Which half-reaction represents reduction?
Choose one answer.
a. Cu → Cu^+2 + 2e-
b. Fe^+2 → Fe^+3 + 1e-
c. Ag^+1 + 1e- → Ag
d. Al → Al^+3 + 3e-
The half-reaction that represents reduction is option c. Ag^+1 + 1e- → Ag.
To determine which half-reaction represents reduction, we need to look for the reaction in which the oxidation state of the element decreases. The oxidation state, also known as the oxidation number, is the charge that an atom would have if all the bonding electrons were assigned to the more electronegative atom.
Now, let's analyze each option:
a. Cu → Cu^+2 + 2e-
In this reaction, the oxidation state of copper changes from 0 to +2. The oxidation state increases, indicating oxidation rather than reduction.
b. Fe^+2 → Fe^+3 + 1e-
In this reaction, the oxidation state of iron changes from +2 to +3. The oxidation state increases, indicating oxidation rather than reduction.
c. Ag^+1 + 1e- → Ag
In this reaction, the oxidation state of silver changes from +1 to 0. The oxidation state decreases, indicating reduction.
d. Al → Al^+3 + 3e-
In this reaction, the oxidation state of aluminum changes from 0 to +3. The oxidation state increases, indicating oxidation rather than reduction.
Based on the analysis, the half-reaction that represents reduction is c. Ag^+1 + 1e- → Ag.
56j5
Remember the definitions.
Oxidation is the loss of electrons.
Reduction is the gain of electrons.
The mnemonic for this is LEO the lion goes GRRR. LEO---loss electrons oxidation. If you know that you know reduction is the opposite.