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Kevin Kolbe

How can I clean solid sulfur and its oxides from test tube?

Cooking Secrets  Follow

Since you stated:

I'm not a chemist, so I don't have any strange chemicals at home.

you will neither have facilities for their proper storage and waste management.

Consequently, the only reasonable solution is: Get some new test tubes (about 0.20 Euro for a 160 x 16 mm tube), but don't risk your own health or pollute the environment by messing around with carcenogenic ($\ce{CrO3}$ in $\ce{H2SO4}$) or neurotoxic ($\ce{CS2}$) agents.

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Edward Parmenter  Follow
If you were a chemist, and had the facilities and chemicals: Still dump that test tube.More
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Danu Novmanu  Follow

There are a couple of ways to do it depending on what chemicals are available to you. Since sulfur melts around $115~\mathrm{^\circ C}$, you might first melt it and let as much liquid drip out of the test tube as possible in order to make the following step easier.

  • Perhaps the most straightforward method involves toluene or xylenewhich you can probably purchase at a hardware store. Put sometoluene or xylene in the test tube and heat it up (note: be careful,toluene and xylene are flammable), the sulfur should slowly dissolve.Pour the waste liquid out while hot. Repeat the process ifnecessary. If you can find both toluene and xylene, pick the xylenebecause it has a higher boiling point - it can get hotter anddissolve the sulfur better.
  • Chromic acid (sulfuric acid and potassium dichromate) will remove sulfur. Pour the chromic acid into the test tube and let it sit for a couple of days, then pour it out, and with the help of a spatula, you should be able to remove the sulfur as a solid chunk.
  • Carbon disulfide dissolves sulfur, but $\ce{CS_2}$ is toxic and extremely flammable

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Glen James  Follow
The chrome VI species in cromic acid are highly toxic/cancerogenic. Dont.More
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Evolution vs Creationism  Follow
SAFETYMore
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Edward W Hackett  Follow
It would no doubt be cheaper to buy a new test tube than the chemicals needed to dissolve the sulfur. More
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Geoff Richardson  Follow
I wouldnt heat toluene, xylene or carbon disulfide over a open flame. // Chromic acid is a common cleaning solution in a chem lab, but it is really nasty since it oxidizes "most" things. Not really something for a typical home lab in my mind.More
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Ali Zaker Apurbo  Follow

I once had this problem in the lab. I put some NaOH (I guess it can be found in some bleaches or cleaning supplies for declogging pipes) and water in it. It warms in the process, but it's not a problem. After an hour or so, and after bit of scratching (watch out, the brush might decompose in such basic solution), the sulfur was gone.

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Dr Balfaa  Follow
About the sodium hydroxide (NaOH) option: Ive had sulfur residue attached to my condenser. Letting the glassware bathe in high concentration NaOH, then washing it of with 10% hydrochloric acid (HCl) only partly removed the sulfur. It was unfortunately still detectable, by smell, when doing a simple water distillation.More
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Huang Lu  Follow
And I am not entirely sure the glass is immune from bathing in such concentrated sodium hydroxide, either.More
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Bruce Thomson  Follow

Hot sodium percarbonate solution can mildly oxidise some sulphur to SO2. It's safe and non toxic. Strong hot hydrogen peroxide will aslo oxidise some to H2SO4. And if its a test tube burning it off with a bunsen burner or buying a new test tube is probably the most cost effective choice. I have cleaned a sulphur dirty sinter using percarbonate then nitric acid.

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