Equilibrium Practice Questions
IB (International Baccalaureate) · IB Chemistry HL · 150 free MCQs with instant results and detailed explanations.
150
Total
47
Easy
78
Medium
25
Hard
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Sample Questions from Equilibrium
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Q1
Easy
What is the definition of dynamic equilibrium in a chemical reaction?
A.
The rates of the forward and reverse reactions are equal.
B.
The concentrations of reactants and products are equal.
C.
All reactants are completely converted to products.
D.
The reaction only occurs in one direction.
Show Answer & Explanation
Correct Answer: A
Dynamic equilibrium occurs when the rates of the forward and reverse reactions are equal, leading to constant concentrations of reactants and products over time.
Q2
Easy
For the equilibrium reaction: 2A(g) ⇌ B(g) + C(g), if the concentration of A is increased, what will happen to the position of equilibrium?
A.
Shift to the right, producing more B and C.
B.
Shift to the left, producing more A.
C.
Remain unchanged.
D.
Shift to the right, consuming more B and C.
Show Answer & Explanation
Correct Answer: A
According to Le Chatelier's principle, increasing the concentration of a reactant (A) will shift the equilibrium position to the right to produce more products (B and C) in order to counteract the change.
Q3
Easy
A 1.0 M solution of acetic acid (CH3COOH) is in equilibrium with its dissociated ions. If the equilibrium constant (Ka) is 1.8 x 10^-5, what does this indicate about the strength of acetic acid?
A.
It is a strong acid.
B.
It is a weak acid.
C.
It is a neutral acid.
D.
It completely dissociates in water.
Show Answer & Explanation
Correct Answer: B
A low equilibrium constant (Ka = 1.8 x 10^-5) indicates that acetic acid does not dissociate completely in solution, classifying it as a weak acid.
Q4
Medium
In a dynamic equilibrium, which statement best describes the concentrations of reactants and products?
A.
The concentrations of reactants and products are equal.
B.
The concentrations of reactants and products remain constant.
C.
The concentrations of reactants decrease while products increase continually.
D.
The concentrations of reactants increase while products decrease continually.
Show Answer & Explanation
Correct Answer: B
In a dynamic equilibrium, reactants and products are formed at the same rate, leading to constant concentrations over time.
Q5
Medium
For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the concentration of ammonia is increased, what will be the immediate effect on the system?
A.
Forward reaction rate increases.
B.
Reverse reaction rate increases.
C.
Total pressure of the system increases.
D.
Reaction will cease immediately.
Show Answer & Explanation
Correct Answer: B
According to Le Chatelier's principle, increasing the concentration of a product (NH3) will shift the equilibrium to the left, increasing the reverse reaction.
Q6
Medium
A reaction has an equilibrium constant Kc = 4.0 at 300 K. If the initial concentrations of reactants are [A] = 1.0 M and [B] = 2.0 M, what is the concentration of product C at equilibrium?
A.
0.5 M
B.
1.0 M
C.
2.0 M
D.
4.0 M
Show Answer & Explanation
Correct Answer: B
At equilibrium, Kc = [C]^2 / ([A][B]). By substituting values and solving, we find [C] = 1.0 M.
Q7
Medium
Which factor will NOT affect the position of equilibrium in an exothermic reaction?
A.
Increasing the pressure.
B.
Adding a catalyst.
C.
Decreasing the temperature.
D.
Increasing the concentration of reactants.
Show Answer & Explanation
Correct Answer: B
Adding a catalyst speeds up both forward and reverse reactions equally, thus it does not affect the position of equilibrium.
Q8
Hard
For the equilibrium reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the concentration of NH3 is increased, which of the following will occur to restore equilibrium?
A.
The concentration of N2 will increase.
B.
The concentration of H2 will decrease.
C.
The forward reaction rate will decrease.
D.
The equilibrium will shift to the left.
Show Answer & Explanation
Correct Answer: D
According to Le Chatelier's principle, increasing the concentration of a product (NH3) will shift the equilibrium to the left to consume some of the added product and create more reactants (N2 and H2).
Q9
Hard
Consider the following equilibrium reaction: N2(g) + 3H2(g) ⇌ 2NH3(g). If the initial concentrations are [N2] = 0.5 M, [H2] = 1.5 M, and [NH3] = 0 M, what will be the equilibrium concentration of NH3 if Kc for the reaction is 6.0 at a given temperature?
A.
0.6 M
B.
0.5 M
C.
0.8 M
D.
1.0 M
Show Answer & Explanation
Correct Answer: A
Using the ICE table and the expression for Kc, we find that at equilibrium, the concentration of NH3 is 0.6 M.
Q10
Hard
A system at equilibrium contains 2 moles of A(g), 3 moles of B(g), and 1 mole of C(g) at a total volume of 10 L. The reaction is given by A(g) + B(g) ⇌ 2C(g). What is the equilibrium constant Kp for this reaction at the given conditions?
A.
0.03
B.
0.10
C.
0.20
D.
0.15
Show Answer & Explanation
Correct Answer: B
Calculating Kp involves finding the partial pressures of the reactants and products. The Kp evaluates to 0.10 based on the mole ratios.
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Equilibrium — IB (International Baccalaureate) IB Chemistry HL Practice Questions Online
This page contains 150 practice MCQs for the chapter Equilibrium in IB (International Baccalaureate) IB Chemistry HL. The questions are organized by difficulty — 47 easy, 78 medium, 25 hard — so you can choose the right level for your preparation.
Every question includes a detailed explanation to help you understand the concept, not just memorize answers. Take a timed quiz to simulate exam conditions, or practice at your own pace with no time limit.