Results
Results of Unknowns
Conclusion
Once the potassium permanganate was added to the acidified solution the solution became purple in colour. The solution then gradually changes colour from a strong purple, then through lighter shades of purple onto what at first appears clear but once compared against a white tile it was possible to detect a yellow tinge to it. The timer was then stopped only when the solution became completely clear.
From completing the experiment and producing the graph it is possible to deduce that the lower the strength of the solution the more time it takes for complete decolourisation of potassium permanganate. This means that the time of the reaction is dependent on the concentration.
Evaluation
Problems first occurred in making the glucose solutions. The problem was that an extra 1cm of 10% glucose was added due to confusion with the pipette. This may have been prevented if a syringe had been used. However the pipette gives greater accuracy.
The next problem occurred when the potassium permanganate did not completely mix with the acidified solution, due to the potassium permanganate being added too quickly in an attempt to make sure that it was added all at once and fairly. This meant that there was some potassium permanganate that was not being decolourised. This led to some of the results being marginally slower than they should have been.
The main difficulty in this experiment is that is hard to determine the end point when the solution complete decolourises. This is because it is possible to believe that the solution is completely clear when the truth is that the solution has not decolourised completely. Due to the difficulty to determine the end point there is also the possibility that you may go past the end point therefore recording the incorrect results. The difficultly results in it being impossible to correctly identify the end point in this experiment, this means that no possible results that you may obtain can be completely correct, there will always be a slight margin of error. Although it is impossible to be completely correct on the end point of the experiment. One possible improvement would be to draw a black cross on a piece of white paper which would be placed below the test tube. This would help distinguish the decolourisation of potassium permanganate. Another option to distinguish the colour change would be the use of a colorimeter to determine residual colour after a given time.
There are slightly anomalous results at 4 and 6 % glucose solution. Possible reasons for the errors causing these anomalous are that not all of the potassium permanganate fully mixed causing only partial complete decolourisation while there is still a layer of deep purple coloured potassium permanganate above it. An additional problem occurs in that the end point may not have been completely reached or may have passed; in either case the time recorded will have been incorrect.
There are limitations to this procedure, e.g. the timer is not precise enough therefore leading to results that are not sufficiently accurate to get perfect results. This could be improved by using a more accurate timer, or maybe timers, then find the average time elapsed. A separate limitation would occur if there were not enough results to procure a correct conclusion. One improvement would be to collect a large varied selection of results; this would mean that there would be more evidence to corroborate the conclusion. These limitations, if not resolved, may result in error.
The experiment could improve by using a less subjective method; this could be done by reducing the intricacy of the method. This would lead to the method being easier to follow therefore increasing the ability of obtaining improved results
