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Method I generally followed most of my plan for the experiments, but to improve accuracy and reliability, I made one change. In my plan, I said that I was going to use 20cm? of starch for each experiment. However, in my actual experiment I used 40cm? of starch. This is because I thought I might not have had enough solution if I only used 20cm? of starch. If this was the case, then I would have to stop the experiment half way through, which would have prevented me from obtaining accurate results. So for this reason, my results would be more accurate and reliable. For everything else, I followed my original plan.
To ensure the results were accurate, I made sure I accurately measured out the amylase and starch solutions for each experiment. This is because, if I had the wrong amounts, I would not get a valid conclusion, as I will not know whether my results are affected by the concentration of starch, or whether the results I got were due to the amounts of solution used. This would make both my results and conclusion invalid and unreliable. I also made sure that the temperature of the water bath was at the correct temperature and I kept on checking the temperature of both my amylase, and starch using a thermometer.
I made sure both solutions were at the same temperature at all times throughout my experiments, so that temperature would not have an effect on my results. This would help me obtain more reliable and accurate results. Also, I made sure that I was drawing the solution up in the pipette beforehand, so that I could put it into the cuvette at exactly 30 seconds. This would make my results more accurate, as the solution would be put into the cuvette at precisely 30 seconds and so time would not have an effect on my results.
I also used separate pipettes to measure out the starch, amylase and distilled water so that the solutions don’t mix together before the reaction should start. Also, I repeated each of my experiments two times to make sure I get accurate results. Finally, when I was making up the different concentrations of starch, I made sure that I accurately measured out the distilled water and starch, so that I get the correct concentration of starch. Results Below are my results for each concentration of starch, for both the original experiments and the repeats.
I obtained my results by putting the cuvettes into a colourimeter and taking a reading for the percentage transmission after every 30 seconds. I used a colourimeter as this would give me numerical values and so my results would be more accurate, because I could not measure the colour intensity accurately by myself, as I can’t put a scale on that. For this reason, the likelihood of human error is minimised. I used a reference point of just iodine solution and distilled water, which was a reading of 100% on the colourimeter. 0. 2% starch Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 0302931 120454446 150585759 180706971 210767577 240848385 270908991 3009998100 0. 4% starch Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 90111 120111 150182018 180313030 210504951 240565456 270575957 300646563 0. 5% starch Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 90444442 120585657 150727171 180787778 210848284 240868787 270898989 300908990 0. 6% starch Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 90131513 120434141 150575756 180626563 210716971 240747475 270767778 300787979 0. 8% starch
Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 90161617 120555454 150707371 180777678 210939293 240949495 270969896 300999999 1% starch Time (secs)% Transmission% Transmission (Repeat 1)% Transmission (Repeat 2) 30111 60111 90171718 120555655 150696870 180767576 210929393 240949595 270979897 300999999 I will now take an average of the results for each concentration and plot them on a graph – % transmission against time. 0. 2% starch Time (secs)% Transmission 301 601 9030 12045 15058 18070 21076 24084 27090 30099 0. 4% starch Time (secs)% Transmission 301 601 901 1201 15019 18030 21050 4055 27058 30064 0. 5% starch Time (secs)% Transmission 301 601 9043 12057 15071 18078 21083 24087 27089 30090 0. 6% starch Time (secs)% Transmission 301 601 9014 12042 15057 18063 21070 24075 27077 30079 0. 8% starch Time (secs)% Transmission 301 601 9016 12054 15071 18077 21093 24094 27097 30099 1% starch Time (secs)% Transmission 301 601 9017 12055 15069 18076 21093 24095 27097 30099 I will now plot these results on separate graphs. I have plotted the graphs for the average % transmission against time. I did a separate graph for each concentration of starch. I then worked out the gradient of each curve by drawing a tangent.
I worked out the gradient by doing the difference in y divided by the difference in x. The gradient represents the rate of reaction. I will now need to draw a final graph to show concentration of starch against rate of reaction. Below is a table to show the rate of reaction for each concentration. Concentration of starchRate of reaction 0. 2%0. 4 0. 4%0. 5 0. 5%0. 7 0. 6%0. 7 0. 8%0. 9 1%0. 9 I rounded the rate of reaction up to 1 decimal place so that it would be easier for me to plot these values onto the graph accurately. I will now plot a graph for concentration of starch against rate of reaction.