Most people are familiar with the idea that oil and water do not mix. Crude oil is a complex mixture of mostly very long chain alkanes. During the refining process, the long alkane chains of crude oil are broken into shorter chains using heat and catalysts, then purified by distillation at refineries on the basis of boiling point into fractions such as gasoline (boiling point fraction between 100°C and 400°C) or diesel fuel (boiling point fraction between 180°C and 360°C). During the Deepwater Horizon oil rig disaster a little over two years ago, between 17 and 39 million gallons of crude oil spilled into the Gulf of Mexico. Thousands of birds, turtles and sea mammals died because they were covered by oil. Well over 125 miles of coastline were affected. The major cause of the destruction is that the oil was not simply diluted by sea water, but rather, it floated on the surface in large slicks that were blown by prevailing winds until they reached a shore. What is worse, animals that need to breath air such as turtles and sea mammals (dolphins, whales, manatees) became trapped under the oil slick and had to surface into it to breathe, sealing their doom. Unsuspecting birds landed on the surface of the oil slick, becoming covered in sticky oil that prevented them from flying away.
Why does oil float on the surface of sea water rather than sink to the bottom?
A. Oil is less dense than water primarily because crude oil is mostly -CH 2- chains while water is H2O and O has a higher atomic number than C.
B. Oil is less dense than water primarily because crude oil is mostly -CH 2- chains while water is H2O and O has a lower atomic number than C.
C. Oil is less dense than water primarily because water molecules cannot pack together as well as the crude oil molecules pack together.
D. All of the above.
The long chain alkanes of crude oil stick to each other largely through interactions that can be described as the following:
A. London dispersion forces.
B. Attraction between induced transient dipoles associated with temporary fluctuations in electron clouds around the molecules.
C. Hydrogen bonding
D. Both A and B