10 Questions
What is the state in which both the reactants and products are present in concentrations that have no further tendency to change with time?
Dynamic equilibrium
When does the state of chemical equilibrium occur?
When the forward reaction proceeds at the same rate as the reverse reaction
What must be true for a reaction mixture to exist at equilibrium?
The rates of the forward and backward reactions must be equal
What does it mean when the equilibrium concentration position of a reaction is said to lie 'far to the right'?
Nearly all the reactants are consumed
Who developed the concept of chemical equilibrium in 1803?
Berthollet
According to Guldberg and Waage, the law of mass action states that:
The rate constants for the forward and backward reactions are equal at equilibrium.
Why is the law of mass action not valid in general?
It does not consider the stoichiometry of the reaction.
How does the addition of a catalyst affect the equilibrium constant?
It has no effect on the equilibrium constant.
What is observed about macroscopic equilibrium concentrations over time?
They remain constant in time.
In the case of acetic acid dissolved in water and forming acetate and hydronium ions, the process can be described as:
A reversible reaction.
Study Notes
Chemical Equilibrium
- Chemical equilibrium is the state in which both the reactants and products are present in concentrations that have no further tendency to change with time.
Conditions for Equilibrium
- The state of chemical equilibrium occurs when the rates of forward and reverse reactions are equal.
- For a reaction mixture to exist at equilibrium, the Gibbs free energy change (ΔG) must be zero.
Equilibrium Concentration Position
- When the equilibrium concentration position of a reaction is said to lie 'far to the right', it means that the reaction has a high yield of products.
History of Chemical Equilibrium
- The concept of chemical equilibrium was developed by Claude-Louis Berthollet in 1803.
The Law of Mass Action
- According to Guldberg and Waage, the law of mass action states that at equilibrium, the ratio of the concentrations of products to the concentrations of reactants is constant for a given temperature.
- The law of mass action is not valid in general due to the presence of external influences such as temperature and pressure.
Effect of Catalysts on Equilibrium
- The addition of a catalyst does not affect the equilibrium constant, but it does increase the rate at which equilibrium is achieved.
Macroscopic Equilibrium Concentrations
- Over time, macroscopic equilibrium concentrations appear to be constant.
Acid-Base Equilibrium
- The dissociation of acetic acid in water to form acetate and hydronium ions is an example of acid-base equilibrium.
Test your knowledge of chemical equilibrium with this quiz. Assess your understanding of the state where the concentrations of reactants and products remain constant over time due to equal forward and reverse reaction rates.
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