The aim of this experiment was to use four different ways of measuring the rate of a chemical reaction by conducting a series of experiments finding out how quickly enzymes work. Method – {SEE SHEET} Results Summary Enzyme End Point Min (s) End Point Min Rate Of Reaction Amylase (Starch) 1:30 1. 5 0. 66 Trypsin (Marvel) 2:05 2:08 0. 48 Trypsin (Photo film) 9:48 9. 8 0. 15 Catalase Hydrogen Peroxide & Yeast 15 0. 25 4 Interpretation of results From my results I see that the fastest method was method 4 the floating disc method.
Using this method for a future experiment could turn out to be difficult because the reaction occurs quickly. But this method could be repeated. Using the disappearance of a substance method could be accurate way of measuring the rate of reaction but would be difficult one to do as the end point should be fully understood before the reaction. Class Results Summary Measure of Central Tendency 1 Amylase (with Starch) 2 Trypsin (with Marvel).
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3 Trypsin (with Photographic film) 4 Catalase (yeast with hydrogen peroxide) Mean 7 1 Amylase breaks down starch into maltose In this experiment starch is digested as soon as the I/KI stays the same colour (Orange). The I/KI would turn a blue-black colour first. 2 Trypsin is an enzyme that digests protein. Marvel has protein inside. When the Trypsin digests the protein the marvel solution becomes clear. The point at which the marvel solution and the Trypsin combine and the point at which the solution becomes clear is the end point. 3 The photographic film contains a protein.
The Trypsin mixes with the protein and breaks it down the photographic film becomes white/colourless – this is the end point. 4 The yeast contains the enzyme Catalase. This Catalase breaks down the Hydrogen Peroxide (2H2O2) and releases oxygen bubbles that move the filter paper (with yeast) upwards. The time is then recorded. Interpreting Class Results There are many differences in the results. The ranges on most (one exception maybe method 2) experiments are very high. Some of the reasons for this are discussed in the Sources of Error section.
Just from these values I cannot determine whether the larger range is correct or the lower range is correct. However, by looking at the mode, for example on experiment 2, 0. 25 comes up 3 times this could mean the real figure lies around at area. I can determine that experiment 4 was very quick in terms of rate of reaction for all class students. Evaluation In this experiment I successfully carried out 4 investigations into enzyme rate of reaction. All four tests were generally quite simple and could have taken less than the allocated time (Approx 1:30min).
Sources of Error The following points outline the typical sources of error in all 4 experiments. Contamination of solutions due to not thoroughly cleaning equipment with distilled water, or not emptying the water contaminated with a particular solution Inaccurate measurements e. g. not properly reading the meniscus or not properly removing all air bubbles trapped in the burette. The high concentration of yeast in the jar goes to the bottom so when the disc is soaked you really are picking up less concentration of yeast (Method 4).
Deciding the end point; it is difficult to know when the photographic film is clear (method 3), or the exact moment when the I/KI colour stays the same (method 1). In the case above I could have used a colorimeter for more accurate measurements or kept a reference colour to know when Marvel disappears (method 2). The benefits of this experiment are that it is quick and relatively simple to do. One deterrent from this experiment is its accuracy or finding the end point. This could be overcome by repeating measurements (knowing when the end point is), so the results are valid and consistent.
Conclusion The four methods I did are very simple ways of measuring the rate of reaction in terms of enzyme activity. To obtain accurate measurements the tests need to be repeated 3-4 times. And it is vitally important to know when the end point of the reaction is. 1 Show preview only The above preview is unformatted text This student written piece of work is one of many that can be found in our GCSE Patterns of Behaviour section.
