Q. If the temperature of an exothermic reaction at equilibrium is increased, what will happen to the equilibrium position?
A.
Shift to the right
B.
Shift to the left
C.
No change
D.
Reaction rate increases
Solution
For an exothermic reaction, increasing the temperature shifts the equilibrium to the left, favoring the reactants, as the system tries to absorb the added heat.
Q. In a reaction at equilibrium, what happens if the pressure is increased by decreasing the volume?
A.
Shifts to the side with more moles of gas
B.
Shifts to the side with fewer moles of gas
C.
No effect
D.
Reaction stops
Solution
Increasing the pressure by decreasing the volume shifts the equilibrium towards the side with fewer moles of gas, according to Le Chatelier's Principle.
Correct Answer:
B
— Shifts to the side with fewer moles of gas
Q. In a reaction where heat is absorbed (endothermic), what is the effect of increasing temperature?
A.
Shifts equilibrium to the right
B.
Shifts equilibrium to the left
C.
No effect
D.
Decreases reaction rate
Solution
Increasing the temperature in an endothermic reaction shifts the equilibrium to the right, favoring the formation of products as the system absorbs the added heat.
Correct Answer:
A
— Shifts equilibrium to the right
Q. In the reaction A(g) + B(g) ⇌ C(g), if the pressure is increased, which direction will the equilibrium shift if there are more moles of gas on the left?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases temperature
Solution
Increasing pressure will shift the equilibrium to the right, favoring the side with fewer moles of gas.
Q. What effect does adding an inert gas at constant volume have on the equilibrium of a reaction?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the rate of reaction
Solution
Adding an inert gas at constant volume does not change the partial pressures of the reactants or products, thus it has no effect on the equilibrium position.
Q. What happens to the equilibrium position when the concentration of a reactant is increased?
A.
The equilibrium shifts to the right
B.
The equilibrium shifts to the left
C.
No change occurs
D.
The reaction stops
Solution
According to Le Chatelier's Principle, increasing the concentration of a reactant will shift the equilibrium position to the right to favor the formation of products.
Correct Answer:
A
— The equilibrium shifts to the right
Q. What happens to the position of equilibrium when the concentration of a reactant is increased?
A.
The equilibrium shifts to the right
B.
The equilibrium shifts to the left
C.
No change occurs
D.
The reaction stops
Solution
According to Le Chatelier's Principle, increasing the concentration of a reactant will shift the equilibrium position to the right to favor the formation of products.
Correct Answer:
A
— The equilibrium shifts to the right
Q. What is the effect of a catalyst on a system at equilibrium?
A.
Shifts the equilibrium position
B.
Increases the rate of reaction
C.
Decreases the equilibrium constant
D.
Has no effect on the reaction
Solution
A catalyst increases the rate of both the forward and reverse reactions equally, thus it does not shift the equilibrium position but helps reach it faster.
Correct Answer:
B
— Increases the rate of reaction
Q. What is the effect of increasing the concentration of a product in a reaction at equilibrium?
A.
Shifts equilibrium to the right
B.
Shifts equilibrium to the left
C.
No change occurs
D.
Increases reaction rate
Solution
Increasing the concentration of a product will shift the equilibrium to the left, favoring the formation of reactants, according to Le Chatelier's Principle.
Correct Answer:
B
— Shifts equilibrium to the left
