Aim: To find out how much the concentration affects the reaction below. Thiosulphate ions + Hydrogen ions Sulphur dioxide + water + Sulphur

3) The amount of acid

I believe this experiment will work because we have already done a preliminary experiment to check that this investigation will produce results for us to produce a table of results which we can analysis and form and evaluation from.

In the preliminary investigation we added a small amount of sulphuric acid to a solution of Thiosulphate the reaction that occurred was that the solution changed from a colourless clear mixture to a cloudy yellow solution approximately five seconds after we added the acid this showed that the experiment works and you can get results from it.

Method

) Collect the correct amount of Thiosulphate and other required substances such as the Sulphuric acid (distilled water)

2) Add the acid to the Thiosulphate solution.

3) Time with the stopwatch how long it takes for the water to go cloudy and the X marked on the piece of paper to become useable through the newly formed solution.

4) Repeat step 1 and add the correct amount of distilled water if required.

5) Repeat steps 2 and 3 and record the results into a table.

Results

The table below shows the results my group gathered after trying the investigation twice we recorded are results into this table and then worked out the averages for each concentration. We will use the Averages as are markers on the Graph.

Volume of Thiosulphate

Volume of Water

Time 1

Time 2

Averages

60

0

7

6

6.5

50

0

7

7

7

40

20

9

0

9.5

30

30

2

21

2

20

40

7

7

7

0

50

33

32

32.5

The measurements in the graph were all measured in cm3

Analysis

The Graph shows us that as the volume of the Thiosulphate decreased and the volume of the water increased it took longer for the reaction to occur. Proving that the main substance needed in this investigation is Thiosulphate, this is shown, as the time is less when there is less Thiosulphate to react with. For example, when the Thiosulphate is 50 cm3 and the Water is 10cm3 it takes 7 seconds to react. Whereas when the Thiosulphate is 20cm3 later in the investigation and the water is 40cm3 it takes 17 seconds over double the amount of time because of the lesser amount of the Thiosulphate. This is clearly shown in the graph, as the trend is a slopping line indicating the theory, and showing the concentration affects the time dramatically.

Conclusion

The results I recorded and plotted on the graph generally agree with my prediction they show the increase in the rate of reaction with the decrease amount of Thiosulphate,

Evaluation

The Experiment was a success as we managed to produce a very good range of results that can be seen above. The investigation gave us lots of results that we all close to the same, this gave us some indication of what we were looking for when we repeated the test. The results we got from repeating the test we similar and we were able to use these to get are average. When plotted on to are graph all the results are relatively close to the line of best fit showing we have no anomalous points. The method we used was time consuming but fair it allowed us to record the right amount of each substance and gave sufficient time to do the experiment. The method could have been inaccurate in a couple of ways the first of, which is the stopwatch as it is human, operated wouldn't have been precise. If we were to do the experiment again I would make sure that we used a couple of stopwatches each time and took the average reading. I would also do the experiment more than 3 times, as this would give us a more accurate measurement. All in all the investigation gave us a good set of results and was set up well this enabled us to get the best results possible and gave a greater understanding of chemical reactions to me.