- Instead of using orange juice, now apply the orange squash to steps 1-3 instead of ascorbic acid and fresh orange juice. All the apparatus used and amount of solutions used MUST be kept constant, except for the change to Robinsons orange squash. This is essential in order to achieve a fair test and accurate experiment. Record results for all three test tubes.
Make sure to measure out the quantity of the solutions as accurately as possible, and do not mix any of the solutions up. Also, when applying solutions to the DCPIP solution, make sure to apply them one drop at a time, as if you just pour the different solutions into the DCPIP solutions, the DCPIP could have already decolourised, and you wouldn’t know, therefore making you apply TOO MUCH of one solution, altering the results and therefore making this experiment not fair nor accurate.
This is also why it is essential to use the same apparatus at all times, with the same amounts, but different solutions for each test. Fair testing is extremely important, especially in this type of experiment, with accuracy being an equal priority.
Apparatus:
- 3 Syringes
- 10 cm3 of DCPIP solution
- 5cm3 of Ascorbic acid solution
- 5cm3 of Orange Squash
- 5cm3 of Fresh Orange Juice
- 9 Medium size Test Tubes
Results:
After conducting this experiment, I have obtained the results for all three tests, with three results and an average for each test, in order for me to identify how much Vitamin C there is in fresh orange juice and orange squash, and which liquid has more. In order for me to calculate the amount of Vitamin C there is in the fresh orange juice, the fresh orange squash, and the ascorbic acid, I must have knowledge of the amount of each solution needed to completely decolourise the DCPIP solution. The following is a results table to show this, along with the average amount for all three liquids, in cm3:
Results Table:
The results above show that more orange squash was needed in order to decolourise the DCPIP solution than the orange juice. Only an average of 0.54 cm3 of orange juice was needed to decolourise the DCPIP solution, and a rather greater average of 2.6 cm3 of orange squash was needed. So orange squash needed 2.5 cm3 more in order to decolourise the DCPIP solution. Also, it took an average of 0.3 cm3 of ascorbic acid in order to decolourise the DCPIP solution. This particular result is very important as it leads to the calculation of how much Vitamin C content each liquid actually has.
The results were taken 3 times for each liquid, in order to obtain the average amount of each liquid needed to decolourise the DCPIP solution. In doing this, I was able to conduct an accurate and fair experiment, in order for the experiment to be as accurate as possible, and for the results to be ‘truthful’, and fair. This was essential in order to conduct this experiment successfully, and for no mistakes to be made, otherwise this experiment would just be a waste of time.
The volume of ascorbic acid needed to decolourise 1cm3 of DCPIP solution is 0.3cm3. In the first test, the volume of orange juice needed to decolourise 1cm3 of DCPIP solution is 0.55 cm3. However, as the experiment was repeated three times for both orange juice, and orange squash, the average volume of orange juice and orange squash needed to decolourise 1 cm3 of DCPIP solution is the following:
Orange Juice:
Average (cm3) = 0.55 + 0.53 + 0.54 = 1.62 = 0.54 cm3
- 3
Orange Squash:
Average (cm3) = 2.4 + 2.8 + 2.6 = 7.8 = 2.6 cm3
- 3
Ascorbic Acid:
Average (cm3) = 2.5 + 3.0 + 3.5 = 9.0 = 3.0cm3
3 3
So the average amount of orange juice needed in order to decolourise the DCPIP solution is 0.54 cm3, and the average amount of orange squash needed to decolourise the DCPIP solution is a rather higher 2.6 cm3, and a much higher 3.0 cm3 of ascorbic acid to carry out the decolourisation of the DCPIP solution.
The following is the calculation of how much Vitamin C each liquid contains, and which liquid, orange juice or orange squash, has the most Vitamin C:
Calculation:
The ascorbic acid contains 1mg of ascorbic acid per cm3, so:
The orange juice contains = 1 x Volume of ascorbic acid needed
Volume of orange juice needed
= 1 x 0.3
0.54
= 0.56 mg/cm3
As the ascorbic acid contains 1mg of ascorbic acid per cm3:
The orange squash contains = 1x Volume of ascorbic acid needed
Volume of orange squash needed
= 1 x 0.3
2.6
=0.12 mg/cm3
The results show that the orange juice contains 0.56 mg/cm3 of Vitamin C, whilst the orange squash contains a far less 0.12 mg/cm3 of Vitamin C, in fact, 0.44 mg/cm3 of Vitamin C less than the orange juice. This result has proved my prediction to be correct, and shows that this experiment actually was a fair and accurate one.
On the following page is a bar graph to show these results, and to show how much more orange juice has in Vitamin C than orange squash, and to explain the findings in a more detailed manner, with the X- axis labelled as the ‘Type of Liquid’, and the Y- axis labelled as ‘Amount of Vitamin C content in each liquid, in mg/cm3’.
Conclusion:
The results show that the orange juice contains more Vitamin C content than the orange squash, as the size of the bars shows exactly this. In fact, this bar graph shows that the orange juice has a considerable amount of Vitamin C more than the orange squash, in fact, 0.44 mg/cm3 more than the orange squash. Again, as I have said, these results have proved my prediction to be correct, and so making this experiment a rather fair and accurate one.
As there are no sudden changes to the results, such as a far greater amount more than the second or third result in the DCPIP decolourisation test, this also proves that this experiment was well coordinated and no major mistakes were made in the process of the findings of the results.
As it takes orange juice an average of 0.54 cm3 to decolourise the DCPIP solution, and it takes orange squash an average amount of 2.6 cm3 to also decolourise the DCPIP solution, this indicates that the orange juice needs less of itself in order to decolourise the DCPIP solution, meaning that the concentration of Vitamin C in the orange juice is stronger than the concentration of the Vitamin C in the orange squash, as less orange juice is needed in order to decolourise the DCPIP solution than the orange squash, meaning less effort needed for the process.
The orange squash however, needed quite more Vitamin C concentration in order to decolourise the DCPIP solution, as it needs more effort and more Vitamin C in order to complete the process of decolourisation.
The molecules of the orange juice need to diffuse the molecules of the DCPIP solution in order to decolourise the solution. In the process, the DCPIP solution turns firstly pink, then the colour eventually gets lighter and lighter, until a colourless solution of orange juice and the DCPIP occurs. This is when the DCPIP is diffused completely, and so turns into a decolourised solution. The molecules of the orange juice do not have to work so hard in order to diffuse the DCPIP molecules, and so only a small amount of orange juice is needed in order to decolourise the DCPIP solution.
And this is also the same for the orange squash. The molecules of the orange squash DO in fact need to work hard in order to diffuse the DCPIP molecules, and more orange squash is needed in order to successfully decolurise the DCPIP solution. The following are two diagrams to explain this very process easier:
If more orange juice or orange squash was added, then the results would be inaccurate, as we would not know when to stop adding each liquid to the DCPIP solution. This is why a syringe was used, and why each liquid was added to the DCPIP solution one drop at a time, so the results would be as accurate and fair as possible, in order to conduct this experiment successfully, and so the results would be correct, and so would the overall conclusion of the experiment, the most important part of this type of experiment.
And so, my overall conclusion of the experiment would be that orange juice contains more Vitamin C content than orange squash, doesn’t need as much effort and amount in order to decolourise the DCPIP solution. The diffusion of the DCPIP by the orange juice is easier, and the diffusion by the orange squash is much harder, bringing this experiment to a conclusion that:
The Orange Juice has a higher concentration of Vitamin C than the Orange Squash, and so has more Vitamin C Content than the Orange Squash.
Evaluation:
My results were very reliable in this experiment, and there was no evidence of any anomalous results, meaning that all my results were all suitable and according to plan. I used all the equipment required, and did not mix any of the solutions together. I did not use the same syringe for all the solutions, and carefully measured all of the readings, to the very decimal. I started off with the same amount of liquid, 1cm3, and then added each liquid, one drop at a time to the DCPIP solution until the solution COMPLETELY decolurised, leaving a colourless solution. I did NOT shake the solutions during the process at all, in order for the experiment to be as fair and accurate as possible.
As I have said, my results were very reliable, as I repeated the test for each liquid three times, in order for the experiment to be as accurate as possible, and for me to make sure whether I have missed something out or not, and to see if my results would fit in well, which it did, as the results came out as I expected, leaving the average to be very fitting.
I used the same amount of each liquid for every test in order for it to be a fair one, and for the experiment to be as successful as possible, and for the results also to be as reliable as possible, in order to find out the correct amount of vitamin C in each liquid, and to conclude this experiment correctly and accurately.
I think that the method used was extremely accurate and suitable for this type of experiment, and it was a good idea to record the results three times for each liquid, in order for the results to be as accurate as possible. The amounts of liquids used in this experiment were also very suitable amounts, as not too much was used, and not too little. This was a very important part of the experiment, and if different amounts were used, the experiment would eventually fail, and the results would be altered, the conclusion would differ, and my prediction would wrongly be incorrect. The warnings were very useful, and it was this that really took a great part of the success of this experiment.
However, there are some ways in order to improve this very experiment, even though everything worked out to be fine. Maybe, it would have been a good idea to not allow the liquid to be open to air, as this could cause Vitamin C content to be lost, although not very much, but maximum accuracy is a priority for this experiment.
Also, it would be a good idea to try to obtain pure orange juice and orange squash, rather than from companies, as the orange squash was produced by the company, ‘Robinsons’. Maybe in the process of making the orange squash, some Vitamin C content was lost, and so would not make this experiment to be fair, and the same for the orange juice used in the experiment. Another way to improve the experiment is for the juices not to be shaked, as this would also decrease the Vitamin C content in this experiment, leading to inaccurate and unfair results.
However, this experiment was a rather casual one, not a detailed scientific experiment, so these improvements would not really matter in a classroom experiment like this. But apart from these possible future improvements, the experiment turned out rather well, with accurate and suitable results, everything conducted to this experiment, nothing altered such as the liquid quantity, and the same size syringes, test tubes and beakers were used, making this experiment an accurate, fair, logical and a rather successful experiment.
