Chemical Equilibrium Practice Questions
WAEC (West Africa) · WAEC Chemistry · 147 free MCQs with instant results and detailed explanations.
147
Total
43
Easy
74
Medium
30
Hard
Start Practicing Chemical Equilibrium
Take a timed quiz or customize your practice session
Sample Questions from Chemical Equilibrium
Here are 10 sample questions. Start a quiz to get randomized questions with scoring.
Q1
Easy
What is the principle that states that if a system at equilibrium is disturbed, the system will adjust to counteract the disturbance?
A.
Boyle's Law
B.
Le Chatelier's Principle
C.
Avogadro's Principle
D.
Dalton's Law
Show Answer & Explanation
Correct Answer: B
Le Chatelier's Principle states that if an equilibrium system is subjected to a change in concentration, temperature, or pressure, the system will shift in a direction that counteracts the change, thus establishing a new equilibrium.
Q2
Easy
In a closed container, the reaction A(g) ⇌ B(g) is at equilibrium. If the volume of the container is increased, what will happen to the position of the equilibrium?
A.
Shift to the left
B.
Shift to the right
C.
No change
D.
Become unstable
Show Answer & Explanation
Correct Answer: B
According to Le Chatelier's Principle, increasing the volume of the container decreases the pressure. The equilibrium will shift toward the side with more moles of gas, which in this case is B(g), leading to a shift to the right.
Q3
Easy
If the equilibrium constant Kc for the reaction H2(g) + I2(g) ⇌ 2HI(g) is 50 at a certain temperature, which of the following statements is TRUE about the reaction at equilibrium?
A.
The concentration of HI is low.
B.
The reaction favors the formation of H2 and I2.
C.
The concentration of H2 and I2 is equal to HI.
D.
The formation of HI is favored at this temperature.
Show Answer & Explanation
Correct Answer: D
A high equilibrium constant (Kc = 50) indicates that at equilibrium, the concentration of the products (HI) is much greater than that of the reactants (H2 and I2), thus favoring the formation of HI.
Q4
Medium
What is the effect of increasing temperature on the equilibrium of an exothermic reaction?
A.
The equilibrium shifts to the left.
B.
The equilibrium shifts to the right.
C.
The equilibrium remains unchanged.
D.
The reaction rate decreases.
Show Answer & Explanation
Correct Answer: A
According to Le Chatelier's principle, increasing the temperature of an exothermic reaction causes the equilibrium to shift towards the reactants (left) to absorb the excess heat.
Q5
Medium
In the equilibrium reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the concentration of NH3 is doubled, what will happen to the concentrations of N2 and H2 at equilibrium?
A.
Both N2 and H2 will decrease.
B.
Both N2 and H2 will increase.
C.
N2 will increase, H2 will decrease.
D.
N2 will decrease, H2 will remain constant.
Show Answer & Explanation
Correct Answer: A
Doubling the concentration of NH3 will shift the equilibrium to the left (towards the reactants), causing the concentrations of N2 and H2 to decrease.
Q6
Medium
For the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), if the pressure is increased, what will be the effect on the position of equilibrium?
A.
Equilibrium shifts to form more SO2 and O2.
B.
Equilibrium shifts to form more SO3.
C.
No effect on equilibrium.
D.
Equilibrium shifts to increase the total number of moles.
Show Answer & Explanation
Correct Answer: B
Increasing pressure shifts the equilibrium towards the side with fewer moles of gas. In this case, there are 3 moles of reactants and 2 moles of products, so it shifts to the right to form more SO3.
Q7
Medium
Which of the following statements about dynamic equilibrium is correct?
A.
The rates of forward and reverse reactions are equal.
B.
The concentrations of reactants and products are equal.
C.
The system remains static and unchanging.
D.
The temperature of the system must be constant.
Show Answer & Explanation
Correct Answer: A
In dynamic equilibrium, the rates of the forward and reverse reactions are equal, leading to constant concentrations of reactants and products, despite ongoing reactions.
Q8
Hard
In a reaction at equilibrium, if the concentration of the reactants is increased, which of the following statements is true regarding the effect on the equilibrium position?
A.
The equilibrium shifts to the right, favoring product formation.
B.
The equilibrium shifts to the left, favoring reactant formation.
C.
The equilibrium remains unchanged regardless of reactant concentration.
D.
The equilibrium can shift in either direction, depending on temperature.
Show Answer & Explanation
Correct Answer: A
According to Le Chatelier's Principle, increasing the concentration of reactants will cause the equilibrium to shift towards the products to counteract the change, resulting in more product formation.
Q9
Hard
Given the equilibrium reaction: N2(g) + 3H2(g) ⇌ 2NH3(g), if the temperature of the system is increased, what will be the effect on the yield of NH3 at equilibrium, assuming the reaction is exothermic?
A.
The yield of NH3 will increase.
B.
The yield of NH3 will decrease.
C.
The yield of NH3 will remain constant.
D.
The yield cannot be determined without pressure changes.
Show Answer & Explanation
Correct Answer: B
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left (towards the reactants) according to Le Chatelier's Principle, thus decreasing the yield of NH3.
Q10
Hard
Consider the following equilibrium reaction: N2(g) + 3H2(g) ⇌ 2NH3(g). If the concentration of NH3 is increased, what will be the effect on the equilibrium according to Le Chatelier's Principle?
A.
The equilibrium will shift to the right.
B.
The equilibrium will shift to the left.
C.
There will be no effect on the equilibrium.
D.
The reaction will cease to occur.
Show Answer & Explanation
Correct Answer: B
According to Le Chatelier's Principle, if the concentration of a product (NH3) is increased, the equilibrium will shift to the left to counteract this change, thereby reducing the concentration of NH3.
Showing 10 of 147 questions. Start a quiz to practice all questions with scoring and timer.
Practice All 147 Questions →Other WAEC (West Africa) Subjects
Chemical Equilibrium — WAEC (West Africa) WAEC Chemistry Practice Questions Online
This page contains 147 practice MCQs for the chapter Chemical Equilibrium in WAEC (West Africa) WAEC Chemistry. The questions are organized by difficulty — 43 easy, 74 medium, 30 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.