# What is collision theory? How does it relate to surface area and temperature?

May 5, 2018

Refer to Explanation.

#### Explanation:

Collision Theory

• From the kinetic theory of matter, particles are in constant random motion. As a result, many collisions occur.

• For a chemical reaction to occur, the reactant particles must collide.

• Although particles must collide to react, not all collisions are successful in producing a reaction.
• Only a small fraction of collision will result in a reaction. Such collisions are called effective collision.
$\textcolor{w h i t e}{\ldots} \to$Reason: All colliding particles need a minimum amount of energy before a reaction will occur.
$\textcolor{w h i t e}{\ldots} \to$This energy is called activation energy, ${E}_{a}$. Below ${E}_{a}$, a collision that occurs cannot lead to a reaction.

How does it relate to surface area?
As the surface area of the reactant particles increases, the frequency of collisions between the reactant particles increases and this results in increase of chances of effective collision thus leading to a faster reaction.

How does it relate to temperature?
When the temperature is increased, the particles absorb more energy. They move faster and thus collide more frequently. More importantly, there is also an increase in the number of reactant particles having activation energy. Hence the chances of effective collision increases and the rate of reaction increases.