# rates of reaction

Rates of reaction coursework

Introduction

The rate of reaction may be measured by following the loss of a reactant, or the formation of a product. The rate of reaction is just how fast it goes. We measure the rate of reaction by measuring the time taken for the reactants to be used up or products to be formed.

A chemical reaction can only occur between particles when they collide. There is a minimum amount of energy which colliding particles need in order to react with each other. The faster the particles are going, the more energy they have and they are more likely to react

Temperature

One of the things that affect rate of reaction is increasing the temperature of a reaction. At higher temperatures reactant particles move faster and collide more often and more violently and more successfully. This means they are more likely to combine this therefore increase rate of reaction.

Concentration

Increasing the concentration of reactants also increases the rate of a reaction. This is because there are more particles in the same volume so more collisions are possible every second. If a solution is more concentrated it means there are more particles of the reactant knocking about between the water. The more collisions happen and the greater the rate of reaction.

Surface area

Breaking up solids into smaller pieces increases reaction rate because this increases the total surface area. Increasing the surface area must increase the number of particles of the solid in contact with the other reactant in solution. An increase in surface are must increase the number of particles of the solid in contact with the other reactant in solution so therefore the larger the surface are, the more collisions and the greater the reaction rate.

Catalyst

Using a catalyst increases the rate of a reaction. Catalysts are not used up in a reaction. A catalyst is a substance that changes the rate of a chemical reaction without undergoing any permanent chemical change. A catalyst lowers the amount of energy needed so more particles will have the required energy for successful collisions. It is called a positive catalyst if it speeds up the reaction. A negative catalyst slows down the rate of reaction.

Pressure

If the pressure is increased the particles in the gas are pushed closer. This increases the concentration and thus the rate of reaction.

Collision theory

When the solutions are reacting the collisions have sufficient activation energy. This is the minimum amount of energy that is required to activate atoms/molecules to undergo a chemical transformation. Increasing the temperature brings more collisions and an increase in rate of reaction.

Preliminary work

I carried out a preliminary test to practice so learnt how to improve on the real test we realized that we needed to do the test 3 times.

In a previous experiment we also carryout an experiment to show how concentration affects rates of reaction this is what my results ...