Reliability of evidence
I do not think that all of our results are accurate. I believe this because the range of results was quite high. For example, in the 10:40 ratio experiment some people recorded 190 seconds to collect 10cm3 of carbon dioxide and others recorded up to 532. Clearly this cannot be correct, as the figures are too far apart (the range is too great). If all of the results were accurate then the number of seconds recorded would have been similar or at least closer together. There were a number of similar differences recorded in other concentration results. I suspect that some of the results in these cases were also inaccurate.
Some of the results look wrong because they do not fit the pattern. For example somebody recorded a time of 4 seconds in the 40:10 experiment and the quickest time in the 50:0 experiment was 6 seconds. This cannot be correct as we know the higher acid concentration then the quicker the time should be to collect 10cm3 of carbon dioxide. This is and “outlier” and does not fit the pattern on the graph.
Not everybody collected results for each concentration and we also left out any outliers as they would affect the average and make analysing the data very difficult. I think that all of these experiments should have been redone.
Some of the results did not fit the overall pattern on the graph. This is because the results were not accurate. The results were not accurate because errors may have occurred where people did not measure correctly and also where there may have been water in the beaker and cylinder already as well as equipment not working properly.
We conducted several repeat measurements. I think the results are reliable enough to come to a valid conclusion. However because we did not make any changes or improvements to the way that we did the experiments, the repeated measurements were possibly as inaccurate as some of the initial results. I think that the conclusion that increased acid in the acid:...