Question

Consider the following table of standard reduction potentials:

Reduction Half- reaction E∘(V)

A³⁺ +2e⁻ ⟶A⁺ 1.47
B²⁺ ⁰+2e⁻ ⟶B 0.60
C2++e⁻ ⟶C⁺ −0.21
D+e⁻ ⟶D⁻ −1.38​

Which substances can be spontaneously oxidized by B²⁺?

Answer 1

C²⁺ and D⁺ can be spontaneously oxidized by B²⁺ since they have lower standard oxidation potentials when their reduction potentials are reversed, whereas A³⁺ cannot because its standard oxidation potential is higher than that of B²⁺.

Step-by-step explanation:

To determine which substances can be spontaneously oxidized by B²⁺, we need to compare the standard reduction potentials (E⁰) of the species involved. Spontaneous oxidation occurs when a species with a lower reduction potential (more positive E⁰ when reversed for oxidation) reacts with a species having a higher reduction potential. Taking B²⁺ with an E⁰ of 0.60 V as our baseline, we look at the other substances:

• A³⁺ +2e⁻ ↯ A⁺, E⁰ = 1.47 V
• C²⁺ +e⁻ ↯ C⁺, E⁰ = -0.21 V (0.21 V for oxidation)
• D⁺ +e⁻ ↯ D⁻, E⁰ = -1.38 V (1.38 V for oxidation)

Since C²⁺ (oxidation potential 0.21 V) and D⁺ (oxidation potential 1.38 V) have lower standard oxidation potentials than B²⁺, they can be oxidized by B²⁺. A³⁺, however, has a much higher reduction potential and cannot be oxidized by B²⁺.

To confirm spontaneous reactions, look at their reduction half-reactions and their corresponding potentials. A half-reaction with a more positive E⁰ has a greater tendency to gain electrons and be reduced, hence the one with a more negative E⁰ (when flipped for oxidation) will be oxidized. Since C²⁺ and D⁺ have more negative oxidation potentials than B²⁺, they can be oxidized by B²⁺ spontaneously.