Sulphur practical 2016

You will be working in groups of three to produce the three allotropes of sulphur. Your submission must be in the form of a PDF file which you must upload to Moodle. 


Although you are allowed to work in groups, each person must be involved with making one of the allotropes, and each person in the group must submit their OWN prac report. If you are found to have copied from another student, even a member of your group, you will receive zero for the prac.

INSTRUCTIONS:

 GRADE 10 EXPERIMENT - SULPHUR 

AIM

To produce and determine the characteristics of the 3 allotropes of sulphur.

APPARATUS

You will need a Bunsen burner, some test tubes, beakers, an evaporating dish and protective goggles.

PART A - RHOMBIC SULPHUR

METHOD

  1. Add 2-3 spatula-fulls of flowers of sulphur to about 2 ml of carbon disulphide (CS2 ). Carbon disulfide is a solvent for phosphorus, sulfur, selenium, bromine, iodine, fats, resins, rubber, and asphalt. 
  2. Warm the mixture in a water bath until all the sulphur has dissolved. 
  3. Then pour the solution into a porcelain evaporating dish and place the latter on an outside window sill with the window open.
  4.  Wait until all the carbon disulphide has evaporated and describe the crystals that have formed. 
  5. While this is happening, place the evapourating dish on the palm of your hand.  What do you notice?

RESULTS

1)   Take a photo of the crystals on your tablet or cell phone. 
2)   Describe your observation about the properties of your rhombic sulphur.

PART B - MONOCLINIC SULPHUR

METHOD

  1. Make a saturated solution of sulphur in xylene in a test tube by warming (do not boil) the mixture gently over a flame
  2. Keep the mouth of the test tube well away from the flame until most of the sulphur has dissolved
  3. If all of the sulphur dissolves, put in some more as the solution must be saturated
  4. When most of the sulphur has dissolved place the test tube in a boiling water bath (obtain boiling water from the kettle and place above a lit bunsen burner). It is important that the water temperature remains above 95°C for at least 5 minutes in order for decent crystals to form
  5. Remove the test tube and describe the crystals that form.

RESULTS

1)   Take a photo of the crystals on your tablet or cell phone. 

2)   Describe your observation about the properties of your monoclinic sulphur.

PART C - PLASTIC SULPHUR

METHOD

Place 3 to 4 spatula-fulls of flowers of sulphur in a small test tube and gently heat over a Bunsen flame until the sulphur begins to boil (about 450°C). Pour the molten sulphur slowly into the cold water in an evaporating dish. After a minute or two, pour the water off and pick up the cooled sulphur with your hands. Describe the texture and colour.

RESULTS

1)   Take a photo of the crystals on your tablet or cell phone. 

2)   Describe your observation about the properties of your plastic sulphur.

INSTRUCTIONS

Answer the questions below and include the 3 photos in a PDF document.

CONCLUSION

1.      Sulphur exists in 3 allotropes. What are allotropes?

2.      Which allotrope is stable at room temperature?

3.      Describe the physical changes that sulphur undergoes upon being heated from room temperature to about 500°C.


Extra information:

How to create a PDF:

  1. Write your report in MS-Word, or similar program.
  2. When you are finished, click on "File". Select "Save As..."
  3. Write in a name for your file, and then change "Save as type" from .docx to .pdf
  4. Click save. You now have a PDF.