The rate of the forward reaction decreases with time due to two key factors:
- Decreasing reactant concentration: As the reaction proceeds, the concentration of the reactants decreases, resulting in fewer collisions between reactant molecules and a lower likelihood of successful collisions, reducing the rate of the forward reaction.
- Increasing product concentration: As the forward reaction progresses, the concentration of products increases. This increase in product concentration creates a higher likelihood of product molecules colliding and undergoing the reverse reaction, leading to a decrease in the net forward reaction rate over time.