Sulfur and Saltpeter Candle

Sulfur is dropped into molten potassium nitrate. Deflagration ensues!

A spoonful of potassium nitrate is dropped into a test tube and heated with a propane torch until melted. A solid chunk of sulfur is dropped into the liquid salt and burns with a steady, bright flame and produces a large amount of gases.

Category:

Science & Technology

Tags:

• Sulfur
• saltpeter
• potassium
• nitrate
• dioxide
• test
• tube
• chemistry
• chemicals
• experiment
• fire
• deflagration
• burn
• oxidizer

[ReactionFactory]

In this reaction, it isn't the temperature that is likely to break the test tube, but the temperature differential. Those tubes are quite resilient, though. If you want the temperature where they would break with fully even, slow heating, I would have to conjecture that it would be the point where the borosilicate glass becomes too liquid to hold its shape.

[yellowmetalcyborg]

Could you have bubbled the SO3 through water to make sulfuric acid?

[ReactionFactory]

@yellowmetalcyborg

If you had the correct apparatus, and a way to be sure that there wasn't too much SO2, that would work, in theory. You would need very heat and shock resistant stoppers and tubing, and the sulfuric acid you would get would be very dilute. Boiling it down may work to concentrate it. See the following quote from Wikipedia:

[ReactionFactory]

@yellowmetalcyborg

"In the 17th century, the German-Dutch chemist Johann Glauber prepared sulfuric acid by burning sulfur together with saltpeter (potassium nitrate, KNO3), in the presence of steam. As saltpeter decomposes, it oxidizes the sulfur to SO3, which combines with water to produce sulfuric acid. In 1736, Joshua Ward, a London pharmacist, used this method to begin the first large-scale production of sulfuric acid."

[Phacias]

You should have ignited it!

[ReactionFactory]

@Phacias

We should have ignited what? It was already burning quite intensely on its own. Adding another flame would have done nothing.

[rgmcall]

@yellowmetalcyborg Ive tried that and ended up with sulfuric acid that smelled like rotten eggs the most you could boil it down to is 70 percent though

[zakamooza]

at what temperature does those test tubes break ? plz reply i have to know,

~in celcius

[yellowmetalcyborg]

@ReactionFactory Thanks.

I might just as well buy it, the costs of the reagents are far greater than that of the finished product.

Ahh well.

[MOTAofCC]

tada u have created molten glass:)

[vanadiumV]

@ReactionFactory so test tube made from space shuttle window glass ))

Pyrex glass

thanks again friend !!

[Phacias]

@ReactionFactory Actually, I posted a comment before it burst into flames. Sorry ;(