Sulfur Lab
Safety:
Fire hazard. During this activity, the sulfur may catch fire and burn at the lip of the test tube.
Have wet towels readily available to smother the flame. Take care not to burn hands. Take care
not to overheat the sulfur. Sulfur dioxide is toxic. Dispose of sulfur in trash can. Refer to MSDS
sheet.
Part A: Rhombic Sulfur - Demonstration
1. Add a small scoop of sulfur to 3 mL of olive oil or mineral oil in a 50 mL beaker. Heat gently with
stirring for 10 - 12 seconds (do not go over about 80° C). Place a few drops of the warm solution
on a watch glass and set aside. Let crystals grow overnight or for several days.
Part B: Monoclinic Sulfur
1. Fill a test tube approximately 1/3 full with sulfur. Keep the sulfur powder off the sides of the
test tube.
2. Make a cone out of filter paper and place it in a funnel.
3. Heat the test tube of sulfur VERY slowly - passing it back and forth above the flame. Totally
melt to a liquid. (Use Bunsen burner and test tube clamp) (Keep the sulfur yellow)
4. Pour liquid sulfur into filter paper cone. As soon as a surface crust forms, open the filter paper
to original shape.
5. Make observations of crystals formed.
6. Clean up!!!!!
Part C: Amorphous Sulfur - Demonstration
1. Nearly fill a 250 mL beaker w/ ice water.
2. Fill test tube about 1/4 full w/ sulfur. (Keep sulfur off the sides of the test tube)
3. Heat sulfur slowly. It will pass through stages:
• melt to yellow liquid (individual rings of 8 sulfur atoms)
• red liquid (short chains of 8 sulfur atoms)
• dark reddish-brown thick syrup (longer chains of sulfur atoms that entangle)
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• dark runny liquid (longer chains of sulfur atoms that have enough energy to flow)
4. Pour hot sulfur into beaker of water. (quench)
5. Make observations of solidified sulfur.
6. Place in fume hood overnight. Make observations after 24 hours.
7. Clean up!!!!
Describe and sketch each allotrope of sulfur.
Notes:
The sulfur lab introduces:
• allotropes
• ways of forming crystals
• amorphous vs. crystalline structure
• solid state phase change
It is best to do parts A and C as demonstrations. Part B may be done by the students. Make sure
the room is adequately ventilated and check for known sulfur allergies ahead of time.
When pouring out the sulfur for Part C, leave some of the liquid sulfur in the test tube. It is
possible to observe a reversal of the structural changes that occurred during heating. The liquid
will become viscous and thick as it cools, and then runny again upon further cooling. When it gets to
this point, pour the remaining liquid into a beaker or cup of water. It should form small balls
instead of long strings. The balls are hard and when split open with a fingernail reveal small yellow
crystals on the inside.
Expected Results:
• Rhombic sulfur – small diamond shapes that will need magnification to view
• Monoclinic sulfur – long yellow spikes that do not need magnification to view but it is
worthwhile to use a stereoscope
• Amorphous sulfur – long, rubbery, amber-colored strands – their surface resembles the
scales on hair when viewed under a stereoscope
• Amorphous sulfur after 24+ hours – will begin to turn back to a yellowish color and will
become brittle – it is returning to a crystalline state – a solid state phase change is
occurring
Copyright © 2010, ASM International. All Rights Reserved.
Copyright © 2010, ASM International. All Rights Reserved.
Copyright © 2010, ASM International. All Rights Reserved.
These notes come from:
http://classes.uleth.ca/200501/chem28101/Expt10-Grp16.pdf
Other websites check out:
http://www.woodrow.org/teachers/chemistry/institutes/faraday/lab5.html
http://www.columbus.k12.oh.us/walnut_ridge/Sulfur%20(Expt%2024).html
http://dev.nsta.org/ssc/pdf/v4-0961s.pdf
Copyright © 2010, ASM International. All Rights Reserved.
Copyright © 2010, ASM International. All Rights Reserved.