Q. If the temperature of an exothermic reaction at equilibrium is increased, what will happen?
A.
The equilibrium shifts to the right
B.
The equilibrium shifts to the left
C.
No change occurs
D.
The 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.
Correct Answer:
B
— The equilibrium shifts to the left
Q. If the temperature of an exothermic reaction is increased, what is the expected effect on the equilibrium?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
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 effect does adding an inert gas at constant volume have?
A.
Shifts the equilibrium to the right
B.
Shifts the equilibrium to the left
C.
No effect on the equilibrium
D.
Increases the reaction rate
Solution
Adding an inert gas at constant volume does not change the partial pressures of the reactants or products, thus having no effect on the equilibrium position.
Q. In a reaction at equilibrium, what is the effect of decreasing the volume of the system?
A.
Shifts the equilibrium to the side with more moles of gas
B.
Shifts the equilibrium to the side with fewer moles of gas
C.
No effect on the equilibrium
D.
Increases the temperature
Solution
Decreasing the volume increases the pressure, and according to Le Chatelier's Principle, the equilibrium will shift to the side with fewer moles of gas to counteract the change.
Correct Answer:
B
— Shifts the equilibrium to the side with fewer moles of gas
Q. In a reaction where heat is absorbed (endothermic), what happens if the temperature is decreased?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Reaction rate decreases
Solution
Decreasing the temperature in an endothermic reaction shifts the equilibrium to the left, favoring the formation of reactants as the system seeks to release heat.
Q. In the equilibrium reaction A(g) + B(g) ⇌ C(g), if the volume is increased, what will happen?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the concentration of C
Solution
Increasing the volume decreases the pressure, and according to Le Chatelier's Principle, the equilibrium will shift to the right to favor the formation of more gas molecules (C).
Q. In the reaction 2SO2(g) + O2(g) ⇌ 2SO3(g), what will happen if the pressure is increased?
A.
Shifts to the left
B.
Shifts to the right
C.
No effect
D.
Increases the temperature
Solution
Increasing the pressure will shift the equilibrium to the right, favoring the formation of SO3, as it has fewer moles of gas (2 moles) compared to the reactants (3 moles).
Q. What is the effect of decreasing the volume of a gaseous reaction mixture at equilibrium?
A.
Shifts to the side with more moles of gas
B.
Shifts to the side with fewer moles of gas
C.
No effect
D.
Increases the temperature
Solution
Decreasing the volume increases the pressure, and according to Le Chatelier's Principle, the equilibrium will shift to the side with fewer moles of gas to counteract the change.
Correct Answer:
B
— Shifts to the side with fewer moles of gas
