The input variable I am going to change is the concentration of the Amylase. The variables I must keep the same are: -
- The temperature that the experiment is done at.
- The different volumes of the Amylase and Starch.
The output variable I am going to measure is the time, which it takes for the reaction to occur to a certain point.
Diagram
Apparatus
2 test tubes, 2 peppiest, safety mat, test tube rack, testing tray, spotting tiles, stop clock, thermometer.
I am going to repeat the experiment 5 times each time changing the concentration of the amylase from 1-5.
Safety precautions that should be taken with this experiment are to wear goggles and to wash your hands afterwards.
Analysis
The greater the concentration the faster the rate of reaction. Each time the percentage increases by 1% the time increases by around 20-30 seconds.
My conclusion is that the rate of reaction is dependent on the concentration and as this increases the time taken for the reaction to take place will decrease. This can be explained by particle theory, which states that if you double the concentration you double the amount of successful collisions therefore doubling the rate of reaction.
Evaluation
When I look at my graph I can see that as the concentration of amylase goes up the time for the reaction to take place decreases.
I repeated my experiment two times to make sure it was accurate and then took an average from these results. To keep the experiment a fair test I kept the shade of blue I was using for the indicator to change to the same throughout the experiment. There were enough results as I was able to make a graph and plot a line of best fit on it. There were no anomalous results on my graph. If I was to do this experiment again to make the results more accurate I would place the test tubes with the starch in and the amylase in a water bath which I would keep at a constant temperature throughout the experiment. I would do this because when I did my experiment I did it at room temperature which meant as people were moving around in the classroom the temperature that I was doing my experiment at was increasing therefore making it a unfair experiment as the were other variables being changed. If I were to carry out my investigation even further to support my conclusion I would choose different enzymes such as protease instead of amylase. Also I would look at how much sugar was being formed in the reaction. I would do this by adding Benedict to the completed reaction and boiling it. If sugar has been produced the colour should go from blue (no sugar) to red (sugar). This would be measuring the production of sugar instead of the digestion of starch.