell potential under standard
conditions. All half-reactions are shown in the reduction form.
● For a galvanic cell E°cell > 0.
● E°cell = E°cathode - E°anode > 0. Know how to use this equation to calculate E°cell.
● Electrolytic cells use an external source of electricity to produce a desired redox reaction.
● Review how to diagram an electrolytic cell.