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Pure Substances�and Mixtures

Grade 7 Science

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Pure Substances and Mixtures

Lesson 2

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Pure Substances and Mixtures

  • All matter that we come into contact with in the world is either a pure substance or a mixture.

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A pure substance is a type of matter that is made up of only one type of particle.

Pure Substance

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A mixture is a type of matter that contains more than one kind of particle. It has at least two pure substances mixed together.

Mixture

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Pure Substances and Mixtures

  • All matter that we come into contact with in the world is either a pure substance or a mixture.

Pure Substance

Mixture

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Pure Substances and Mixtures

  • All matter that we come into contact with in the world is either a pure substance or a mixture.

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Table Sugar

Table sugar contains only sugar particles.

Pure Substance

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Apple Juice

Apple juice is a mixture of sugar, water, vitamins, etc.

Mixture

  • Pure substances and mixtures can be in solid, liquid, or gas form.

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Mixture or Pure Substance?

  • Milk is a mixture.
  • It contains water, sugar, calcium, etc.
  • Milk is a mixture in liquid state.

MILK

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Mixture or Pure Substance?

  • Salt is a pure substance.
  • It only contains salt particles.
  • Salt is a solid.

SALT

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Mixture or Pure Substance?

  • Sea water is a mixture.
  • It contains water salt, bacteria, etc.
  • Sea water is a liquid.

SEA�WATER

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Mixtures

  • There are two types of mixtures: mechanical mixtures and solutions.

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A mixture in which you can see the different parts. They are also called heterogeneous mixtures.

Mechanical Mixture

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A mixture in which you cannot see the different parts. They are also called homogeneous mixtures.

Solution

Mixtures

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Mechanical Mixture or Solution?

  • Pizza is a mechanical mixture – you can see different parts of the mixture.
  • The parts of the mixture are solids.

PIZZA

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Mechanical Mixture or Solution?

  • Hand sanitizer is a solution – you can’t see all the different parts.
  • Hand sanitizer is a liquid solution.

HAND

SANITIZER

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Mechanical Mixture or Solution?

  • Steel is a solution – you can’t see the different parts of the mixture.
  • Steel is a solid solution.

STEEL

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Mechanical Mixture or Solution?

  • Cereal is a mechanical mixture – you can see different parts of the mixture.
  • It is a mixture of solids and liquids.

CEREAL�AND MILK