The character Quinton tries to create a rocket fuel...
" Potassium chloride has a potassium atom. If we mix it with sugar and add heat... we'll get three parts oxygen, two parts carbon dioxide...along with some other by-products. In other words, lots of good expanding gases."
...he washes it down a sink, the another student puts a flame down her sink. All the sinks in the classroom spirt out a huge flame
Can this really happen?

I am not sure on the mixture, you would have to see the movie.

But I did get a direct quote

I doubt if "rocket candy" (the sugar and an oxidizing agent) mixture would give off flammable vapors but being in a chemistry classroom, I wouldn't be surprised if other groups or classes may have poured flammable liquids down the sink drain.

Although in my own high school chemistry class, we would be instructed where to dispose of chemicals after our labs. Some were allowed down the drain but others had to be collected in a special "Inorganic waste" drum that our instructor would roll into the front of the class. But, you know, some kids would ignore the instructions and pour it down the sink anyway.

Exactally, so maybe the myth is plausible given the right conditions?

In the book by Homer Hickam, Jr.,Quentin, after being told by Homer that their teacher would not give them the potassium chlorate says: "That's O.K. potassium nitrate has much the same property and exactly the same number of oxygen atoms as potassium chlorate. Mix saltpeter and sugar and we should get the same result."

Then he goes on to say about the same thing as you said, except he says: "Potassium nitrate. KNO3. The same as potassium chlorate except it has a potassium atom instead of a chlorine one.

And: "I think that if we mix it with sugar and add heat we'll get three parts oxygen and two parts carbon dioxide along with some other byproducts. In other words, lots of good expanding gasses. It should be an excellent propellant."

The next line is : Quentin looked to be right. "I'll test it tonight," I promised.

I could not find in the book where Quentin mixed it up in class.

I think it was added to the movie, and was not true to the book.

Oh really, I have not read the book before, so I don't know, but I wonder if different chemicals will make a huge difference in whether the sinks spirts out the flame or not?

quote:

I wonder if different chemicals will make a huge difference in whether the sinks spirts out the flame or not?

If Quentin washed it down the sink, I would think that the chemicals would be wet because of the water, and would not ignite.

In the book, Homer tested it by tossing some into their coal-fired water heater and watched it "Poof."

Quentin said that the sugar was too soluble, and had too much moisture when they used it dry,and they finally got it to work well by melting it together and pouring it into their "casements."

The book is much more detailed than the movie, and you should get a copy.

Oh, and the book is titled: "Rocket Boys", not "October Sky," like the movie was.

The book sounds very good. Maybe the water reacted different, but you are probably right.

Is there a mixture that can "poof" with water added?

The water would probably effect the outcome drastically.

quote:

Is there a mixture that can "poof" with water added?

I'm not a chemist by any means,and I'm sure some of the other members can think of other things, but I have been thinking about this and can't come up with any.

The only thing that crosses my mind that might be similar is calcium carbide and water.

When mixed, Acetylene gas is produced, and we know that burns quickly.

Small cannons are made that use Carbide and water to produce the gas, and when ignited make a loud boom.

Maybe that would work! I am not an expert either, but that sounds like it could work. The explosion in the film was a "poof" of fire and did not make a loud sound though.

I wonder if the sinks were a big element in this too

I remember from my high school chemistry class, the equipment which were about the same age as the one in October Sky, we were told that some chemicals could not be disposed of in the sinks because they had some kind of drain system where each of the stations would drain to the same pipe.

That really helps the myth