Sciencemadness Discussion Board

Plastic Sulfur Questions

subsecret - 8-6-2013 at 21:06

Earlier, I was melting some sulfur to do the classic "plastic sulfur" experiment. Once it melted, my lab filled with a pungent odor even though no fumes were visible. Is sulfur capable of reacting with oxygen to form SO2 just above its melting point? Any help is appreciated.

chemcam - 8-6-2013 at 21:19

What were you melting the sulfur in and how were you heating it?

When asking questions please give as much information as you possibly can.

[Edited on 6-9-2013 by chemcam]

AndersHoveland - 8-6-2013 at 22:54

How are you melting it?

Various investigators have reported spontaneous ignition temperatures for molten sulfur in air which vary from 232°C to 260°C. At 160°C, sulfur can form flammable vapor. So if you are heating with a flame, the vapor could possibly carry ignition back to the molten sulfur. This could be very difficult to see, since the flame from sulfur can be almost invisible, particularly with a quick vapor flash.

Hexavalent - 9-6-2013 at 00:32

I'll never forget one chemistry lesson at school where we were differentiating between the properties of metals and non-metals, which involved heating sulfur in a crucible strongly with a Bunsen burner. It sure melted into an orange liquid, but we had 30 small sulfur fires, each spewing off SO2 into the open lab :-P

Fantasma4500 - 9-6-2013 at 02:33

so basically you might wanna cover it up so it cant get oxygen to burn..
i have an idea for you if you wanna see the actual fumes or where theyre coming from..
suspecting theyre coming from the (beaker?) youre heating it in you can hold a bottle of NH4OH next to it and squeeze it gently
the NH3 is quite heavy and will sink down into the (beaker?)
the SO2 fumes will react forming a white smoke
also this will remove the SO2 from the air but it also looks pretty neat

subsecret - 13-6-2013 at 07:12

I was heating it in a glass test tube with a Bunsen burner. I think the ignition hypothesis is the most likely. Thanks for the help.

DraconicAcid - 13-6-2013 at 09:20

When sulphur burns in air, it tends to be a tiny little blue lame that is very hard to see. I've had dozens of students ignite their little puddles of sulphur, and they never notice the flame until their dish is placed into the fume hood and the flames fanned.

Eddygp - 13-6-2013 at 11:49

Quote: Originally posted by DraconicAcid  
When sulphur burns in air, it tends to be a tiny little blue lame that is very hard to see. I've had dozens of students ignite their little puddles of sulphur, and they never notice the flame until their dish is placed into the fume hood and the flames fanned.

Or until they involuntarily poke a finger in or next to it and scream a bit... (like me, the first time I worked with it without noticing)

DraconicAcid - 13-6-2013 at 12:03

That particular course may be full of students with very little comprehension of chemistry, but at least I've never had anyone poke their burning sulphur with a finger. But it's on a ceramic well plate that they've been basting with a Bunsen burner, so they should find it obvious that they should keep their fingers out of it.


I've probably just jinxed myself, haven't I?

Eddygp - 13-6-2013 at 12:29

Quote: Originally posted by DraconicAcid  
That particular course may be full of students with very little comprehension of chemistry, but at least I've never had anyone poke their burning sulphur with a finger. But it's on a ceramic well plate that they've been basting with a Bunsen burner, so they should find it obvious that they should keep their fingers out of it.


I've probably just jinxed myself, haven't I?

Well, I obviously did it without noticing, because I knew that it was going to be quite hot anyway.

Tdep - 13-6-2013 at 16:00

Oh god the memories...

annaandherdad - 14-6-2013 at 07:09

Quote: Originally posted by Antiswat  

the NH3 is quite heavy and will sink down into the (beaker?)


?? NH3 is lighter than air.

subsecret - 14-6-2013 at 21:03

I could use ordinary CO2 as an "inert" gas. I have a pressure-equalizing addition funnel (specifically for gas generation) that I frequently use. Due to a lack of proper equipment, I drip HCl from the funnel into a solution NaHCO3 in a one-neck round-bottomed flask. I place a gas adapter in the top of the addition funnel (the CO2 flows through the pressure-equalizing arm and through the adapter). This might be a tangential question, but does this method result in excessive HCl gas being carried along with the CO2?

Finnnicus - 14-6-2013 at 21:14

If you use a diluted HCl solution, you shouldn't have a problem, anything upwards of 25% fumes quite steadily.