Sunscreen soap and UV radiation
The materials required for this science fair project:
- 5 glass sheets measuring 500mm x 500mm
- 1 UV meter to measure UV index
- 1 wooden box with open top (approximately 500mm length x 500mm width)
- 500 ml alcohol
- 250 gram of glycerin
- 10 gram of Octyl salicylate
- 5 beakers
- 1 measuring cylinder
- 5 sponges
- 1 spatula
- 1 digital weighing scale
1. For this science fair project, the independent variable is the concentration of Octyl salicylate in the soap solution. The dependent variable is the level of the UV index measured. This is determined with the UV meter. The constants (control variables) are the time the readings are taken, the intensity of sunlight and other weather conditions on the day of testing and the location where the testing is done.
2. The 5 sheets of glass and 5 beakers are labeled as 0%, 2%, 4%, 6% and 8%. Using the measuring cylinder, 100ml of alcohol is poured into each beaker. 50 mg of glycerin in also added to each beaker.
3. In the beaker labeled as 0%, no Octyl salicylate is added. In the beaker labeled 2% - 1 gram Octyl salicylate, 4% - 2 grams Octyl salicylate, 6% - 3 grams Octyl salicylate and 8% - 4 grams Octyl salicylate is added. The solution is mixed using the spatula.
4. Using separate sponges, the soap solution in the beakers is spread evenly over the glass surface according to the labels, and allowed to dry.
5. The wooden box is placed in a location where it receives direct sunlight without any obstruction or shadows. The UV meter is placed inside the box and the UV index reading is taken. The reading is recorded in the table given below.
6. The glass sheet with the 0% marking is placed over the box with the UV meter still inside the box. The new UV index is observed and recorded in the table given below.
7. Procedures 5 and 6 are repeated using the glass sheets with 2%, 4%, 6% and 8% markings. All of the UV index readings before and after placing the glass over the box are observed and recorded in the table given below.
Avoid long, unprotected exposure to the sun. Handle glass extremely carefully. Adult assistance required.