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May20-10, 07:32 PM
P: 274
Quote Quote by Q_Goest View Post
Hi gwangi,

Interesting question. Petroleum is of course, a mixture of various hydrocarbons, and I have no idea what hydrocarbons are being released but I suspect it is fair to say they are relatively heavy with carbon chains in the neighborhood of 15 to 25 carbons. Let's assume the carbon chains follow the general rule CnH2n+2 and look at a couple of different hydrocarbons at 2500 psia and 40 F. There are reports of tar balls washing ashore, so I'll include an even heavier hydrocarbon. Here's what the density looks like:
C16H34: 34 lb/ft3
C24H50: 50 lb/ft3
C30H62: 52 lb/ft3

From this, it looks like these hydrocarbons are less dense than seawater, so they should come to the surface. Why is there a layer of these hydrocarbons reported deep under the surface? I don't know...
The temperatures and introduction of dispersants have been implicated, but it is still uncertain. There seems to be the range from "sheen" to "tar" and the mayonnaise-like slick in between. Hopefully congress will demand a public analysis of what BP is siphoning so we can have a better idea of how to answer these questions. The disaster has occurred, we must at least learn from this.