Say I get a sheet of paper and place it in a laboratory vacuum. I then aim a laser at it and heat the paper until it reaches 451 degrees Farenheit. What happens to the paper?
Sua
It might char a little but wouldn’t burn without a source of oxygen. An inert atmosphere might work as well and displace more oxygen. I think it would be simlar to the process of making coke by heating coal in the absence of oxygen.
Stop it. We know what you are trying to do. You can’t trick the firemen, and really shouldn’t try. They will be here shortly, so you’d better be moving on.
-an anonymous friend-
I’d like to take a WAG at this one.
First off, the 451 deg F number is meaningless because that’s the ignition point of paper in air. But if you heat it enough, something will happen.
If you heat anything in a vacuum it tends to decompose into its elemental constituents. IIRC, paper is made from hydrogen, oxygen, and carbon. Even the carbon will vaporise
if the vacuum is low enough and the temperature high enough. The liberated oxygen and carbon could indeed form
CO2, i.e. burn. However, if you kept the vacuum at about 1E-2 torr, and the temp around 1100 deg C, it will be well above the vapor pressure of carbon. In that case you will end up with a small pile of carbon on the furnace floor, while the O2 and H2 go out the vacuum pump exhaust.
OTOH, at this temp and pressure, if you wrap the paper around a suitable substrate first, there’s a good chance the carbon will plate out as diamond. Pressure doesn’t make diamonds; heat and the absense of O2 do.
You can just about duplicate this in a test tube, you don’t need to put it in a vacuum. It is called distillation, or at least it was when we did it with popsicle sticks in high school.
We put the sticks in a test tube oriented horizontally with a rubber stopper with a single hole, and a hose going to a second test tube with a stopper with two holes. The second test tube was oriented vertically and sat in a cold water bath. One hole connected with the original test tube and the other hole had a hose going into an inverted jar in a tub of water, which had no air in it.
What we got was a test tube full of carbon/charcoal, a test tube full of methanol, and a jar full of methane.
I would imagine that paper would give you similar results.
You wouldn’t get a flame, but you sure would get a reaction. Maybe not at 451 degrees as TNT mentioned, but you’d get a reaction.
Wasn’t the “fact” that paper burns at 451 degrees Fahrenheit just made up by Ray Bradbury for his novel?
Previous posters have gotten it right…you’ll end up with charcoal. If you opened up the vacuum to atmosphere while this process was going on (still hot inside the chamber, enough gasses remaining), you would get a backdraft. If you let the chamber cool off before you opened it up, then you’d get a pile of charcoal.
Paper burns at 506 Kelvins, or 451 F.