Question

With regard to concentration, what is characteristic of a reversible reaction at equilibrium?

Short answer

At equilibrium, the concentrations of reactants and products remain constant but not necessarily equal.

Step-by-step solution

Understanding Reversible Reactions

A reversible reaction is one where the reactants can form products, which can also revert back to the original reactants. This means both the forward and the reverse reactions are occurring simultaneously.

Defining Chemical Equilibrium

Chemical equilibrium in a reversible reaction occurs when the forward and reverse reactions proceed at the same rate. This results in no net change in the concentrations of reactants and products over time.

Analyzing Concentration at Equilibrium

At equilibrium, the concentrations of reactants and products remain constant. This does not imply they are equal, just that their concentrations have stabilized and will not change as long as the system remains undisturbed.

Key concepts

Reversible Reactions

Reversible reactions are fascinating because they can proceed in both directions. This means that the reactants can transform into products, and those products can transform back into the initial reactants. This dynamic relationship is represented as:

• Reactants ⇌ Products

The double arrow indicates that both the forward and reverse reactions are possible. In a closed system, these reactions continue to occur until they reach a balance, known as equilibrium. It is important to note that reversible reactions can be influenced by factors such as temperature and pressure which can shift the balance between products and reactants. At any given point before equilibrium, the direction with the faster reaction rate will dominate, leading to higher concentrations of either reactants or products.

Concentration at Equilibrium

At chemical equilibrium, the remarkable feature is that the concentrations of both reactants and products remain constant over time. This does not mean that the concentrations are equal, just that they do not change unless the system is disturbed. For instance, adding more reactants or changing the temperature can drive the reaction forward or backward.

• Equilibrium concentrations depend on the specific reaction and conditions like temperature and pressure.
• Even though the concentrations don't change at equilibrium, molecules are still reacting with each other; they do so at the same rate for both directions.

Equilibrium is dynamic. This means that, at the molecular level, reactions continue to occur, but because they happen at equal rates, there's no overall change. This delicate balance is key to many metabolic and industrial processes that rely on specific concentration levels of chemicals.

Forward and Reverse Reactions

In a reversible reaction, both the forward and reverse reactions occur simultaneously. The forward reaction is when reactants form products, while the reverse reaction is when those products revert to reactants. At equilibrium, these reactions happen at the same rate, meaning that for every molecule of reactant that turns into a product, a product molecule turns back into a reactant. Understanding the rates of these reactions is essential for influencing chemical processes:

• If the forward reaction rate is higher, the system will shift to produce more products.
• If the reverse reaction rate is higher, the system will result in more reactants.

Reactions can be manipulated by changing certain conditions, such as temperature or concentration, to favor either the forward or reverse reaction. This concept is utilized in industrial chemical production to maximize yields and control product formation. Knowing how to influence these rates effectively can lead to successful applications in fields like pharmaceuticals and energy production.