Introduces the core concepts of reversible reactions and dynamic equilibrium. This stack covers the foundational ideas that define a system where the rates of forward and reverse reactions are equal, leading to constant macroscopic properties.
A chemical reaction that can proceed in both the forward direction (reactants forming products) and the reverse direction (products reforming reactants).
What is the symbol used to denote a reversible reaction in a chemical equation?
$$
ightleftharpoons $$
Define chemical equilibrium in terms of reaction rates.
Chemical equilibrium is the state in a reversible reaction where the rate of the forward reaction is exactly equal to the rate of the reverse reaction.
What is meant by the term "dynamic" in the phrase "dynamic equilibrium"?
It signifies that at the molecular level, both forward and reverse reactions are continuously occurring. There is constant activity, even though there is no overall change in the concentrations of substances.
Are the concentrations of reactants and products necessarily equal at equilibrium?
No. At equilibrium, the concentrations of reactants and products become constant, but they are rarely equal. Their relative amounts are determined by the equilibrium constant, \(K\).
What happens to observable, macroscopic properties (like color, pressure, or concentration) when a system reaches equilibrium?
All macroscopic properties of the system become constant and no longer change over time.
Why must a system be "closed" to achieve chemical equilibrium?
A closed system prevents the entry or escape of any substances. This is necessary so that the concentrations of reactants and products are solely determined by the forward and reverse reactions within the system.
As a reversible reaction approaches equilibrium from the start, what happens to the rate of the forward reaction?
The forward reaction rate decreases. This is because the concentration of the reactants is continuously being depleted as they are converted into products.
As a reversible reaction approaches equilibrium from the start, what happens to the rate of the reverse reaction?
The reverse reaction rate increases from zero. This is because the concentration of the products builds up from zero, providing more material to react in the reverse direction.
