Explain how and why the rate of a reaction changes. Use ideas about the collisions between particles.
The effect of collisions between particles on reaction rate is described by collision theory. According to collision theory, a reaction can only occur if the reactant particles are able to collide with one another. Anything that increases the probability that the reactant particles will collide, also increases the rate of the reaction.
Temperature and Particle Collision
When the reactants are heated, the reactant particles move faster. This makes it more likely that they will collide with one another and react.
Catalysts and Particle Collision
A catalyst provides an alternate route for a reaction occur. As particles gather on the surface of the catalyst, they are able to collide more frequently and the reaction rate increases.
Surface Area and Particle Collision
The greater the surface area of the reactant particles, the more likely they will collide and react. The surface area of a reactant can be increased by breaking it into smaller pieces.
Concentration and Particle Collision
For many reactions, increasing the concentration of the reactant particles increases the reaction rate. The more reactant particles that are present, the more likely it is that they will collide and react.