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Advantages and disadvantages of experimental design
Essays on experimental designs
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By analysing the results it could be seen that there was a relationship between the concentration of sodium thiosulfate and the time take for the cross to be no longer visible on the white tile through the solution. From graph 1 it could be seen that the concentration of sodium thiosulfate and the time taken for the reaction to be completed are inversely proportional, as when the concentration of sodium thiosulfate increases, the time taken decreases and the graph levels out as it approached the x-axis. Graph 2 supports this by showing that the concentration of sodium thiosulfate and the rate of the reaction share a linear relationship, meaning that the concentration is directly proportional to the inverse of the time taken.
From the graphs, it could be determined that the results are fairly precise due to the data points being fairly close rather than scattered. This can be seen as all the points are relatively close to the average value on graphs 1 and 2, not causing the trend line to be skewed.
Both graphs and data tables show that no anomalous results were present. This is evident within the data as no one point cause a major shift in the trend of the results.
A possible random error within the experiment may have caused scatter within the results is parallax error. This error may have occurred every time a measurement was taken from a measuring cylinder. This could have caused the time for the cross to disappear to be higher or lower than anticipated. If more thiosulfate were added, the reaction would have a lower average time and therefore a higher reaction time. The results showed that some data points had a higher reaction time than anticipated, meaning that this is a possible source of error within the experiment. ...
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...ld also do this. Both of these suggestions would give a better average and reduce scatter. Most of these changes are not necessary as the procedure is quite reasonable. However a change in the apparatus could improve the experiment. For example more equipment.
Conclusion
From the results gathered and the graphs drawn it is evident that the concentration of sodium thiosulfate is inversely proportional to the time take for the cross to disappear. Despite random and systematic errors being present, a trend can still be seen within the data. The experiment could be improved with changes to the procedure and apparatus.
The initial hypothesis held true when compared to the results acquired within the experiment. By completing the experiment it was found that the concentration of sodium thiosulfate was inversely proportional to the time take for the cross to disappear.
Record the volume of the sodium thiosulfate solution used in the titration, and repeat the procedure in a duplicate titration.
the replicate shows the same trend as the first experiment. I used a measuring cylinder and a beaker to measure out the amounts of water; however these did not seem to affect the quality of my results. To increase the accuracy of my results I could have perhaps used a burette. Even though I did the best I could to keep the experiment accurate, I did. some places there were mistakes that unintentionally occurred.
The results of this experiment are shown in the compiled student data in Table 1 below.
2. We get these irregular results because of the fact this program doesn’t take into account all factors which give us selection strength. Giving us irregular activity at C160.
to be done. This was to find out what amount of each liquid would be
Objective: The objective of the experiment is to determine what factors cause a change in speed of a reaction. It is also to decide if the change is correlated with the balanced equation of the reaction and, therefore, predictable. To obtain a reaction, permanganate, MnO_4^(1-), must be reduced by oxalic acid, C_2 O_4 H_2. The balanced equation for the reaction is:
...eadings. The absorbance readings for test tube 5, were always further away from the expected values than test tube 1. This is because the NaOH was not added to each tube at a time, but in sequential order with the test tube numbers. This allowed the reaction in test tube 5 to proceed longer than in test tube 1, allowing more product to be produced, giving a higher absorbance reading than expected. In fact, this trend was shown in all the test tubes. In increasing order of test tube numbers, every absorbance was more off than expected.
Above is my original data. In the graph, it can be seen that there are
Input variables In this experiment there are two main factors that can affect the rate of the reaction. These key factors can change the rate of the reaction by either increasing it or decreasing it. These were considered and controlled so that they did not disrupt the success of the experiment. Temperature-
.... The tests were all similar to one another and the results were moving as predicted. After repeating it with three different people per age group, most of the results had no big differences. The range bars were not very far apart and were closer together because of how similar the results were even before calculating the averages. This shows me my results are quite reliable because most of the data collected was alike, so they were not misinterpreted or mistakes.
The Arrhenius equation ln k = ln A – (Ea / RT) can be shown
There is also the potential of human error within this experiment for example finding the meniscus is important to get an accurate amount using the graduated pipettes and burettes. There is a possibility that at one point in the experiment a chemical was measured inaccurately affecting the results. To resolve this, the experiment should have been repeated three times.
Possible sources of error in this experiment include the inaccuracy of measurements, as correct measurements are vital for the experiment.
My aim in this piece of work is to see the effect of temperature on the rate of a reaction in a solution of hydrochloric acid containing sodium thiosulphate.
We must also make sure that we add both the water and the sodium thiosulphate at exactly the same time (into the beaker with the hydrochloric acid in it), or it could affect the results of the experiment. We must start the stopwatch at the exact time as we put the water and the sodium thiosulphate into the beaker. To do this, it is a lot easier if there are two people doing the experiment, so one person can put the two substances in the HCL, and one person can start the stopwatch. Also, the person timing the experiment will look for the disappearance of the cross, otherwise there would be a time lapse between seeing the cross disappear and telling the other person to stop the clock and then eventually stopping the clock. It is also important to keep the temperature the same to obtain fair results, however we do not have to worry about this as the temperature will be kept at room temperature throughout the experiment.