Question

what occurs during reduction in the reaction for the electrolysis of 1.0 m lif (aq)?
half-reaction | e° (v)
li⁺ + e⁻ → li | - 3.05
2h₂o + 2e⁻ → h₂ + 2oh⁻ | - 0.83
f₂ + 2e⁻ → 2f⁻ | + 2.87
o₂ + 4h⁺ + 4e⁻ → 2h₂o | + 1.23
oxygen gas is produced.
lithium ions change to solid lithium.
fluorine gas is produced.
hydrogen gas is produced.

Explanation:

In electrolysis, reduction occurs at the cathode, and the reaction with the most positive (or least negative) standard reduction potential is favored. For the reduction half - reactions here: $Li^+ + e^- \to Li$ has $E^°=- 3.05\ V$, $2H_2O + 2e^- \to H_2+2OH^-$ has $E^° = - 0.83\ V$. Since - 0.83 V is less negative (more positive) than - 3.05 V, the reduction of water to produce $H_2$ (hydrogen gas) is more favorable than the reduction of $Li^+$ to $Li$. The other options: Oxygen gas production is an oxidation process (not reduction), fluorine gas production would be an oxidation of $F^-$ (not reduction here), and the reduction of $Li^+$ is not favored over water reduction.

Answer:

D. Hydrogen gas is produced.