What is a reversible reaction?

A reaction that can proceed in both the forward and reverse directions under the same conditions.

What is dynamic equilibrium?

A state in which forward and reverse processes continue at equal rates, leaving the concentrations of the participating species constant over time.

Why does the forward rate decrease as $N_2O_4$ decomposes?

The forward rate is proportional to the concentration of $N_2O_4$. As $N_2O_4$ is consumed, its concentration falls and the forward rate slows.

Why does the reverse rate increase as $NO_2$ forms?

The reverse reaction uses $NO_2$. As its concentration rises, the reverse rate increases; for this elementary process, the rate is $k_r[NO_2]^2$.

How can vaporization and condensation establish equilibrium?

In a sealed container, vaporization produces gas while condensation returns gas to liquid. Equilibrium occurs when these opposing processes happen at equal rates.

General chemistryLesson 1 of 4 in the course Fundamental Equilibrium Concepts

Dynamic Equilibrium in Reversible Reactions and Phase Changes

5 flashcards · 5 quiz questions · 5 match pairs · 4 fill-in sentences · English

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Summary

Chemical equilibrium describes a state in which a reversible process continues in both directions, but the forward and reverse rates are equal. Understanding this idea helps explain why concentrations can remain steady even while reactions continue to occur.

By convention, reactants are written to the left of a reaction arrow and products to the right. A single arrow indicates the reaction as written proceeds from reactants to products. A reversible reaction can proceed in both directions, so it is represented with a double arrow.

All flashcards

What is a reversible reaction?: A reaction that can proceed in both the forward and reverse directions under the same conditions.
What is dynamic equilibrium?: A state in which forward and reverse processes continue at equal rates, leaving the concentrations of the participating species constant over time.
Why does the forward rate decrease as $N_2O_4$ decomposes?: The forward rate is proportional to the concentration of $N_2O_4$ . As $N_2O_4$ is consumed, its concentration falls and the forward rate slows.
Why does the reverse rate increase as $NO_2$ forms?: The reverse reaction uses $NO_2$ . As its concentration rises, the reverse rate increases; for this elementary process, the rate is $k_r[NO_2]^2$ .
How can vaporization and condensation establish equilibrium?: In a sealed container, vaporization produces gas while condensation returns gas to liquid. Equilibrium occurs when these opposing processes happen at equal rates.

Quiz questions

In a conventional chemical equation, where are reactants and products written?Answer: Reactants are written on the left and products on the right.
A container initially holds $N_2O_4$ but no $NO_2$ . Which statement describes the reaction rates at that point?Answer: The forward rate is nonzero, while the reverse rate is zero.
As $N_2O_4$ decomposes and $NO_2$ accumulates, how do the forward and reverse rates change?Answer: The forward rate decreases and the reverse rate increases.
What happens to the reactions at dynamic equilibrium?Answer: Both directions continue, even though concentrations remain constant.
In a sealed container at equilibrium between liquid bromine and bromine vapor, what is true?Answer: Vaporization and condensation continue at equal rates.

Based on Chemistry 2e by Paul Flowers, Klaus Theopold, Richard Langley, William R. Robinson, PhD (OpenStax), licensed CC BY 4.0. Adapted into a summary, flashcards and quizzes.

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