(a) Why is it impossible to measure the standard reduction potential of a single half-reaction? (b) Describe how the standard reduction potential of a half-reaction can be determined.

(a) It is impossible to measure the standard reduction potential of a single half-reaction because the reduction half-reaction and the oxidation half-reaction occur simultaneously in a redox reaction, and the measured voltage or potential is a combined potential of both reactions. The standard reduction potential of a half-reaction cannot be measured in isolation, as it always depends on the other half-reaction in the overall redox reaction. (b) To determine the standard reduction potential of a half-reaction, a reference electrode with a known standard reduction potential, such as the Standard Hydrogen Electrode (SHE), is used. An electrochemical cell is set up with the reference electrode on one side and the half-reaction of interest on the other side. The cell potential (E_cell) is measured under standard conditions, and it is equal to the standard reduction potential of the half-reaction of interest when measured against the SHE. By measuring the cell potential, the standard reduction potential of the half-reaction can be determined.