Standard reduction potentials at 25 °C are given as follows:

$\mathrm{F_2 + 2e^- \rightarrow 2F^-}$ $E^\circ = +2.87\ \text{V}$

$\mathrm{Cl_2 + 2e^- \rightarrow 2Cl^-}$ $E^\circ = +1.36\ \text{V}$

$\mathrm{Br_2 + 2e^- \rightarrow 2Br^-}$ $E^\circ = +1.07\ \text{V}$

$\mathrm{O_2 + 4H^+ + 4e^- \rightarrow 2H_2O}$ $E^\circ = +1.23\ \text{V}$

Using these data, determine which of the halogens (F₂, Cl₂, Br₂) will react spontaneously with water at 25 °C. For each halogen that does react, write the balanced overall chemical equation for its reaction with water.

Question

Standard reduction potentials at 25 °C are given as follows:

$\mathrm{F_2 + 2e^- \rightarrow 2F^-}$ $E^\circ = +2.87\ \text{V}$

$\mathrm{Cl_2 + 2e^- \rightarrow 2Cl^-}$ $E^\circ = +1.36\ \text{V}$

$\mathrm{Br_2 + 2e^- \rightarrow 2Br^-}$ $E^\circ = +1.07\ \text{V}$

$\mathrm{O_2 + 4H^+ + 4e^- \rightarrow 2H_2O}$ $E^\circ = +1.23\ \text{V}$

Using these data, determine which of the halogens (F₂, Cl₂, Br₂) will react spontaneously with water at 25 °C. For each halogen that does react, write the balanced overall chemical equation for its reaction with water.

Accepted Answer

Fluorine and chlorine react spontaneously. Balanced equations: 2 F₂ + 2 H₂O → 4 HF + O₂ and 2 Cl₂ + 2 H₂O → 4 HCl + O₂.

Igcse Model Questions Vol1 2025 Chemistry Question 16

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