By: Bidemi Oladiran (AmeriCorps VISTA)
The Harford Hills elementary after-school STEM program concluded on March 15th, 2016. The programs final lesson continued with topics on science and engineering taught by Ms. Nia Fields and I. The fourth and final lesson encouraged students to reduce their carbon footprint by doing an experiment. The first experiment involved using 0.04% Bromothymol blue (BTB) which is a chemical solution that detects if something is acidic or basic. In the first experiment students blew bubbles in a cup of water containing one drop of BTB which was originally light blue from the solution. The more the students blew bubbles, the more carbon dioxide (CO2) was produced which resulted in a yellow color change. The second experiment consisted of filling a plastic bag with water after ensuring all the air was pressed out and adding ½ a tablet of antacid to the bag, along with 2 drops of BTB. The solution turned a darker yellow. The more CO2 there was the more acidic the solution became and the solution turned into darker yellow. The students were fascinated by this but their fascinating wouldn’t end there.
The third experiment involved using various types of milk from low fat milk like skim, 1%, and 2% to high fat milk like whole milk and cream. The students used a cotton swab dipped in dish soap to show how chemical bonds are weakened. The various milk were poured in a small aluminum pan, a drop of each color yellow, green, red and blue were placed in different places on the milk. Afterwards, the students gently placed the tip of cotton swab covered in soap onto the surface of the milk creating a swirl of rainbow colors in the milk. In actuality, what happened was that the dish soap was bipolar and the polar/hydrophilic/water-loving end dissolved in water while the non-polar/hydroph
obic/water-fearing end attached to the fat portion of the milk, bending the fat molecules causing them to “roll, twist and contort in all directions” thus resulting in the various rainbow colors seen.