Products of an Equilibrium Reaction with Time

Introduction

• In a chemical reaction, the concentrations of reactants and products can change over time.
• This change in concentrations reflects the progress of the reaction from its initial state to a state of equilibrium.

Initial State

• At the start of the reaction, the concentrations of reactants are at their maximum, and there are no products formed.
• This is represented as 100% reactants.

Progress of the Reaction

• As the reaction proceeds, reactants are consumed, and products are formed.
• The concentrations of reactants gradually decrease, while the concentrations of products increase.
• This change continues until the reaction reaches equilibrium.

Equilibrium State

• At equilibrium, the concentrations of both reactants and products remain constant.
• This means that the forward and reverse reactions are occurring at the same rate, leading to a dynamic balance.
• Equilibrium is not a static state but rather a dynamic one where reactants are still converting into products and vice versa.

Representing Equilibrium

• The progress of a reversible reaction can be represented graphically.
• Initially, the concentration of reactants is high, and the concentration of products is low.
• As the reaction proceeds, the concentration of reactants decreases, and the concentration of products increases.

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Products of an Equilibrium Reaction with Time

• When the graph levels off, it indicates that the reaction has reached equilibrium.
• The flat portion of the graph at equilibrium signifies that the concentrations of both reactants and products remain constant over time.

Example: Water Dissociation

• In the dissociation of water into ions:
  • H2O(l) ⇌ H⁺(aq) + OH⁻(aq)
• Initially, there are mainly water molecules.
• As the reaction proceeds, some water molecules dissociate into ions.
• At equilibrium, there is a dynamic balance between the concentrations of water molecules, H⁺ ions, and OH⁻ ions.

Conclusion

• The concentrations of reactants and products in a chemical reaction change with time until equilibrium is reached.
• At equilibrium, the concentrations remain constant, indicating a dynamic balance between the forward and reverse reactions.