Could you remove the iron from iron sulfide using a magnet? Explain your answer.
Answers
Answer:
the iron and sulfur still behave like iron and sulfur in the mixture, but iron sulfide has different properties from both iron and sulfur. you can separate the iron from the mixture using a magnet, but this does not work for iron sulfide.
Answer:
Elemental iron and sulfur are converted to iron(II)sulfide. The resulting compound lacks the magnetic properties of unreacted iron.
Equipment
10x75 mm test tubes (3)
weighing dish for mixing the solids
medium sized magnet (stir bar)
propane torch or Bunsen burner
ringstand
test tube clamp
wad of glass wool to plug test tube
corks to fit test tubes (3)
thread
Reagents
powdered iron
powdered sulfur
Presentation
Thoroughly mix 2 grams of sulfur with 3.5 grams of iron until the mixture is uniform.
Fill a test tube approximately 25% full with the mixture.
Fill another test tube with about the same amount of pure sulfur as there is sulfur in the first test tube.
Fill another test tube with about the same amount of pure iron as there is iron in the first test tube.
Cut 3 pieces of thread about 35 cm long. Tie a knot in the end of each thread. Place the knot of a thread into each of the test tubes and press the corks firmly in place.
Take the test tube filled with sulfur and hold it by the end of the thread, so that the test tube hangs freely in space. Bring the end of the magnet to the test tube and slowly move it horizontally away from the test tube. Note that the test tube does not follow the magnet.
Repeat step 6 for test tubes containing the iron and the iron/sulfur mixture. Note that these test tubes do follow the magnet.
Remove the cork from the test tube with the mixture, plug the end of the tube with the glass wool, clamp the test tube in the ringstand at a 45º angle.
Light the torch or burner and adjust the flame until you have a small well defined inner blue cone. Play the flame over the bottom of the test tube, heating gently. Very soon the sulfur will melt and the reaction will be initiated. Remove the flame and note how the red glow travels up through the mixture as the reaction proceeds. There will be a brief puff of sulfur/sulfur dioxide from the end of the test tube.
After the reaction has ceased, play the flame along the length of the test tube containing the products until the test tube glows red. The extra heating ensures that the reaction goes further towards completion.
When the test tube is cool enough to handle, remove the glass wool and replace the thread and cork.
Repeat step 6 for the test tube containing the product, FeS. Note that the test tube has little or no attraction to the magnet.
Details
The elements iron and sulfur will be converted into the compound iron(II) sulfide by heating the reactants in a test tube until the reaction is initiated and then the exothermic nature of the reaction will continue until the reaction is complete.
Fe (s) + S (s) → FeS (s) + heat
The proof that a reaction has taken place can be demonstrated by examining the magnetic properties of the contents of the test tube before and after the reaction. Before the reaction the test tube will be strongly attracted to a magnetic field due to the ferromagnetism of the elemental iron. After the reaction, assuming you completely use up the iron, the only magnetic attraction can come from the paramagnetic attraction of the iron(II) as part of the compound. Iron(II) is a d6 ion, which, depending upon the spin state (high spin or low spin), will have five or one unpaired electrons. Regardless of the spin state, paramagnetism is a much weaker force than ferromagnetism and so there will be a much smaller attraction of the test tube to a magnetic field.
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