Pure or Impure?
Sort matter into pure substances and mixtures.
What this lesson covers
Why it matters
A nugget of gold is gold all through. A cup of nimbu paani is sugar, salt, lemon and water mingling. One is a single substance; one is a jumble.
Predict first
What is the difference between a compound and a mixture?
An element is one kind of atom; a compound is elements chemically bonded in a fixed ratio; a mixture is substances jumbled in any ratio, keeping their own properties.
- A compound's elements are chemically joined in a fixed ratio; a mixture is just jumbled — correct
- A compound is always a solid
- There is no real difference
What you do
Sort each sample: a single element, a compound, or a mixture?
Check yourself
Which one is a compound?
Water is two elements chemically bonded in a fixed 2:1 ratio — a compound. Air is a mixture; copper is an element.
What makes a mixture different from a compound?
Mixtures have no fixed ratio and the parts keep their own properties, so they can be separated physically.
- Water (H₂O) — correct
- Air
- Copper
- Its parts keep their properties and can be in any ratio — correct
- It always has a fixed formula
- It is always a liquid