---
title: "A sealed, rigid reaction vessel is initially charged with \\(\\text{H}_2\\text{(g)}\\) and \\(\\text{I}_2\\text{(g)}\\) at a constant temperature. The mixture reacts and reaches chemical equilibrium according to the following equation:  \\[ \\text{H}_2\\text{(g)} + \\text{I}_2\\text{(g)} \\rightleftharpoons 2\\,\\text{HI(g)} \\]  Once equilibrium is established, the concentration of each species in the vessel remains constant over time. Which of the following statements correctly explains this observation?"
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url: "https://nerd-notes.com/ubq/119695/"
date_modified: "2026-08-21T08:12:04+00:00"
---

# A sealed, rigid reaction vessel is initially charged with \(\text{H}_2\text{(g)}\) and \(\text{I}_2\text{(g)}\) at a constant temperature. The mixture reacts and reaches chemical equilibrium according to the following equation:

\[ \text{H}_2\text{(g)} + \text{I}_2\text{(g)} \rightleftharpoons 2\,\text{HI(g)} \]

Once equilibrium is established, the concentration of each species in the vessel remains constant over time. Which of the following statements correctly explains this observation?

A sealed, rigid reaction vessel is initially charged with \(\text{H}_2\text{(g)}\) and \(\text{I}_2\text{(g)}\) at a constant temperature. The mixture reacts and reaches chemical equilibrium according to the following equation:

\[ \text{H}_2\text{(g)} + \text{I}_2\text{(g)} \rightleftharpoons 2\,\text{HI(g)} \]

Once equilibrium is established, the concentration of each species in the vessel remains constant over time. Which of the following statements correctly explains this observation?

- **A.** The forward and reverse reactions have stopped because the initial reactants have been completely consumed.
- **B.** The forward and reverse reactions proceed at different rates because the concentrations of reactants and products must be equal at equilibrium.
- **C.** The forward and reverse reactions continue to occur at equal rates because \(\text{HI(g)}\) is formed at the same rate that it decomposes.
- **D.** The forward reaction rate exceeds the reverse reaction rate because product molecules are continuously colliding to reform reactants.

*The answer key and step-by-step explanation are available to logged-in users at https://nerd-notes.com/ubq/119695/*