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This will be repeated until the weight of the test tube with its contents is identical. E. g. 1st reading= 17. 24g, 2nd reading= 17. 18g, 3rd reading=17. 15g, 4th reading=17. 15g The underlined readings are identical; consequently I would stop and record these readings. I would do it like this because when the readings are the same it means that the reaction has stopped and there is no need to go any further. This is done for every amount. Fair Test There are many things that can be done to keep this experiment a fair one.
Firstly the same test tube must be used as all of them have different weights.
The amount of time you leave the test tube on the Bunsen burner is also crucial, as it would not be a fair test if you left one test tube in the heat longer than the others. You must measure the amount of mineral wool you put in the test tube so that you can deduct that and the weight of the test tube to get your result.
Errors will be kept to a minimum with the use of digital weighing equipment. Preliminary work My preliminary work consists of an experiment titled ‘Obtaining Copper Oxide from Malachite’. Malachite is a mineral that contains copper. In the experiment we heated the Malachite in an attempt to obtain Copper Oxide.
From the experiment I acknowledged that as the mass of Malachite increased so did the mass of Copper Oxide. The experiment was extremely similar to this experiment, thus I would expect the same to happen in this case.
Therefore, in this experiment, the more Calamine that is used the more Zinc Oxide that will be produced. It doesn’t take a genius to work that out though. -7- Jack Mariner Chemistry Coursework Results: Chart 1 Reading Amount of Calamine (g) Amount of Zinc Oxide produced (g).
Shown above are the results from the experiment and below is a graph plotted from these results. -8- Jack Mariner Chemistry Coursework Graph 1 is a bar chart showing the amount of Calamine used, plotted against the amount of Zinc Oxide produced. Although this graph may look pretty, it is not very useful. From just using these results, it is difficult to explain and understand the graph, so something else is needed: The theoretical amounts. Chart 2. No. of readings Amount of Calamine (g) Theoretical amount of ZnO Predicted (g) Actual amount of ZnO Produced (g).
These theoretical amounts have already been calculated. To add these to the graph like on the next page will help us to analyse the results in more detail. -9- Jack Mariner Chemistry Coursework Now this graph is worth looking at. It shows the theoretical amounts of Zinc Oxide produced, plotted against the actual amount of Zinc Oxide produced. So theoretically, in perfect conditions, with a perfectly fair test in practise, the theoretical results would be achieved. My experiment however wasn’t done in these conditions, which is why the results do not resemble each other perfectly.
-10- Jack Mariner Chemistry Coursework Graph 3 is a line graph, which I feel shows the information more clearly. From it you can see that the theoretical amounts are similar to the actual amounts of Zinc Oxide produced, however there is room for a lot of improvement. For instance, reading 2. This was done using 1. 5g of Calamine. Something definitely went wrong here because it is so out of proportion to the other results. Due to the obvious mistake I took the liberty of requesting a glimpse of another group’s results, to compare with mine and to see their result for 1. 5g of Calamine. Chart 3 Reading Amount of Calamine (g).
Actual amount of ZnO Produced (g) Other Group Comparison of ZnO Produced (g) From Chart 3, you can see that my results are in fact relatively similar to the other group’s results that I have compared with. The reasons for the differences are probably due to spillages or how concentrated the substances were, etc. Analysing the Results To analyse my results I shall look back at them individually. ‘Chart 1’ shows only my results. These were very pleasing because they were nearly as I predicted.
At this stage I wasn’t aware of any anomalous results as the relationship between them looked good. I am still satisfied with my results but would like to redo the test for 1. 5g of Zinc Carbonate. This would give better results to analyse and to draw a conclusion from. The second chart, ‘Chart 2’, showed the theoretical amounts. I included these into my experiment so that I could see how accurate my results were. Comparing with another group is good, but their results could also be wrong. Comparing with these theoretical results would show me immediately the accuracy of my results.
I have drawn the graph on the next page to demonstrate this. -11- Jack Mariner Chemistry Coursework So the graph is really a way of measuring your accuracy. To do this I worked out the percentage (%) yield. This was done by using the equation; % yield = actual amount theoretical amount From the graph you can see that the majority of my results were very accurate. I have done readings 2 and 4 in a different colour because they are obviously wrong. They both have a percentage yield of over 100%, which is impossible. The reason for this is probably due to contamination and impure Calamine. These two readings are therefore anomalous results.
‘Chart 3’ shows that my results are actually fairly similar to those from the other group. Apart from the obvious experiment error in reading 2, the thing that catches my attention most is the fact that my results are all higher than those from the other group. This could be resulted from a number of things, for example the use of different pieces of equipment, or the stopwatch counted seconds at slightly different rates, consequently that group leaving the test tube under the heat for a longer period of time. Or on the other hand these results maybe higher then the compared groups results as a complete coincidence.
-12- Jack Mariner Chemistry Coursework Conclusion From ‘graph 3’, you can see that my hypothesis is of high quality stating that I predicted a graph with strong positive correlation. This was almost a perfect prediction. My conclusion really for this experiment is that as the amount of Calamine increases so does the amount of Zinc Oxide produced from this. Theoretically this is done proportionately, but actually anomalous results interfere, leaving the results strongly related with strong correlation as apposed to a theoretical graph with perfect correlation.
Evaluation I consider this experiment to be a success. The plan was followed very well and the results were of good quality. The measurements were done accurately, and a fair test was achieved. The procedure used was also a very fair and efficient one. Although the experiment was a success, I am still bothered by the fact that anomalous results occured in my experiment. I think that the reasons for these results were because of time limitations. We had very little time to accomplish this task successfully, so mistakes were inevitable.
The improvements, which could be made in doing this experiment, are to have a longer time to do the experiment so that isn’t done making careless mistake and if mistakes were made, there would be enough time to redo what was needed. Secondly more high tech equipment could be used to get more reliable and accurate results. Also, an essential thing is for the Calamine used to be pure. This is important because impure calamine could react at a different rate to more pure Calamine. This would have a huge bearing on the final result. Lastly, more readings could have been taken. This would lead to averages being taken giving better results.
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