Chemical Equilibrium - SS2 Chemistry Past Questions and Answers - page 1
What is a reversible reaction?
A reaction that only proceeds in one direction
A reaction that proceeds in both forward and reverse directions
A reaction that occurs spontaneously without any reverse reaction
A reaction that cannot reach equilibrium
What is dynamic equilibrium?
A state where the forward reaction has completely stopped
A state where the concentrations of reactants and products are equal
A state where the rate of the forward and reverse reactions are equal
A state where the reaction has reached completion
Which statement is true about a system at dynamic equilibrium?
The concentrations of reactants and products are equal.
The concentrations of reactants and products are zero.
The reaction has stopped and no further changes occur.
The rate of the forward and reverse reactions are equal, but the concentrations may not be equal.
How does increasing the temperature affect a reversible reaction at equilibrium?
It shifts the equilibrium to favour the reactants.
It shifts the equilibrium to favour the products.
It does not affect the equilibrium position.
It causes the reaction to stop completely.
What happens to a reversible reaction system when the concentration of a reactant is increased?
The reaction shifts to consume more reactants and form more products.
The reaction shifts to consume more product and form more reactant.
The reaction remains at equilibrium without any changes.
The reaction stops completely.
Which factor does not affect the position of equilibrium in a reversible reaction?
Temperature
Pressure
Catalyst
Concentration
In a reversible reaction, if the forward reaction is exothermic, what can be said about the reverse reaction?
It is also exothermic.
It is endothermic.
The reverse reaction is not influenced by the forward reaction.
The reverse reaction has no energy change.
What is the condition for a reaction to reach dynamic equilibrium?
The concentration of reactants is greater than the concentration of products.
The rate of the forward reaction is greater than the rate of the reverse reaction.
The concentrations of reactants and products are equal.
The rate of the forward and reverse reactions are equal.
Explain the concept of a reversible reaction and how it differs from an irreversible reaction. Provide examples of both types.
A reversible reaction is a chemical reaction that can proceed in both the forward and reverse directions. It means that products can react with each other to form reactants, and reactants can react to form products. In a reversible reaction, there is an equilibrium state where the concentrations of reactants and products remain constant over time.
On the other hand, an irreversible reaction is a chemical reaction that proceeds in only one direction, and the conversion of reactants into products is complete. The reactants are entirely consumed, and the reaction cannot revert back to the original reactants.
Example of a reversible reaction: The Haber-Bosch process for ammonia synthesis:
N2(g) + 3H2(g) ⇌ 2NH3(g)
In this reaction, nitrogen gas (N2) and hydrogen gas (H2) react to form ammonia gas (NH3). However, ammonia can also decompose back into nitrogen and hydrogen under certain conditions.
Example of an irreversible reaction: Combustion of methane:
CH4(g) + 2O2(g) → CO2(g) + 2H2O(g)
In this reaction, methane gas (CH4) reacts with oxygen gas (O2) to form carbon dioxide (CO2) and water (H2O). The combustion of methane is an irreversible process, and it proceeds in only one direction.
Users' Answers & CommentsDescribe the concept of dynamic equilibrium in reversible reactions. Discuss the conditions required for a system to reach dynamic equilibrium.
Dynamic equilibrium is a state reached in a reversible reaction when the rates of the forward and reverse reactions are equal. In dynamic equilibrium, the concentrations of reactants and products remain constant over time, but the reactions continue to occur simultaneously. It is important to note that dynamic equilibrium does not imply that the reactants and products are present in equal amounts, but rather that their concentrations are stable.
To reach dynamic equilibrium, certain conditions must be met:
a. A closed system: The reaction must occur in a closed system where no reactants or products can enter or leave the system. This ensures that the total amount of matter remains constant throughout the process.
b. Reversible reaction: The reaction must be reversible, meaning it can proceed in both the forward and reverse directions. This allows the establishment of equilibrium between the reactants and products.
c. Constant temperature: The reaction must occur at a constant temperature. Temperature affects the rates of the forward and reverse reactions, and a stable temperature ensures that the rates remain equal at equilibrium.
d. Sufficient time: The system needs sufficient time for the forward and reverse reactions to establish equilibrium. The rate at which equilibrium is reached depends on the reaction kinetics and the complexity of the reaction.
When a system reaches dynamic equilibrium, the concentrations of reactants and products no longer change, but the reactions continue to occur. At equilibrium, the forward and reverse reactions are balanced, maintaining a constant ratio between the concentrations of reactants and products.
Users' Answers & Comments