The Difference of Absorbencies in Physical and Chemical Sunscreens

This experiment was performed to determine if physical sunscreens absorbed more UVA rays and UVB rays than chemical sunscreens. The objective of the experiment was to make six sunscreen solutions and test their absorbencies. Each solution contained n-propyl alcohol and a specific type of sunscreen. Three of the sunscreens had a physical active ingredient with three different sun protection factors (SPF). The other three sunscreens had a chemical active ingredient with three different SPFs. We made five different dilutions of each of our solutions. The thirty dilutions were each placed individually in a UV-visible spectrophotometer and their absorbencies measured under rays of 320 nm and 360 nm. Two ANOVA standard of variance tests were used to interpret our data. The results of the ANOVA tests showed that there was a significant difference in the chemical and physical sunscreens under 320 nm of light and 360 nm of light. The hypothesis stated that if the absorbencies of physical and chemical sunscreens were measured in a UV-visible spectrophotometer, then the physical sunscreens would absorb more UVA rays and more UVB rays that the chemical sunscreens.  This hypothesis was accepted because there were significant results for both tests.

Research Done By:

Kaitlyn Bimberg
South Lake High School

Jillian Jablonski
Warren Mott High School