2. Methods


2.1 Equipment
- Oranges x 36
- Beakers 80ml x 4
- Measuring Cylinders 100ml x 3, 250ml x 1
- Juicer x 1
- Conical Cylinder 250ml x 1
- Starch Solution x 500ml
- Iodine Solution x 500 ml
- Disposable Droppers 3ml x 5
- Funnel x 2
- Knife x 3
- Tiles x 3
- Pestle and Mortar x 1
- Vitamin C tablets 250mg x 10
- Table lamp x 1
- Refrigerator x 1
- Disposable Gloves x 1 box
- Distilled Water x 2L

2.2 Diagram
Fig. 1. Titration process of orange juice from the orange.
Fig. 2. Titration process of vitamin C solution (control)

2.3 Procedures
1. Store 36 oranges into each of the 3 different places, 12 in each location.
a. Near a heat source (i.e. beside a window with a table lamp shining on it, temperature: average temperature 27.5℃)
b. In a place with constant temperature (i.e. in a cupboard, temperature: average temperature 26℃).
c. In a place that is just above 0 degree Celsius (i.e. in the refrigerator: average temperature 5℃).
2. The oranges and the control solution will be tested daily using the testing methods.
3. The results from the daily testing will be keyed into a spreadsheet daily.
4. At the end of two weeks, the result will be compared with each other and the daily decrease will be calculated.
5. From there, a conclusion will be made and a report will be generated to see whether the hypothesis is correct and figure out which is the ideal place to store oranges.

To make control solution (to be made freshly everyday)
  1. Grind a 250mg Vitamin C tablet into fine particles.
  2. Add 100ml of water and mix thoroughly, until the solution becomes a homogenous mixture.
  3. Add another 150ml of water to dilute the solution and mix thoroughly.

To titrate control solution
  1. Measure 20ml of control solution into a beaker/measuring cylinder.
  2. Add 10 drops of starch solution
  3. Using a disposable dropper, measure the amount of iodine solution and add into solution drop by drop into the flask.
  4. Swirl the flask to mix the iodine solution and the juice solution after each addition.
  5. The titration will be complete when the iodine creates a blue-black colour in the solution that lasts for more than 20 seconds.
  6. Measure the amount of iodine solution added into the control solution and record down.

To titrate orange juice
  1. Measure 20ml of juice into flask
  2. Add 10 drops of starch solution
  3. Using a disposable dropper, measure the amount of iodine solution and as into solution drop by drop into the flask.
  4. Swirl the flask to mix the iodine solution and the juice solution after each addition.
  5. The titration is complete when the iodine creates a distinct colour change in the juice solution. The colour of the end product of the titration of the orange juice solution would be more greyish compared the the colour of the end product of the titration of the vitamin C control solution. The colour will change from orange to grayish brown when the endpoint is reached.
  6. Measure amount of iodine added into the juice solution.

2.4 Risk Assessment and Management
List / Identify the hazardous chemicals, activities or heat devices that will be used
  • Iodine solution will be used in the experiments. Iodine itself is poisonous
  • Oranges have to be cut to obtain the juice which will be tested on.
  • Glass beakers and other lab equipments will be used throughout the experiment.
Identify and assess the risks involved
  • If not handled properly, one can be poisoned by the iodine solution
  • If not handled properly, one can injure himself/herself because of the blade’s sharpness
  • If not handled properly, one can injure himself/herself by the glass once the beaker or any other equipment is broken/shattered.
Describe the safety precautions and procedures that will be used to reduce the risks
  • To prevent Iodine poisoning, gloves and lab safety goggles will be worn at all times.
  • To prevent injuring oneself with a knife, peer supervision will be made and an there will be First-aid kit available in the lab so that help can be easily rendered in the case of one getting injured.
  • To prevent injury from broken glassware, we will wear gloves and take caution while using the glassware.

2.5 Data Analysis

A spreadsheet will be used, where results of the experiment conducted everyday over the period of two weeks will be recorded. At the end of two weeks, a comparison between all the data we collected will be made. Since only the rate at which Vitamin C decreases will be compared, no software will be needed. After the spreadsheet is completed, graphs will be created manually based on the place that the orange was stored in. our data will be represented in the form of a bar graph.

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