The Manganese Oxide was then placed into the conical flask, which was then immediately sealed with the bung, and the stopwatch was started. The amount of air displaced was also measured when the bung was fastened to the conical flask in order to subtract from the final reading. After 10 seconds the volume of air produced by the reaction was measured and the conical flask was detached and cleaned. This process was repeated seven times, except with different concentrations, and 0. 4M. This was to obtain a good set of results by taking a range of different readings.
The concentration however was changed in all these experiments to observe the affect of it on the rate of the reaction. Experiments were done with Hydrogen Peroxide 50-0 Water, Hydrogen Peroxide (these are the ratios of Hydrogen Peroxide-water). In the molars this isThe whole set of experiments were then taken again twice in order to obtain a good average.
Results Having already obtained a good set of values from the trial experiment with the volume of liquid I had no problems as I started with 50ml and this turned out to be appropriate. My results were read by the amount of gas collected over 10 seconds. The reason I chose 10secs to be my reading is that it showed the initial rate of reaction, which was the part of the reaction that is mainly affected by concentration. As I was working by myself this method was not only more practical but easier as well as some experiments would accelerate very quickly so it was hard to read off the value in time.
By this method I had plenty of time to put the bung on and take the reading easily. Also I found that if I used 20secs as my reading the gas syringe would fill up too much and fall off on the higher concentrations. The results on the table below show. The higher concentrations Concentration of Hydrogen Peroxide Immediate Displacement of air Volume of Oxygen produced In 10secs (1) Displacement of air Volume of Oxygen produced In 1secs (2) 1 The higher concentrations have evolved more gas.
The reason for this is that there is more collisions due to the higher amount of particles that will react contained within the liquid. This can easily be shown on a diagram like below. As you can see if there are more collisions there is more gas evolved in a short amount of time, as the time in which it takes certain particles to collide is quicker. However this does not change the amount of gas evolved over a long time as no matter how concentrated the mixture is after a long period of time it will have all reacted and overall will have produced the same amount of gas due to similar volume of the two mixtures.
This is why we took the reading at ten seconds, as it would show the real difference between the concentrations. Errors: The first error in my experiment is that the measurement of my Manganese Oxide I found sometimes to be inaccurate as when it was emptied into the conical flask not all the contents of the paper fell off and thus the reading was affected. This was the same as the errors I found in the trial, so after the experiment I weighed the paper to make sure that all the Manganese Oxide was deposited. If it was not then I repeated the experiment again to get better results.
Also due to the fact that I was by myself I was often in a hurry and as a result of this I often spilt the apparatus as I was in such a rush to do everything in time. Due to this I had to start three experiments again. Modifications: One modifications I could possibly make is that I would do it in a pair As having done a trial experiment there was nothing really that I could obtain better by using a different method therefore the only modification would be to do it in a pair, as it would be easier to obtain the data and carry out the experiment.
Another is that I would measure the weight of the piece of paper after the experiment to make sure all the Manganese Oxide had been deposited. If it had not I would repeat the experiment. Conclusion: Having studied my results and reading over my recordings the experiment has led me to believe that my hypothesis was correct. As the higher the concentration of the Hydrogen Peroxide, the quicker the reaction rate was. For instance a concentration of 1M produced 51ml and 38ml of Oxygen in 10secs, whereas a concentration of 0.4M only produced 10ml and 14ml.
This clearly shows that the higher the concentration of the Hydrogen Peroxide the higher the reaction rate. Gcse Chemistry Coursework 2002-05-03 Leonard Percival Gcse Chemistry Coursework 2002-05-03 Leonard Percival 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.