Effect of exposure - data

9. How to show that the experimentation was carried out as reported? (Evidence) Use of photograph, audio or video recording.

10. How to organize and present the data collected? (Results)

1^st experiment

Initial pH level of orange juice samples: 3.42

Constant temperature: 8°C (inside fridge)

Elapsed Time (hours)	pH Level of Orange Juice Sample (Covered)	pH Level of Orange Juice Sample (Exposed)
0	3.42	3.42
¼	3.43	3.50
½	3.45	3.56
¾	3.49	3.61
1	3.51	3.65
1¼	3.54	3.68
1½	3.56	3.71
1¾	3.58	3.72
2	3.59	3.72
2¼	3.60	3.75
2½	3.60	3.76
2¾	3.61	3.78
3	3.63	3.82

	Initial pH level	pH level at the end of 3h	Change in pH level	Percentage of change in pH (%)
Covered sample of orange juice	3.42	3.63	+0.21	+6.14
Exposed sample of orange juice	3.42	3.82	+0.40	+11.7

2^nd experiment

Initial pH level of orange juice samples: 3.29

Constant temperature: 8°C (inside fridge)

Elapsed Time (hours)	pH Level of Orange Juice Sample (Covered)	pH Level of Orange Juice Sample (Exposed)
0	3.29	3.29
¼	3.31	3.37
½	3.35	3.42
¾	3.38	3.47
1	3.40	3.51
1¼	3.42	3.54
1½	3.45	3.58
1¾	3.46	3.61
2	3.50	3.65
2¼	3.51	3.68
2½	3.53	3.72
2¾	3.56	3.73
3	3.58	3.75

	Initial pH level	pH level at the end of 3h	Change in pH level	Percentage of change in pH (%)
Covered sample of orange juice	3.29	3.58	+0.29	+8.81
Exposed sample of orange juice	3.29	3.75	+0.46	+14.0

11. What do the data mean? (Data Analysis)

From both experiments, we can see that the pH of both samples of orange juice increase over time. However, the pH of the exposed samples of orange juice increase at a faster rate than the covered samples of orange juice. There is also a greater change (increase) in pH levels of the exposed samples of orange juice at the end of 3h compared to the covered samples. In the first experiment, the exposed sample of orange juice experienced 5.56% more increase in pH compared to the covered sample. In the second experiment, the exposed sample had 5.19% more increase in pH than the covered sample.

This increase in pH level shows the rate at which the vitamin C content in the orange juice is degrading. This shows that vitamin C degrades faster in orange juice when the juice is exposed to air. Also, since there were no other affecting factors to the change in pH level of the orange juice aside from exposure to air, and the experiment was repeated and achieved similar results, it is safe to say that it is fairly accurate.

12. What can you deduce from the discussion of your data analysis? (Conclusion)

With this set of data, I can deduce that exposure to air affects the degradation of vitamin C in orange juice. The more the exposure to air, the faster the rate of degradation of vitamin C in orange juice. This also means that the lesser the orange juice is exposed to air, the better the retention of vitamin C, therefore proving my hypothesis right.

Effect of exposure - 2nd experimental plan

I made some changes to the experimental procedure as I felt there were some things that could have been improved on.

New procedure:
Step 1: Squeeze fresh orange juice, enough to fill one whole cup.
Step 2: Take initial pH level of orange juice and record it down.
Step 3: Pour orange juice equally into 2 plastic cups.
Step 4: Immediately cover the top of 1 cup with aluminum foil and cling wrap, and leave the other cup uncovered.
Step 5: Put both cups of orange juice in the fridge.
Step 6: Leave setups inside fridge for 3 hours and record the pH level of the juice every 15 minutes with the help of the data logger and pH probe.
Step 7: Construct a table for each set of data and then plot separate graphs of pH level against time.
Step 8: Repeat entire experiment once more.

Firstly, I decided to do both setups concurrently so that the initial pH levels of both setups would be the same. Using different oranges for both setups could have resulted in different pH levels for both samples of juice. Having same initial pH level will allow the data collected to be easier to analyse, easier to observe the difference in changes in pH level of both setups.

Secondly, I decided to record the pH level every 15 minutes instead of every 30 minutes so that there will be more data recorded, allowing us to observe in more detail on how the pH level changes.

Thirdly, I decided to repeat the entire experiment once more to ensure the accuracy of my results.

Effect of exposure - 1st experimental plan

1. What do you want to find out? (Aim/Purpose/Research question)
The effect of exposure to air on the retention of vitamin C in orange juice.

2. What is the tentative explanation of your research question? (Hypothesis)
The lesser the orange juice is exposed to air, the better the retention of vitamin C.

3. In an investigation, there is only one variable to be changed. Which variable will you change in this investigation? (Independent variable)
Exposure of the orange juice.

4. All the other variables must be kept constant. What are a few important variables that will affect the results greatly? (Constant variables)
- Type of orange juice
- Amount of orange juice
- Time taken (for experiment)
- Temperature
- Material of container
- Size of container

5. What results will you measure? (Dependant variable)
The pH level of the orange juice.

6. What are the materials and apparatus that you will need to carry out the investigation? (Materials and apparatus)
- Freshly squeezed orange juice
- 2 plastic cups
- Aluminum foil
- Cling wrap
- Data logger with pH probe

7. What are the steps that you will take to carry out the investigation? (Procedure)
Step 1: Squeeze fresh orange juice, enough to fill half a cup.
Step 2: Take initial pH level of orange juice and record it down.
Step 3: Pour orange juice into a plastic cup and immediately cover the top of the cup with aluminum foil and cling wrap.
Step 4: Put the cup of orange juice in the fridge.
Step 5: Leave setup inside fridge for 3 hours and record the pH level of the juice every ½ hour with the help of the data logger and pH probe.
Step 6: Construct a table for the data and then plot a graph of pH level against time.
Step 7: Repeat step 1 and 2.
Step 8: Pour orange juice into cup and leave the top uncovered.
Step 9: Repeat steps 4-6.

8. How are data collected? (Data collection)
Data is collected with the data logger and pH probe. This device records the pH level of the orange juice at my chosen time and allows me to see the change in pH of the orange juice samples. By observing the pH change in the juice, I am then able to determine which condition best allows the retention of vitamin C, as vitamin C is ascorbic acid. The increase in pH level of the juice – both covered and not covered over time will show me how fast the vitamin C in each sample of orange juice is degrading. The orange juice sample that is covered will have less exposure to air while the sample that is not covered is constantly exposed to air throughout the entire duration of my experiment. This will then allow me to prove or disprove my hypothesis that the lesser the exposure to air, the better the retention of vitamin C in the orange juice.