The Simpsons is known for sprinkling math and science references throughout its scripts. (See Paul Halpern's book, right.) That's because many of the show's writers have advanced degrees in the subjects, including writer Bill Odenkirk, who has a Ph.D. in chemistry and George Meyers, who holds a degree in biochemistry from Harvard. In this episode, first aired last May, a math textbook gets shot and "bleeds" equations, and physicist Stephen Hawking makes an appearance in a flying wheelchair.
However, it turns out that the writers got this one wrong, as noted in this entry on tv.com:
When nitric acid & ethanol are mixed in this episode it produces a toxic gas. In fact, mixing these two chemicals will make a very explosive mixture, not a toxic gas.Or if you don't care to rely on chemistry facts from a TV website, here's a more reputable source.