The main drawback of the Collision theory is that it considers atoms and molecules to be hard spheres and ignores their structures. It does not provide any prediction of p, the “steric factor”, calculated values for the rate constant are usually too high compared with measured values .

Reactions require an input of energy to initiate the reaction; this is called the activation energy (EA). Activation energy is the amount of energy required to reach the transition state. The source of the activation energy needed to push reactions forward is typically heat energy from the surroundings.

The following are the drawbacks of collision theory.

• This theory does not advance any explanation for the abnormally high rates that are observed sometimes.
• This theory cannot be applied to reversible reactions with complete success.

Collision theory states that the rate of a chemical reaction is proportional to the number of collisions between reactant molecules. The more often reactant molecules collide, the more often they react with one another, and the faster the reaction rate. Effective collisions are those that result in a chemical reaction.

Collision theory explains why most reaction rates increase as concentrations increase. With an increase in the concentration of any reacting substance, the chances for collisions between molecules are increased because there are more molecules per unit of volume.

Collision theory states that for a chemical reaction to occur, the reacting particles must collide with one another. The rate of the reaction depends on the frequency of collisions. The theory also tells us that reacting particles often collide without reacting.

Molecules must collide with sufficient energy, known as the activation energy, so that chemical bonds can break. Molecules must collide with the proper orientation. A collision that meets these two criteria, and that results in a chemical reaction, is known as a successful collision or an effective collision.

For a chemical reaction to happen: reactant particles must collide with each other. the particles must have enough energy for them to react.

Collision Theory states that in order for a reaction to proceed, the reactant particles must collide. (a) collide with sufficient energy to break any bonds in the reactant particles. The activation energy is the minimum amount of energy the colliding reactant particles must have in order for products to form.

Increasing the temperature increases reaction rates because of the disproportionately large increase in the number of high energy collisions. It is only these collisions (possessing at least the activation energy for the reaction) which result in a reaction.

Changing temperature Increasing the temperature decreases the value of the equilibrium constant. Where the forward reaction is endothermic, increasing the temperature increases the value of the equilibrium constant. The position of equilibrium also changes if you change the temperature.