Question

Using the following portion of the activity series for oxidation half reactions:

Mn(s) → Mn^2+ (aq) + 2e
Co(s) → Co^2+ (aq) + 2e
Pt(s) → Pt^2+ (aq) + 2e
Indicate which pairs of reactions will occur.
A) Mn(s) with Pt^2+(aq) and Co^2+(aq) with Mn^2+(aq)
B) Pt(s) with Co^2+(aq) and Co(s) with Mn^2+(aq)
C) Mn(s) with Co^2+(aq) and Co(s) with Pt^2+(aq)
D) Mn(s) with Pt(s) and Co(s) with Pt(s)

Answer 1

The correct pairs of reactions according to the activity series for oxidation half-reactions are option C: Mn(s) with Co2+(aq) because Mn is more active than Co, and Co(s) will not react with Pt2+(aq) because Co is less active than Pt.

Step-by-step explanation:

To determine which pairs of redox reactions will take place, we need to consider the activity series for oxidation half-reactions:

• Mn(s) → Mn2+ (aq) + 2e−
• Co(s) → Co2+ (aq) + 2e−
• Pt(s) → Pt2+ (aq) + 2e−

Metals higher in the activity series will displace metals below them from solutions of their ions. Based on the list given, the reaction pairs are:

• A) Mn(s) with Pt2+(aq) and Co2+(aq) with Mn2+(aq)
• B) Pt(s) with Co2+(aq) and Co(s) with Mn2+(aq)
• C) Mn(s) with Co2+(aq) and Co(s) with Pt2+(aq)
• D) Mn(s) with Pt(s) and Co(s) with Pt(s)

For a reaction to occur, the solid metal must be more active (higher) in the series than the ion it is reacting with. Thus, option C is correct:

1. Mn(s) will react with Co2+(aq) because Mn is above Co in the series.
2. Co(s) will not react with Pt2+(aq) because Co is below Pt in the series.