[Samuelg]

Right i have a question, i've got no chemistry education and i am some what out of my depth.

Basically i am trying to detirmine the presence of sulphur dioxides in the smoke produced by burning a chemical which has a sulphur molecule in it.

My first question is, does the presence of a sulphur molecule in structure guarantee the release of sulphur dioxide when burnt/vaporised. I've put the skeletal structure below



Secondly i want to test for sulphur dioxide by bubbling the vapour through an acidified potassium dichromate solution and watch for the reduction if chromium from VI to III and thus turning green. However i'm having trouble finding the correct way of preparing the acidified solution. It has to be made with HCL correct ? but to what PH or does it just need to be below neutral ?

I know these are pretty simple questions for someone who is using chemicals like potassium dichromate which is pretty dangerous but i have experience in handling dangerous chemicals and all the necessary safety equipment, gloves, respirator, goggles etc.

Any help would be hugely appreciated.

[Arkcon]

I've moved this to analytical chemistry forum, since your purpose is the detection of something.  There may be commercially available cheaper or easier methods to analyze SO₂.  Often, you do get SO₂ from burning organic compounds that contain sulfur, if there's plenty of oxygen.  'Tho you may get other gasses at other times as well.  Generally, acidic dichromate is made with sulfuric acid.  It must be superior to HCl for some reason, maybe the volatility of HCl makes it less useful for industrial purposes.

[AWK]

It has to be made with HCL correct ?

Wrong! HCl also reacts with dichromate (slowly at RT).
Diluted H₂SO₄ with dichromate is always used.

[Samuelg]

Ah, well you saved me the task of finding and buying and then failing with HCL so thank you both for that not to mention the fact i was intending on using 96% pure HCL which is a somewhat risky venture. Sorry about posting it in the wrong section as you can probably tell I'm not a chemistry expert (far from it). With regards to the process of acidifying the K2Cr2O7 does anyone know if it must reach a certain PH before it functions correctly as an indicator ? I have searched around but can't seem to find anything regarding this part of the reaction.

[AWK]

using 96% pure HCL

Max. concentration of Hcl is 38%