Trying to get the parts back
Show on a big screenIron filings (tiny bits of iron) and sulfur powder are mixed. Then the mix is heated. Can you still get the iron back?
A physical method, such as using a magnet, makes no new substance.
- Start: try physical separating on the sample.
- Parts come out: it was a mixture.
- No physical way works: try a chemical change next.
- Simpler parts come out: a compound. None ever come out: an element.
No. Heating joins the iron and sulfur into a new compound.
Before heating, the powder is a mixture. After heating, it is iron sulfide, a compound. A magnet pulls iron out of the mixed powder. It does not pull iron out of the heated powder.
The rule
Physical methods can separate a mixture. They cannot separate a compound into its elements. Iron mixed with sulfur is still pulled by a magnet. A compound has new properties.
That is because joined elements make a new substance.
A teacher does the heating in class. Never heat chemicals at home.
Pick a sample and a test. See what happens.
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Try the lab to finish this lesson.