# How can the rate of reaction be changed?

Aug 26, 2014

There are several ways to change the rate of a reaction.

Anything that increases the number of collisions between particles will increase the reaction rate. Anything that decreases the number of collisions between particles will decrease the reaction rate.

• CHANGE THE CONCENTRATION OF A REACTANT

A higher concentration of reactants leads to more effective collisions per unit time and leads to an increasing reaction rate.

• CHANGE THE PRESSURE OF A GASEOUS REACTANT

Changing the pressure of gaseous reactants is, in effect, changing their concentration. The increased number of collisions caused by a higher pressure increases the reaction rate.

• CHANGE THE PARTICLE SIZE OF A SOLID REACTANT

Reaction rate depends on collisions. If a reactant is a solid, grinding it into smaller particles will increase the surface area. The more surface area on which collisions can occur, the faster the reaction.

• CHANGE THE TEMPERATURE

Ann increase in temperature causes an increase in the reaction rate. A higher temperature means that the molecules have a higher average kinetic energy. This produces more collisions per unit time. It also increases the number of collisions that have enough energy to cause a reaction.

The rate of a chemical reaction depends on the solvent in which the reaction occurs. It may make a difference whether a medium is aqueous or organic (polar or nonpolar).

Catalysts increase the rate of a chemical reaction without being consumed in the process. They do this by an alternative mechanism that has a lower activation energy.