An enzyme is a biological catalyst. A catalyst enables substances to react more quickly. Atoms break and form easily which are between bonds which are helped by catalysts. The particles need less energy, so the proceeds more quickly. For example, catalysts are now used in car exhaust systems. Car fumes contain poisonous carbon monoxide and nitrogen oxide. These pollutants react together very slowly to form, carbon dioxide and nitrogen which are not poisonous. Carbon monoxide + nitrogen oxide –> Carbon dioxide + Nitrogen 2Co + 2No –> 2Co2 + N2.

When the exhaust’s fumes pass over the platinum, the carbon monoxide and nitrogen oxide react together very rapidly. However, none of the platinum is used up during the reaction. The mass of platinum is the same after the reaction as before. The platinum has acted as catalyst. Therefore we state a catalyst as a substance which alters the rate of a reaction without being used up.

(Reference: revise GCSE Single and Double award) There are different factors that affect the reaction rates. They are the following:  Surface area  Temperatures  Concentration Ph Heat.

The surface area of a solid is the area of it which is exposed. If a solid is cut smaller pieces, the more surface area is exposed, hence it will react faster. The reaction occurs when particles collide. Concentrations in general react more quickly than dilute ones. For examples, a concentrated detergent removes grease more quickly than dilute detergent. In a concentrated solution there are more collisions per second between the reacting particles, so the reaction proceeds more quickly. Enzymes only work on one reaction due to their shape. The temperature differs how quick the particles move.

The higher the temperature, the faster the particle moves. They therefore collide more frequently and with more frequently and with more energy. This then makes it easier for them to react together. Usually, rises of 10? c will double the rate of a chemical reaction. Graph A The rate of reaction doubles with every 10? C rise in temperature. This is because the molecules which are reaction move faster and have energy at higher temperatures. Graph B Between 0-40? C, the rate, the rate of reaction rises in just the same way as in graph A for just the same reason.

At 40?c, the enzyme begins to be damaged, so the reaction slows down. By 60? C, the enzyme is completely destroyed. 40? C is the optimum temperature; the temperature at which the rate of reaction is greatest. Most of the chemical reactions are happening inside a living organism controlled by an enzyme. Enzymes are very sensitive to high temperatures to high temperatures. On the temperature gets about 40? C they begin to be damaged. When this happens to an enzyme, it cannot catalyze its reactions as well, hence the reaction slows down. At higher temperatures, the reaction will stop completely because the enzymes.

Prediction I predict that the higher the concentration of the enzyme the faster the reaction. In general, concentrated solutions react more quickly than dilute ones. In a concentrated solution react more quickly than dilute concentration. In a concentrated solution there are more collisions per second between the reacting particles, so the reaction proceeds more quickly. As you increase the concentration, it will rise until a point where it stays constant because the enzymes have run out of active sites which slows down the rate of reaction. To keep in the reaction rates increasing, it can have more enzymes.

This then suggests that f you double the concentration, you will double the enzymes therefore you will double the reaction rate. The lock and key theory applies to the process of how starch is broken down in to maltose. Only one enzyme is designed for one particular substance, therefore it cannot react to another substance. The reason it cannot do this is, because the shape of it is different to the substance. The downside of this process is that only a limited amount can fit at the active sites which can makes the process itself slow. Apparatus Spotting palette 1% starch Concentrated solution 0.25%-1. 25% Pipettes Iodine Test tube Test tube rack Timer Method 1. Put 2 drops of iodine in to each dimple on the spotting tray.