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Mixtures Have Parts You Can Separate Back Out · Mixtures and Solutions · 5-PS1-4 · pure substances

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Mixtures Have Parts You Can Separate Back Out

with Atlas

Atlas stands at a wooden workbench covered in colorful bowls, holding a strainer over a sink while separating a muddy mix of sand, pebbles, and water back into separate piles, grinning as the clear water drips through.

Identify a mixture as a combination of two or more materials that each keep their own properties.
Compare a mixture to a pure substance by explaining what makes each one different.
Explain why the parts of a mixture can often be separated back out using physical methods.
Predict which separation method — sorting, filtering, or evaporation — would work best for a given mixture.
Demonstrate understanding by sorting example materials into 'mixture' or 'pure substance' categories.

Key terms

Mixture: Two or more materials mixed but not joined.
Pure substance: One kind of material all the way through.
Property: A trait, like chewy, crunchy, or shiny.
Separate: To take the parts of a mixture apart.

What Is a Mixture

A mixture is what you get when you combine two or more materials together. The best part is that each material keeps its own properties. In a bowl of trail mix, the raisins stay chewy, the peanuts stay crunchy, and the chocolate chips stay sweet. Nothing turned into something new just because they sit together. The parts are simply hanging out side by side, still acting exactly like themselves inside the bowl.

Pure Means Just One

A pure substance is made of only one kind of material all the way through. A glass of pure water is the same in every single drop, with nothing else mixed in. Because a mixture is made of separate parts that keep their own properties, you can usually pull those parts back out. You can pick out peanuts, filter sand from water, or evaporate water to leave salt behind. A pure substance has no parts to separate.

Worked examples

Is trail mix a mixture or pure?

Look at the parts: raisins, peanuts, and chocolate chips are all there.
Each part still keeps its own taste and feel, so they did not change.
Since it has two or more materials mixed together, it is a mixture.

Answer: Trail mix is a mixture, because it has many parts that stay themselves.

Hey there, scientist! I'm Atlas, and today we are going to dig into one of my favorite topics — mixtures! Imagine you pour a bag of trail mix into a bowl. You've got raisins, peanuts, and chocolate chips all in there together. That bowl is a MIXTURE. A mixture is when you combine two or more materials, but here is the cool part — each material KEEPS its own properties. The raisins are still chewy. The peanuts are still crunchy. Nothing changed about them just because they are together. Now think about a glass of pure water. That's just one kind of material all the way through. We call that a PURE SUBSTANCE. Every drop of pure water is exactly the same. Here's what makes mixtures extra special: because the parts keep their own properties, you can usually separate them back out! If you want your peanuts out of the trail mix, just pick them out — that's sorting. If you mix sand and water, you can pour it through a filter and the sand stays behind. If you dissolve salt into water and let the water evaporate, the salt is left behind. Remember: in a mixture, the parts are just hanging out together. They haven't turned into something new. That means you can always find a clever way to take them apart again!

Activity

Drag each item into the correct bin — is it a MIXTURE or a PURE SUBSTANCE?

Practice

Name one way to separate sand from a cup of water.

Is a glass of pure water a mixture or a pure substance?

Common mistakes to avoid

Mixing makes a brand-new material.In a mixture the parts keep their own properties and do not change.
Once mixed, parts can never be separated.Because the parts stay themselves, you can usually separate them again.

Check your understanding

You mix sand and iron filings together in a bowl. What is TRUE about this mixture?

Which of the following is the BEST example of a pure substance?

Mia dissolves sugar into warm water to make sugar water. Her friend says the sugar is gone forever. What should Mia tell her friend?

Recap

A mixture combines two or more materials that each keep their own properties, while a pure substance is just one material throughout. Because mixture parts stay themselves, you can usually separate them back out again.

Reflect

What mixtures can you find in your own kitchen?