#1
Which statement describes chemical equilibrium?
The rate of the forward reaction is equal to the rate of the reverse reaction.
ExplanationEquilibrium is achieved when the rates of the forward and reverse reactions are equal.
#2
Which statement is true regarding a system at equilibrium?
The concentrations of reactants and products are constant.
ExplanationAt equilibrium, the concentrations of reactants and products remain unchanged over time.
#3
Which statement accurately describes a dynamic equilibrium?
The concentrations of reactants and products remain constant over time.
ExplanationDynamic equilibrium is reached when the rate of the forward reaction equals the rate of the reverse reaction, maintaining constant concentrations.
#4
Which statement accurately describes a homogeneous equilibrium?
All reactants and products are in the same physical state.
ExplanationHomogeneous equilibrium involves reactants and products existing in the same phase.
#5
Which statement accurately describes the reaction quotient Q?
It is calculated using initial concentrations of reactants and products.
ExplanationReaction quotient Q is determined using initial concentrations of reactants and products, regardless of the system's current state.
#6
What does Le Chatelier's Principle state?
When a stress is applied to a system in dynamic equilibrium, the system adjusts to reduce the stress.
ExplanationThe principle explains how systems at equilibrium respond to external changes to maintain equilibrium.
#7
Which factor does NOT affect the position of equilibrium?
Catalyst
ExplanationCatalysts affect reaction rates but not the position of equilibrium.
#8
How does increasing the temperature affect an endothermic reaction at equilibrium?
It shifts the equilibrium towards the products.
ExplanationIncreasing temperature favors the endothermic reaction to absorb heat, shifting equilibrium towards products.
#9
Which of the following statements about the equilibrium constant (Kc) is correct?
Kc is only applicable to homogeneous equilibria.
ExplanationEquilibrium constant (Kc) applies only to reactions where all species are in the same phase.
#10
What happens to the equilibrium position when a catalyst is added to a reaction at equilibrium?
The equilibrium position remains unchanged.
ExplanationCatalysts affect the rate of both forward and reverse reactions equally, leaving the equilibrium position unaffected.
#11
How does increasing the pressure affect the equilibrium position of a reaction involving gaseous reactants and products?
It shifts the equilibrium towards the side with fewer moles of gas.
ExplanationIncreasing pressure shifts equilibrium towards fewer moles of gas to reduce pressure.
#12
How does increasing the concentration of a reactant affect the equilibrium position?
It shifts the equilibrium towards the reactants.
ExplanationAccording to Le Chatelier's principle, increasing reactant concentration shifts equilibrium towards products to counteract the change.
#13
What is the equilibrium constant expression for the reaction: 2A + 3B ⇌ 4C?
[C]^4 / [A]^2[B]^3
ExplanationThe equilibrium constant expression involves the concentrations of products over the concentrations of reactants, each raised to their respective stoichiometric coefficients.
#14
Which statement best describes a heterogeneous equilibrium?
Reactants and products are in different phases.
ExplanationIn a heterogeneous equilibrium, the substances involved exist in different physical states.
#15
What is the effect of adding an inert gas at constant volume to a system at equilibrium?
It has no effect on the equilibrium position.
ExplanationAdding inert gas at constant volume doesn't alter concentrations, hence no effect on equilibrium position.
#16
In the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the volume of the container is decreased, what will happen to the concentration of NH3 at equilibrium?
It will increase.
ExplanationAccording to Le Chatelier's principle, reducing volume shifts equilibrium towards fewer moles, thus increasing NH3 concentration.
#17
For the reaction CO(g) + H2O(g) ⇌ CO2(g) + H2(g), if the concentration of CO2 is increased, what happens to the concentrations of CO and H2O at equilibrium?
CO decreases and H2O increases.
ExplanationIncreasing CO2 concentration shifts equilibrium towards CO2 and H2, hence reducing CO and increasing H2O concentrations.
#18
What is the effect of increasing the volume on a system at equilibrium for a reaction that involves a decrease in the number of moles of gas?
It shifts the equilibrium towards the side with more moles of gas.
ExplanationIncreasing volume decreases pressure, shifting equilibrium towards more moles of gas to counteract the change.
#19
For the reaction N2(g) + 3H2(g) ⇌ 2NH3(g), if the pressure is increased by decreasing the volume, what happens to the concentration of NH3 at equilibrium?
It increases.
ExplanationIncreasing pressure shifts equilibrium towards fewer moles of gas, thus increasing NH3 concentration.