Elements, Compounds and Mixtures
5 marks · EasyA student finds a mixture of iron filings and sulfur powder. She wants to investigate how to classify and separate these substances.
State whether iron, sulfur, iron sulfide, and a mixture of iron and sulfur are elements, compounds or mixtures.
Describe a physical method you could use to separate the iron filings from the sulfur powder in the mixture.
Explain why you cannot separate iron sulfide into iron and sulfur by a physical method.
Work this out on paper, then compare with the answer and worked solution below. With a free account you can submit written answers for marking.
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(a) — · must show Iron: element, Sulfur: element, Iron sulfide: compound, Mixture of iron and sulfur: mixture
(b) Use a magnet to attract the iron filings away from the sulfur powder. · must show magnet, magnetic separation
(c) Iron sulfide is a compound, so iron and sulfur are chemically bonded together. Physical methods cannot break chemical bonds; a chemical reaction is needed. · must show elements are chemically combined in a compound, physical methods cannot break chemical bonds
Show mark scheme and worked solution
Marking points
B1 (a) · 1 mark · Iron and sulfur correctly classified as elements.
B2 (a) · 1 mark · Iron sulfide as compound and mixture of iron and sulfur as mixture.
M1 (b) · 1 mark · Correctly describes magnetic separation.
M2 (c) · 1 mark · States iron and sulfur are chemically combined in iron sulfide (compound).
E1 (c) · 1 mark · Explains that physical methods cannot break chemical bonds and a chemical reaction is needed.
Worked solution
a) Iron and sulfur are elements. Iron sulfide is a compound. A mixture of iron and sulfur is a mixture.
b) Use a magnet to separate the iron filings from the sulfur, as iron is magnetic and sulfur is not.
c) In iron sulfide, iron and sulfur are chemically joined to form a compound. Physical methods such as using a magnet cannot break the chemical bonds; separating iron and sulfur requires a chemical reaction.