Chemistry - Chemical Equilibrium - MCQs
Learn about the dynamic state of reversible reactions and factors affecting chemical equilibrium.
Which of the following best describes a system at equilibrium?
A. No reactions are occurring
B. The rates of the forward and reverse reactions are equal
C. Reactants are fully converted to products
D. Only the forward reaction is occurring
Answer: The rates of the forward and reverse reactions are equal
In which of the following cases does pressure have the most significant effect on equilibrium?
A. Reactions involving only solids
B. Reactions involving gases
C. Reactions involving liquids
D. Reactions in solution
Answer: Reactions involving gases
What happens to a reaction’s equilibrium when a reactant is removed from the system?
A. Equilibrium shifts to the right
B. Equilibrium shifts to the left
C. No change
D. The reaction rate increases
Answer: Equilibrium shifts to the left
What is the effect of increasing pressure on a reaction where the number of gas molecules is the same on both sides?
A. Shifts the equilibrium to the right
B. Shifts the equilibrium to the left
C. No change
D. The reaction rate increases
Answer: No change
What is meant by the term ‘dynamic equilibrium’ in chemistry?
A. The reaction has stopped
B. The forward and reverse reactions occur at the same rate
C. The concentrations of products are higher than reactants
D. The rate of the forward reaction is greater than the reverse reaction
Answer: The forward and reverse reactions occur at the same rate
In the reaction CO(g) + H2O(g) ⇌ CO2(g) + H2(g), what happens if CO2 is removed?
A. Equilibrium shifts to the left
B. Equilibrium shifts to the right
C. No effect
D. The reaction stops
Answer: Equilibrium shifts to the right
Which factor affects the value of the equilibrium constant (Kc) for a reaction?
A. Concentration
B. Pressure
C. Temperature
D. Catalyst
Answer: Temperature
In a reversible reaction, what does the equilibrium constant (K) represent?
A. The ratio of the concentrations of reactants to products
B. The ratio of the forward reaction rate to the reverse reaction rate
C. The difference in energy between reactants and products
D. The overall reaction rate
Answer: The ratio of the forward reaction rate to the reverse reaction rate
What is true of a reaction at dynamic equilibrium?
A. No reaction occurs
B. The forward and reverse reactions occur at the same rate
C. The forward reaction stops
D. The reverse reaction is faster than the forward reaction
Answer: The forward and reverse reactions occur at the same rate
What is the effect of increasing the concentration of products in a reversible reaction at equilibrium?
A. Shifts the equilibrium to the right
B. Shifts the equilibrium to the left
C. No effect
D. Decreases the reaction rate
Answer: Shifts the equilibrium to the left