The effect of changing the concentration of the Enzyme catalyst on the Rate of Reaction on Hydrogen Peroxide

GCSE Science

Jennifer Hooper

Planning

Hydrogen Peroxide Water + Oxygen

2H2O2 2H2O + O2

Introduction – Background Information

To help me understand what a chemical reaction is or involves I did some research.

A chemical reaction is a process by which atoms or groups of atoms are redistributed, resulting in a change in the molecular composition of substances.

Enzymes are a biological catalyst, which controls a cellular reaction, they are proteins that act as a catalyst. A catalyst is a substance that speeds up a reaction but does not get used up. It works by reducing the Activation Energy, which is the minimum energy needed for a reaction to happen. A catalyst can make a reaction occur even if it would not happen other wise. Enzymes only affect the speed at which a product is formed, not how much is produced. Enzymes are specific, this means that once an enzyme has acted on one substance it will not act on a different one.

There are two reactions which involve enzymes they are anabolic and catabolic. An anabolic reaction is a build up of smaller molecules into larger molecules. A catabolic reaction is the speeding up of the reaction time but is the breaking down of a substance. I will be focusing on the catabolic reaction. To explain the reaction there is a method called the lock and key theory:

The Collision Theory – this is when reacting molecules collide with each other with enough energy to react. Surface area, temperature, concentration and the use of an enzyme affect the collision theory.

All of these factors increase the rate of reaction if you increase them. If there is a larger surface area then the molecules are exposed and are more available to react as there are more of them. This means there will be more collisions so a faster reaction.

If you increase the temperature this will make the molecules move more quickly, so they will collide more often with greater energy, so there will be more successful collisions, therefore increasing the rate of reaction.

If you increase the concentration the molecules will be closer together therefore colliding with each other more often. This will mean an increase in the rate of reaction.

A catalyst speeds up the rate of reaction, but does not get used up.

Factors that affect how well an enzyme works

The temperature.

The pH of an enzyme.

The concentration/amount/volume of the enzyme.

The concentration/amount/volume of the substrate.

The pH and temperature of which an enzyme works is called its optimum.

If the temperature increases it will increase the rate of which the enzyme works therefore increasing the rate of reaction. If the temperature decreases it will slow down the rate of which the enzyme works therefore decreasing the rate of reaction. This is because if you increase the temperature the molecules will move quickly with greater energy causing more collisions and therefore increasing the rate of reaction.

Most changes in the pH of an enzyme are reversible. An enzyme that was working at ...