Q. If the temperature of an exothermic reaction at equilibrium is increased, what will be the effect on the equilibrium position?
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 is the effect of decreasing the volume of the container?
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 position
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 when the temperature is decreased?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the reaction rate
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 reaction CO(g) + 2H2(g) ⇌ CH3OH(g), what is the effect of increasing the pressure?
A.
Shifts to the right
B.
Shifts to the left
C.
No effect
D.
Increases the temperature
Solution
Increasing the pressure favors the side with fewer moles of gas. In this case, the right side has fewer moles (1 mole of CH3OH) compared to the left (3 moles), so the equilibrium shifts to the right.
