he aim of this experiment is to find out how temperature effects the rate of a reaction between Hydrogen Peroxide and yeast. Prediction I predict that as temperature increases so will the rate of the reaction (up to a certain temperature, at which it will no longer ‘function’). Once the temperature gets to 50i?? C, the enzyme breaks down and stops working. However, rises in temperature of 10i?? C should be expected to double the rate of reaction. Background Information Yeast is an enzyme, an enzyme is a biological Catalyst made up of protein which speed up different chemical reactions without being used up themselves.

Enzymes have a very unique shape. This unique shape only reacts with one or two substances. When it does react with a substance molecules of that substance get trapped on the Active Site and either creates two molecules (Anabolism) or splits up a molecule into two (Catabolism). When the molecules are trapped they, therefore, collide more frequently and therefore increase the rate of reaction. Basically, enzymes speed up the rate of a reaction by lowering the activity energy. Below is a diagram of an enzyme, notice the unique shape which only certain molecules will react with.

The enzymes work at their best at 37i?? C (average human body temperature). If the temperature is above this then the substance fluctuates and is distorted so it is not trapped as easily in the active site. However, if the temperature is too low the enzyme will not function either. Lower temperatures immobilize the molecules by reducing the amount of kinetic energy while higher temperatures denature the substance. From my preliminary work I found yeast reacts reasonably well with Hydrogen Peroxide at around roughly 17i?? C so we will be taking readings around this number.

We also found that after 200 seconds there was little to no reaction taking place, we will therefore only record results from 0 seconds up to and including 200 seconds. Key Factors There are several factors that can greatly effect the experiment. The main factor is of course the temperature of the water which we will control (as mentioned above temperature can change the reaction rates severely). If we decide to shake the test tube, then we must do so for every reaction, shaking the test tube will increase the rate of reaction and therefore must be kept constant.

The amount of the solution is also a factor which we must control, but using pipettes this will not be very hard. Diagram Apparatus Here is the apparatus we will use:  Burette  Boiling tube Delivery tube Water bath  Pipette  Measuring cylinder  Clamp & stand Method Temperature will be pre-set by a water bath, the starting temperature will be 13i?? C (roughly room temperature). We will take readings from 0-200seconds and repeat one experiment to see if our results are accurate. Here is what we will do:

We will set up the equipment as shown above.  We will fill the burette with water and place it upside down in the water bath.  A boiling tube will be set up and a delivery tube will connect it with the burette in the water bath.  We will then measure out 12cmi?? of water and place it into the boiling tube. Using a pipette for greater accuracy, we will measure out 1cmi?? of yeast and 2cmi?? of Hydrogen Peroxide. The yeast and water will be placed in the boiling tube and then once we are ready we will add the Hydrogen peroxide.