Biology Lab Report
--------------- Testing the percentage of Vitamin C in different fruit juices

* Data collection

Raw data:

The Amount of Iodine used by Vitamin C in 10.0ml fruit solutions (ml) ± 0.01ml | Solution
Group
| Apple | Orange | Pitaya | Tomato | Pear | 0.05%Vitamin C solution | 0.1% Vitamin C solution | Group A | 0.25 | 2.66 | 0.42 | 0.82 | 0.36 | 3.16 | 6.13 | Group B | 1.34 | 2.96 | 0.41 | 1.02 | 0.27 | 3.01 | 6.24 |
Table 1

Processed data:

The average content of 0.05%vitamin C solution in both group A and B is: μ=3.16+3.012=3.085 ml

The average content of 0.10%vitamin C solution in both group A and B is: μ=6.13+6.242=6.185 ml

the average Iodine used in 0.01% vitamin C solution in both group A and B is: μ=3.0855+6.185102=0.618 ml

Therefore, next we have to calculate the average amount of Iodine used and the percentages of vitamin C in different fruit juice solutions by using the raw data and processed data above.

1. Apple juice solution:

The average amount of Iodine solution used is: μ=0.25+0.342=0.295 ml

The content of Vitamin C in apple juice solution is:
0.250.618+0.340.6182×0.01%=0.00477%

2. Orange juice solution:

The average amount of Iodine solution used is: μ=2.66+2.962=2.810 ml

The content of Vitamin C in orange juice solution is:
2.660.618+2.960.6182×0.01%=0.04547%

3. Pitaya juice solution:

The average amount of Iodine solution used is: μ=0.42+0.412=0.415 ml

The content of Vitamin C in pitaya juice solution is:
0.420.618+0.410.6182×0.01%=0.00672%

4. Tomato juice solution:

The average amount of Iodine solution used is: μ=0.82+1.022=0.920 ml

The content of Vitamin C in tomato juice solution is:
0.820.618+1.020.6182×0.01%=0.01489%

5. Pear juice solution:

The average amount of Iodine solution used is: μ=0.36+0.272=0.315 ml

The content of Vitamin C in pear juice solution is:
0.360.618+0.270.6182×0.01%=0.00510%

The content and percentage of Vitamin C in different types of fruit juices | 10.0ml Different juice solutions | Amount of Iodine solution (ml) ± 0.01ml | Percentage of vitamin C (%) | Apple | 0.295 | 0.00477 | Orange | 2.810 | 0.04547 | Pitaya | 0.415 | 0.00672 | Tomato | 0.920 | 0.01489 | Pear | 0.315 | 0.00510 | 0.05%Vitamin C solution | 3.085 | 0.05000 | 0.10%Vitamin C solution | 6.185 | 0.10000 |
Table 2

Graph 1

Relative Error =0.01ml ÷amount of Iodine solution
Absolute Error=Percentage of vitamin C contained in fruit juice×Relative Error

Error Analysis | | Relative Error | Absolute Error | Apple | 3.39% | 0.0152% | Orange | 3.55% | 0.161% | Pitaya | 2.41% | 0.016% | Tomato | 1.09% | 0.016% | Pear | 3.17% | 0.016% |
Table 3

* Evaluation

Conclusion:

As we can see from the tables and graphs above, the percentages of Vitamin C in various fruit juices is different. During our experiment, we can see that the Iodine solution can react with Vitamin C in different fruit juices and moreover, we can get a result that the more the iodine solution dropped into the juice, the will be more Vitamin C contained in fruit juices. By observing the graph above, we can conclude that orange juice contains the largest percentage of Vitamin C and apple contains the least percentage of Vitamin C among the five fruits used in our experiment.

Although the experiment resulted successful, there are still several problems that appeared along the experiment which can be improved in order to increase the accuracy of our experiment.

Limitations:

1. The first problem that led to the inaccuracy of our experiment: the various fruit juices we have used to do our experiment have already been put there for a while and there might be a loss of Vitamin C inside the juices. Therefore, this may cause the inaccuracy of our experimental result.

2. The second problem: It was actually hard for us to observe by eyes the changing of color of the starch, since every drop of Iodine solution is closely related to each other. Thus, the imprecise count of the Iodine solution used may cause inaccuracy.

3. Moreover, another problem that might due to the unclear of our experimental result was the beaker. We have used the same beaker for every fruit juices’ two groups. Since it was impossible to wash the beaker so clearly, this will cause a decrease in the accuracy of our result.