Summer SAVY 2016 (Session 3, Day 4) – Chemical Spill
Today in Chemical Spill! we learned about an oil spill that happened off of the coast near Santa Barbara, CA. We discussed how the oil did not mix with the water because oil is hydrophobic, i.e. “water fearing,” whereas substances that dissolve in water are hydrophilic. We also learned how the density of materials determines whether they float or sink; given that oil has a lower density that water, it floats. The students also used a density table to explain why other phenomena occur, for example, why metals tend to sink in water and why we fill balloons with helium. In order to synthesize our understanding of hydrophobicity/hydrophilicity and density with knowledge from previous days, we created a “lava lamp” using baking soda, oil, and colored vinegar. Ask your student to explain what they observed and how the lava lamp works.
Next we discussed various ways to clean up an oil spill. We also spent a good deal of time discussing dispersants (also called surfactants), learning how they work by having both a hydrophilic “head” that can interact with water and a hydrophobic “tail” that can interact with oil. The students especially seemed to enjoy discussing surfactants in the context of detergents used to clean birds affected by the spill . . . it’s hard not to like Dawn commercials with cute rescued animals! In the afternoon, the students tried three different methods to clean up an oil spill, including the use of skimmers, sorbents, and dispersants. As a group, we assessed the pros and cons of each method and there was quite a lively debate as to which method(s) would prove effective in various contexts. I encourage you to discuss with your student his/her rationale for which method they thought would work best.
I also encourage you to attend the open house tomorrow, which will occur from 3:15-3:45 PM. The students will be demonstrating some of their favorite experiments and are looking forward to showing you what they have learned.
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