Chemical Bond or Just Friends?
Compare compounds and mixtures using iron and sulfur.
What this lesson covers
Why it matters
Iron and sulphur in a bowl — a magnet plucks the iron straight out. Heat them and they fuse into iron sulphide, and the magnet grabs nothing. A mixture became a compound.
Predict first
What is the key difference between a compound and a mixture?
In a mixture the parts keep their properties and can be separated physically (magnet, filter). In a compound they're chemically bonded in a fixed ratio, with brand-new properties.
- A compound's elements are chemically bonded in a fixed ratio — correct
- A compound is always heavier than a mixture
- They are the same thing
What you do
Sort each: a chemically bonded compound, or a physical mixture?
Check yourself
You can pull the parts out with a magnet or by filtering. It must be a…
Physical separation (magnet, filter, evaporation) works on mixtures, not compounds.
Which has its elements chemically bonded in a fixed ratio?
Only compounds lock their elements in a fixed, bonded ratio; air and salt water are mixtures.
- Mixture — correct
- Compound
- Element
- A compound like water — correct
- Air
- Salt water