What is collision theory of reaction rate?

Collision theory is a theory that governs the rate of reaction and states that there must be collisions before reaction will occur.

There is a need to understand that no reaction will occur until there is collisions between reactant particles and only the effective collisions lead to the formation of products.

How does collision theory affect reaction rate?

The reaction of reactants in chemical reaction only occurs when particles collide with each other and if there is no reaction then there will be no reaction.

Terms associated with Collision theory and rates of reaction
Reaction rate: This is the number of products formed per unit time.           
OR            This is the amount of reactants consumed per unit time.           
OR            This is the amount of reactants converted to products per unit time.
Frequency of collision: This is the number of collisions per unit time.
Activation energy: This is the minimum amount of energy that must be equaled or overcome before chemical reactions will take place.
Catalyzed reaction: This is reaction involving a catalyst providing a reduced activation pathway.
Collision theory: This state’s that no reaction will take place until there is collision between the reactant particles and only a fraction of these collisions leads to products. Hint : Not all collisions lead to the formation of products
Effective collision: This is the type of collisions that leads to the formation of products by generating energy equal or more than the activation energy.
Ineffective collisions: This is the type of collisions that do not lead to the formation of products.

Collision theory and rates of reaction

So we can boldly say that the rate of reaction is a function of collision theory because when particles do not collide , then there will be no interaction meaning bonds will not be broken and new bonds will not be formed.

Collision rate which deals with the number of frequency of collision of the particles depends on certain factors like temperature, pressure, concentration which can alter the rate of collision and thus rates of reaction.

Analysis of the collision theory and rates of reaction

lets assume A + B === C

Picture 5
Collision theory of A and B

It takes A and B to resect before C will be formed and only happens when particles of A and B interact i.e collide, and it is important to note that if they collide often then rate will increase.

Though it is important for particles to collide before products will be formed but it is also important to mention that not all collisions will form products in chemical reaction.

In fact, it is pertinent tom mention again that no reactions is said to have taken place until there is formation of products.

Reaction rate is not necessarily ascertained by how long the particles have been in the vessel colliding but on the amount of products gotten over time.

What factors affect collision theory and rates of reaction?

I have to say that any factor that affects collision theory will definitely affect rate of reaction.

I will only talk about 3 factors that can affect collision theory and thus rate of reaction.

3 factors that affect collision theory and rates of reaction

There are basically six factors that affect rates of reaction, but I will concentrate on three factors that do affect reaction rate.

3 factors that affect collision theory.
Temperature: When heat is supplied to reaction mixture, temperature increases and thus increasing the average kinetic energy of particles. This increase in kinetic energy increases the collision rate (frequency of collision) and thus increasing the rate of reaction.
Concentration: When more particles are added to reaction mixture or concentration of aqueous reactants increased, then we will have more particles crowded in a smaller space leading to more particles colliding and thus increasing the frequency of collisions.
Pressure: When pressure is increased the volume of space available for the gaseous mixtures decreases making particles to be closer to each other leading to more particles colliding with each other which in turn leads to a higher frequency of collisions and thus rate of reaction.

In conclusion, collision theory states reaction will not occur until there is collision between the reactant particles and only a fraction of these collisions which is otherwise called the effective collisions leads to the formation of products.

Collision theory and rates of reaction are directly proportional and thus anything that affects collision theory affects reaction rate, so altering factors like Temperature, Concentration and pressure will often affect rates of reaction.

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