Water Treatment and Purity

Lab Brief #5

🎯 Your mission

Set it up. Test it. Be amazed.

⚡ The twist

If it bubbles, something invisible is escaping.

What you'll learn

A pure substance in chemistry contains only one substance and melts at a single sharp temperature; a mixture melts over a range. Drinking water is not pure in that sense — it is filtered, sedimented and sterilised, but still contains dissolved salts.

Key words

pure substance
A single substance with a sharp, fixed melting and boiling point.
sterilisation
Killing microorganisms in water, usually with chlorine, ozone or ultraviolet light.

Make a hypothesis first

Guess: will the fizz be loud, soft, or none at all?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

plastic bottle
sand
gravel
cotton wool
muddy water
beakers

Get ready

⚠️ Safety first

Do not drink any water you filter, however clear it looks.
Wash hands thoroughly after handling soil, sand or pond water.

Step 1 of 4 · Read

Think about what you just learned: say what "pure substance" and "sterilisation" mean in your own words before you start.

Step 2 of 4 · Do

Build a filter column from sand, gravel and cotton wool and pass muddy water through it. Compare clarity before and after, then explain why the output is clearer but still not safe to drink.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 2

A pure substance melts at:

How sure are you?😐 maybe

Question 2 of 2

Filtering muddy water removes solids but not:

How sure are you?😐 maybe

Mind = blown

🧪 If you could remove all the empty space from atoms, the entire human race would fit in a sugar cube.

Nice work!

You got 0 of 2 right.

Next: Solubility Rules and Precipitation All lessons

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✨ More to explore

🌍 Where you see this in real life: Your toothpaste, your soap, even your breakfast involves this.

🏆 Stretch challenge (try it this week): Ask a grown-up to help you mix two safe kitchen things. Predict what will happen first.

👨‍👩‍👧 For the dinner table: “What's something we cook that mixes things together this way?”

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