Chemistry Review

     In class today we did a review of basic chemistry, such as the octet rule, ionic and covalent bonding, and the lewis dot structure. I did a Making Molecular Models worksheet with a partner which emphasized atomic bonding and the octet rule. The octet rule is a rule that states that elements all prefer to bond in a way that can allow them to have eight electrons in their outermost shell. The electrons in this outer shell are known as an elements "valence electrons" and are the electrons that are taken away or are added to during bonding. We also reviewed polar and non polar bonds, and had to name which compounds are polar, for example H2O is polar, but H2 is not. Basic chemistry is important to learning biology because everything is made of chemical compounds, and understanding those will lead to a deeper understanding of Biology.

Dancing Milk Experiment

     Today in class we did an experiment in which we put drops of food coloring in a tray of milk, and then added detergent to see what would happen. Before we began we drew a hypothesis of what would happen with the help of our partner. Our picture depicts the detergent breaking up the fat molecules in the milk to allow the food coloring to spread.

Our drawn hypothesis

     After we drew our hypothesis, we began our experiment. My partner and I decided to have milk as the independent variable, and the dependent variable was how long the food coloring continued to spread for. We kept the number and color of the dye the same, as well as the type of detergent and the amount of detergent used. We used four types of milk, 2%, skim, whole, and soy, and put 15 ml of each in petri dishes. We then added three drops of red food coloring. 

Skim milk before adding detergent 

2% milk before adding detergent

     After this we added a drop of Ajax detergent with aloe and began timing the reaction.We first timed Skim milk, which had a reaction time of 40 seconds. Next we timed 2%, which had a reaction time of 45 seconds. Then we timed whole milk, which had a reaction time of 1 minute and 26 seconds. Finally, we timed soy milk, which had a reaction time of 1 minute and 32 seconds. 

Skim milk after adding detergent

     When we were finished with the experiment, we learned what actually happened in the experiment. Detergent is a surfactant, which means it is bipolar. The detergent works to break down the surface tension of milk by breaking up the H2O bonds. After these bonds are broken down, the food coloring is allowed to spread.