No one fully understands how catalysts work. Sometimes they seem to bring the reacting particles close together, making it more likely that they will collide. Often they lower the activation energy for a reaction, so the particles do not need to collide with so much energy to react.
Using a catalyst often means that a reaction will take place at a much lower temperature. This is why catalysts are very widely used in industry, because lower temperatures mean the process is cheaper to run - and that can make all the difference to the economic success if a company.
Enzymes allow chemical reactions to take place quite quickly at the temperatures and pressures normally found in living things. Just like inorganic catalysts they lower the activation energy of reactions and bring reacting particles close together.
Enzymes are biological catalysts that speed up the rate of chemical reactions. Starch is a large molecule made up of glucose molecules joined together. Amylase is an enzyme (biological catalyst) that breaks up starch into single sugar units. The particular amylase enzyme I shall use is a fungal enzyme that only gets damaged or destroyed by temperatures of 80C and up.
The variables I shall be dealing with are:
- Temperature
- Amount of starch
- Amount of enzyme
- Concentration of starch
- Concentration of enzyme
The variable that I am going to change is the temperature that the reaction will take place at. Because I do not want to damage or destroy the enzymes I shall start my experiment using a minimum temperature of 40C. From this temperature I shall do 5 more experiments at temperatures up to a maximum of 70 C to give me a set of 6 readings. I will then repeat each experiment to confirm my readings, and so that I can work out an average time for the reactions to take place at certain temperatures.
Here is a diagram of the apparatus I shall use:
I predict that as the temperature is raised the reaction time will decrease.
I think this because according to the background information the enzymes make the reaction possible at lower temperatures so in theory if the temperature is raised the reaction should speed up as long as the enzymes are not destroyed or damaged by too much heat.
To keep the tests fair I am going to use the same amount of amylase, iodine, and starch in the solution in each experiment.
I carried out this test by getting boiling tubes and washed them out to rid them of impurities from past experiments they may have been used in. I decided which one was going to be the control and which one was going to hold the test tube containing the amylase enzyme, poured 5mls of 0.5% starch solution into each and placed them in a beaker containing hot water. I then added three drops of iodine to each boiling tube to make the 0.5% starch solution turn a dark purple colour. I then poured 5mls of water (H2O) and 5mls of 1% amylase solution into the boiling tubes instantaneously while my partner operated the stop clock as soon as the solutions mixed. I then watched the solution until the contents of either one of the boiling tubes became transparent (clear). When this happened I stopped the stop clock and noted down the time.
The safety rules I had to follow to protect myself and other people from harm while doing the experiment were;
Do not be silly at all especially while using iodine.
Always wear safety goggles to protect eyes.
Wash iodine of skin immediately.
Do not contaminate either of the solutions.
To check the accuracy of my results I repeated the experiments twice so that I can work out an average time for the enzyme to turn the starch into sugar at certain temperatures. By doing this I have greater confidence in my results. I have put my first set of results into a graph.
I am also going to put my results into some graphs.
From this table and graph one I can see that my prediction was right, and by looking at my results I can clearly see that the higher the temperature is the quicker the reaction happens. This does not surprise me for the hotter something is the quicker the molecules move causing them to bump into other molecules more often and in this case breaking them up quicker. I shall now do the same experiment again so that I know my results were correct or to show if I did some thing wrong in my first experiment.
I shall now put my second set of results into another table and a second graph.
From my results I can see that the higher the temperature the quicker the starch gets turned into sugar by the amylase enzyme.
This has proven to me that temperature does have an effect on the reaction between starch and amylase. The reason why the iodine fades out is because a reaction takes place between the starch and amylase, which changes starch to sugar, has successfully taken place. As the temperature went up the reaction happened at a faster rate. This is because as the molecules heat up they gain more kinetic energy and move faster causing the amylase molecules and the starch molecules to bump into each other which means that the experiment will happen faster.
By doing this experiment I found out that amylase reacts with starch to make sugar. I also found out that temperature also effects the rate of reaction. I could also have tested the solution after the experiment with blue benedicts to make sure that the product from the reaction was sugar as well.
If I was to do the experiment again I would improve the experiment by making sure the water temperature doesn’t drop. I could possible do this by some form of insulation. I would also like to be able to use a different method of timing the reaction rather than having to do it myself, and last of all I would like to be able to measure the solutions with more accuracy. I might also do a different experiment where I change the concentrations of the liquid used.
Here is a diagram of what happens:
