A-level Chemistry: Collision Theory And The Rate Of A Chemical Reaction.

In the collision theory, the rate of a chemical reaction is determined by the frequency of effective collisions between reactant particles. Effective collisions are those that have sufficient energy and proper orientation to result in a successful reaction.

To understand how increasing temperature affects the rate of a reaction, we can plot a graph of (1/t) against the average temperature, where "t" represents the time taken for a reaction to occur.

Let`s assume we have two sets of reactions: one at a lower temperature (T1) and another at a higher temperature (T2). The x-axis represents the average temperature, while the y-axis represents the reciprocal of the time taken for the reaction to occur.

As the temperature increases, the graph of (1/t) against temperature would generally exhibit the following characteristics:

Decreasing Curve: Initially, at lower temperatures, the time taken for the reaction to occur is longer, resulting in a smaller value for (1/t). As a result, the graph starts with a higher value and gradually decreases as temperature increases.

Steepening Slope: As the temperature increases, the rate of increase in (1/t) becomes more pronounced. This is because higher temperatures provide reactant particles with more kinetic energy, leading to an increased collision frequency.

Asymptote: The graph approaches a horizontal asymptote as the temperature reaches very high values. This is because at extremely high temperatures, the reaction rate approaches its maximum limit, governed by factors such as catalyst activity or equilibrium constraints.

So, based on the collision theory, we can conclude the following:

Increasing the temperature increases the average kinetic energy of the reactant particles. As a result, they move faster and collide more frequently.

Higher temperatures also increase the proportion of reactant particles with energy equal to or greater than the activation energy, leading to a greater number of effective collisions.

The steeper slope in the graph indicates that even small temperature increases can have a significant impact on the reaction rate.

However, there is an upper limit to the effect of temperature on reaction rate, as indicated by the asymptote. This is because other factors, such as catalysts or equilibrium constraints, may come into play at extremely high temperatures.

Overall, the graph of (1/t) against average temperature demonstrates how increasing temperature affects the rate of a reaction according to the collision theory.