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Milk goes through a cloth and stays white. Muddy water goes through and stays cloudy. Why?

Both liquids have pieces smaller than the holes in the cloth. So the pieces go through.

This is Chapter 5 of your Class 9 book, Exploration. It is called Exploring Mixtures and their Separation. Size of the pieces is the idea behind this chapter.

What you will learn

• Same all through, or not — homogeneous and heterogeneous mixtures.
• Three kinds of mixture — solution, colloid and suspension.
• Light through a mixture — the Tyndall effect.
• How strong a solution is — concentration as a percentage.
• Picking a method — match the method to a property, such as size.
• Getting back what dissolved — crystals, distillation and chromatography.
• More than two parts — the right steps, in the right order.

Need a quick recap?

You met these words in earlier classes.

• Solute, solvent, solution — what dissolves, what it dissolves in, and the mix.
• Saturated solution — it cannot dissolve any more solute.
• Filtering and evaporating — two simple ways to separate.
• A percentage — part over whole, times 100.

Start with one plain question. Is the mixture the same all through?