Chemical Equilibrium - SS2 Chemistry Past Questions and Answers - page 2
When a system at equilibrium is subjected to an increase in temperature, what will happen to the equilibrium position?
The equilibrium position will shift towards the reactants.
The equilibrium position will shift towards the products.
The equilibrium position will remain unchanged.
It depends on the specific reaction.
When the pressure is increased in a system at equilibrium involving gaseous reactants and products, what effect will it have on the equilibrium position?
The equilibrium position will shift towards the reactants.
The equilibrium position will shift towards the products.
The equilibrium position will remain unchanged.
It depends on the specific reaction.
If the concentration of a reactant is increased in a system at equilibrium, how will it affect the equilibrium position?
The equilibrium position will shift towards the reactants.
The equilibrium position will shift towards the products.
The equilibrium position will remain unchanged.
It depends on the specific reaction.
In a reaction where the number of moles of gaseous reactants is greater than the number of moles of gaseous products, what will happen to the equilibrium position when the volume of the container is increased?
The equilibrium position will shift towards the reactants.
The equilibrium position will shift towards the products.
The equilibrium position will remain unchanged.
It depends on the specific reaction.
If a catalyst is added to a reaction at equilibrium, what effect will it have on the equilibrium position?
The equilibrium position will shift towards the reactants.
The equilibrium position will shift towards the products.
The equilibrium position will remain unchanged.
It depends on the specific reaction.
Explain Le Chatelier's Principle and its application to chemical equilibrium. Provide examples to illustrate its effect on equilibrium systems.
Le Chatelier's Principle states that when a system in equilibrium is subjected to a change in conditions, the system will adjust to counteract the change and establish a new equilibrium. It helps predict the direction in which an equilibrium system will shift when changes are imposed on it.
Le Chatelier's Principle can be applied to changes in temperature, pressure, and concentration to understand the effect on equilibrium systems. Here are a few examples:
a. Temperature Change: When the temperature of an equilibrium system is increased, the system will shift in the direction that absorbs heat (endothermic reaction). Conversely, if the temperature is decreased, the system will shift in the direction that releases heat (exothermic reaction). For example, in the Haber-Bosch process for ammonia synthesis, increasing the temperature decreases the yield of ammonia (NH3) because the reaction is exothermic.
b. Pressure Change: Changes in pressure affect equilibrium systems involving gases. An increase in pressure will cause the system to shift in the direction that reduces the number of moles of gas, while a decrease in pressure will cause the system to shift in the direction that increases the number of moles of gas. For instance, in the reaction between nitrogen dioxide (NO2) and dinitrogen tetroxide (N2O4), increasing the pressure favours the formation of N2O4 since it has fewer gas molecules.
2NO2(g) ⇌ N2O4(g)
c. Concentration Change: Altering the concentration of reactants or products can influence equilibrium. If more reactants are added, the system will shift in the direction that consumes the added reactants. Conversely, if more products are added, the system will shift in the direction that consumes the added products. For example, in the equilibrium between carbon monoxide (CO) and hydrogen gas (H2) in the synthesis of methanol, adding more CO will cause the system to shift towards the production of methanol.
CO(g) + 2H2(g) ⇌ CH3OH(g)
Le Chatelier's Principle provides a useful framework for predicting and understanding the response of equilibrium systems to changes in temperature, pressure, and concentration. It helps in optimising reaction conditions to maximise desired products or yield. By applying Le Chatelier's Principle, scientists and engineers can manipulate equilibrium systems to enhance efficiency and desired outcomes in various chemical processes.
What is the equilibrium constant, Kc, for the balanced equation below? 2A + 3B ⇌ C + D
Kc = [C][D] / [A]2[B]3
Kc = [A]2[B]3 / [C][D]
Kc = [A][B] / [C][D]
Kc = [C][D] / [A][B]
Which of the following statements about equilibrium constants is correct?
The equilibrium constant (Kc or Kp) depends on the initial concentrations of the reactants and products.
The equilibrium constant (Kc or Kp) is influenced by the reaction rate.
.
The equilibrium constant (Kc or Kp) remains constant at a given temperature.
The equilibrium constant (Kc or Kp) changes with changes in pressure
The equilibrium constant, Kp, is used when:
The concentrations of reactants and products are given.
The reaction takes place in a closed system at constant pressure.
The reaction involves only gases.
The reaction involves both gases and solids.
Which of the following represents the correct expression for the equilibrium constant, Kp?
Kp = [A][B] / [C][D]
Kp = (P[A])2(P[B])3 / (P[C])(P[D])
Kp = (P[C])(P[D]) / (P[A])(P[B])
Kp = (P[A])(P[B]) / (P[C])(P[D])