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Reaction Quotients

This worksheet covers Reaction Quotients, which is part of the Equilibrium module in the Chemistry course. Practice problems are designed to strengthen key concepts and build confidence.

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Reaction Quotients

Equilibrium • Chemistry

Set 1 — Foundation

What is the reaction quotient $Q$ for the reaction $aA + bB \rightleftharpoons cC + dD$ ?

$Q = \frac{[C]^c[D]^d}{[A]^a[B]^b}$

$Q = \frac{[A]^a[B]^b}{[C]^c[D]^d}$

$Q = [C] + [D]$

$Q = [A] + [B]$

If the equilibrium constant $K$ for a reaction is 5, what can be said about the reaction if $Q < K$ ?

The reaction will proceed to the right.

The reaction will proceed to the left.

The reaction is at equilibrium.

The reaction cannot proceed.

For the reaction $N_{2}(g) + 3H_{2}(g) \rightleftharpoons 2NH_{3}(g)$ , what is the expression for the reaction quotient $Q$ ?

$Q = \frac{[NH_{3}]^{2}}{[N_{2}][H_{2}]^{3}}$

$Q = \frac{[N_{2}][H_{2}]^{3}}{[NH_{3}]^{2}}$

$Q = [N_{2}][H_{2}]$

$Q = [NH_{3}]^{2}$

Which statement correctly describes the relationship between $Q$ and $K$ ?

$Q = K$ means the system is at equilibrium.

$Q > K$ means reactants are favored.

$Q < K$ means products are favored.

$Q = K$ means no reaction occurs.

If the concentration of products in a reaction increases, what happens to $Q$ ?

$Q$ increases.

$Q$ decreases.

$Q$ remains the same.

Cannot determine without $K$ .

For the reaction $A \rightleftharpoons B$ , if $[A] = 0.2 M$ and $[B] = 0.8 M$ , what is $Q$ ?

$Q = 4$

$Q = 0.25$

$Q = 0.5$

$Q = 1$

What does a reaction quotient $Q$ of 1 imply about the reaction at that moment?

The reaction is at equilibrium.

The reactants are favored.

The products are favored.

The reaction cannot proceed.

In the reaction $C + D \rightleftharpoons E + F$ , which of the following would increase $Q$ ?

Increasing $[E]$ .

Increasing $[C]$ .

Increasing $[D]$ .

Decreasing $[F]$ .

For the reaction $2H_{2}(g) + O_{2}(g) \rightleftharpoons 2H_{2}O(g)$ , what is $Q$ if $[H_{2}] = 0.5 M$ , $[O_{2}] = 0.25 M$ , and $[H_{2}O] = 1.0 M$ ?