Therefore, I predict that as the temperature increases, the speed of the reaction will increase. I believe this because most chemical reaction happens faster when the temperature is higher. However, when a particular temperature is reached I believe the rate of reaction will dramatically decrease.
I will need the following equipment for this experiment:
- Test Tubes
- Test Tube Rack
- A Thermometer
- A Measuring Cylinder
- A Electronic Water Bath
- Starch
- Amylase
- Iodine
- A Syringe
- A Stop-Watch
To be sure the experiment will work; I will first carry out a pilot experiment. For this I will:
- Measure and pour 2cm³ of Amylase into a test tube. Measuring will be done using a syringe.
- Measure and pour 3cm³ of Starch into another test tube, and add 3 drops of iodine. A blue/black colour should develop.
- Heat-treat the Amylase first for 1 minute in a warm water bath.
- Add the contents of both test tubes together, and place in a water bath. Begin timing. Record the temperature of the water bath at that moment.
- The blue/black colour should begin to disappear and leave a clear solution in the test tube. This will be the control of the experiment. When this has happened, stop timing immediately and record results.
For my experiment, I will have to modify the pilot experiment in a number of ways. Since I have decided to invest how different temperatures affect the rate of reaction, I will have to modify the temperatures of the water baths to get a broad range of results.
To ensure that this is a fair test, everything else will be kept the same. I will repeat the experiment 3 times at each temperature. This will allow me to calculate an average time, and to make sure I get accurate results, and no anomalies. I plan to make accurate measurements; any anomalous results will be repeated.
To make the experiment safe, I should wear goggles to keep my eyes safe from harmful things like hot water. I will also use a test tube rack to keep my test tubes in order and stable.
The results in the above table prove that my hypothesis was correct and that the above results support this. We can see that between 17-59˚c the speed of the reaction increases as the heat increases. However, we see that in the 80˚c and above test that the enzyme has denatured, and the hotter the enzyme gets then, the slower the reaction becomes.
From plotting the results onto my graph and adding a line of best fit, we can pick out a trend. Between 0-59˚c, the rate of reaction dramatically increases as the temperature increases. Between 59˚c and 80˚c, the reaction slows down dramatically. From 80˚c and above however the reaction only slows down by around 2-3 seconds every 10˚c more. This suggests that almost all the enzyme has denatured at around 80˚c.
I do think the experiment worked well, however I think that because I only did 5 temperatures my results may not be as accurate as they could be. When drawing my line of best fit, there were only five spaced out points to go through. I decided to conduct the experiment at 10˚c intervals instead of 5˚c intervals because there was not enough time. I also only conducted the experiment 3 times for each temperature to save time. I feel that with a broader range of results, my conclusion would have been much more accurate, and perhaps in future experiments I could take this on board.
Additional work, which could be carried out, is to repeat the experiment using different pH levels, and a range of different starch solution concentrations.
