Introduction:
According to simple collision theory, the rate of a chemical reaction depends on the number of successful collisions between reactant molecules. The theory states that for a reaction to occur, the reacting molecules must collide with sufficient energy and with proper orientation. Increasing the temperature affects the rate of reaction by altering the number of collisions that meet these criteria.

Effect of temperature on collision rate:
When the temperature is increased, the average kinetic energy of the molecules also increases. This leads to an increase in the speed at which the molecules move. As a result, the frequency of collisions between reactant molecules increases.

Increase in the number of collisions:
1. Increased molecular motion: With an increase in temperature, the molecules move faster and collide more frequently. This increases the number of collisions.

2. Higher collision energy: The increased temperature also leads to an increase in the average kinetic energy of the molecules. This means that the collisions occur with greater energy, increasing the chances of successful collisions.

3. Enhanced collision frequency: The collision frequency is directly proportional to the product of the concentrations of the reactants. As the temperature increases, the reaction rate increases, which implies that the concentration of reactants decreases over time. However, the increase in collision frequency due to the higher molecular motion compensates for the decrease in reactant concentration.

Collision frequency equation:
The rate of reaction is directly proportional to the collision frequency between reactant molecules. Mathematically, the collision frequency can be expressed as:

Collision frequency = Z * f * P

Where:
- Z represents the total number of collisions per unit time.
- f represents the fraction of collisions that are effective (have sufficient energy and proper orientation).
- P represents the probability factor, which depends on the steric effects and molecular geometry.

Conclusion:
In conclusion, when the temperature is increased from 800K to 1320K, the number of collisions between reactant molecules will increase. This is due to the increased molecular motion, higher collision energy, and enhanced collision frequency. These factors result in a higher collision rate, leading to an increase in the rate of reaction.