Electrochemistry studies the interconversion of chemical and electrical energy. Electrochemical cells the experimental setup that produces an electrical current and does electrical work through the use of a redox reaction: also called voltaic or galvanic cells. Electrolysis when a chemical reaction is forced to occur in an electrochemical cell by introducing electrical current from an external source: when this occurs, the nomenclature changes from voltaic cell to electrolytic cell. Salt-bridge an inverted u-tube filled with an aqueous solution of an electrochemically inert salt. The physically separated subsystem where each half-reaction occurs is called a half-cell. Electrode the surface where each half-reaction takes place. It is an electronic conductor (usually a metal or graphite bar) that is in contact with an electrolyte (a solution or a molten salt: often the electrode is also one of the reactants. Cathode the electrode where the reduction occurs. Anode the electrode where the oxidation occurs.
Here, Zn undergoes oxidation by losing 2eâ, and the Cu2+ ions accept 2eâ to form metallic Cu, which is deposited at the copper electrode. At the zinc electrode, oxidation occurs, and hence it is known as the anode. Reduction occurs at the copper electrode, and hence it is called the cathode.
The electrochemical cell notation for this cell is Zn(s)|Zn2+(aq)||Cu2+(aq)|Cu(s).
Construction of a voltaic cell
Consider a chromium-silver voltaic cell that is constructed such that one half-cell consists of the chromium, Cr, electrode immersed in a Cr(NO3)3 solution, and the other half-cell consists of the silver, Ag, electrode immersed in a AgNO3 solution. The two electrodes are connected by a copper wire. The Cr electrode acts as the anode, and the Ag electrode acts as the cathode. To maintain electric neutrality, you add a KNO3 salt bridge separating the two half-cells. Use this information to solve Parts B, C, and D.
Part B
The half-cell is a chamber in the voltaic cell where one half-cell is the site of the oxidation reaction and the other half-cell is the site of the reduction reaction.
Type the half-cell reaction that takes place at the anode for the chromium-silver voltaic cell. Indicate the physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Use (aq) for an aqueous solution. Do not forget to add electrons in your reaction.
Express your answer as a chemical equation.
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Part C
The half-cell is a chamber in the voltaic cell where one half-cell is the site of an oxidation reaction and the other half-cell is the site of a reduction reaction.
Type the half-cell reaction that takes place at the cathode for the chromium-silver voltaic cell. Indicate physical states using the abbreviation (s), (l), or (g) for solid, liquid, or gas, respectively. Use (aq) for an aqueous solution. Do not forget to add electrons in your reaction.
