MIXTURES

​MIXTURES

​Demonstrate and explain that mixtures of solids can be separated based on observable properties of their parts such as particle size, shape, color, and magnetic attraction.

​Mixtures are combinations of substances that are not chemically combined. Mixtures can occur in many states of matter-solids can mix with other solids or liquids, liquids can mix with other liquids or gases, and gases can mix with other gases. The components of mixtures can usually be separated by filtering or evaporation.

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Solutions, such as sugar dissolved into water, are mixtures that are homogeneous, or evenly mixed. Alloys are solid solutions. Other mixtures are heterogeneous because the composition of the mixture differs from place to place in the mixture.

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Mixtures also differ from compounds because their compositions can vary. Water is a simple compound. All water molecules have one oxygen and two hydrogen atoms. Granite is a mixture. Two samples of granite would each contain quartz, mica, and feldspar, but they may contain different amounts of each mineral.

Multiple Choice

​Mixtures are combinations of substances that are ______________.

• liquids

• different

• alike

• not chemically combined.

Multiple Choice

The components of mixtures ______ usually be separated by filtering or evaporation

• can

• can not

Multiple Choice

All water molecules have _____________.

• two oxygen and one hydrogen atoms

• one oxygen and two hydrogen atoms

• mixtures

• no atoms

​Mixtures can be separated by their physical properties, whereas compounds can only be separated chemically. Filtering can separate larger solid particles from liquids. Magnets can be used to separate iron and other materials that are attracted to magnets. Other physical properties, such as solubility, melting point, and density are also used to separate mixtures.

Multiple Choice

Mixtures can be separated by their _________________.

• chemical properties

• physical properties

Method: Magnetism

• Used to Separate: Iron, Nickel, Cobalt

• Example: Iron and Sand

• Example: Steel and Plastic

Method: Sieve or Strainer

• Used To Separate: Larger Particles from Smaller Particles

• Example: Rocks from Sand

Method: Filter

• Used to Separate: Small Particles

• Example: Water from Sand

Method: Density

• Used to Separate: Floating or Sinking

• Example: Salt and Pepper in Water

Method: Boil

• Used to Separate: Water (Evaporation)

• Example: Water and Salt

Separating Several Types of Matter

• Multiple Methods Can Be Used

• Example: Filter & Evaporation/Boiling

Separating Mixtures is a Physical Change

All Materials Still Have the Same Properties!

Multiple Choice

A magnet would be a good tool to use when you need to separate a mixture of iron filings and pepper.

• True

• False

Multiple Choice

A sieve would be a good tool to use to separate larger pieces from much smaller pieces in a mixture.

• True

• False

Multiple Choice

All materials will flow through a filter.

• True

• False

Multiple Choice

Mixtures can be separated when the materials in it have different densities.

• True

• False

Multiple Choice

To separate a solution (one substance dissolved into a liquid), the liquid can be boiled to separate the two substances.

• True

• False

Multiple Choice

Sometimes, more than one method of separating a mixture will be needed to separate all the materials in the mixture.

• True

• False

Multiple Choice

When mixtures are separated, it is a chemical change in matter.

• True

• False

​Matter can be changed physically or chemically. Physical changes do not change the chemical composition of a substance, but chemical changes do. Physical changes result in a change in at least one physical property of the substance, for example size, shape, or state. They do not change any of the chemical properties of a substance.

Water changing to ice is a physical change. Aluminum foil being crumpled and pressed into a small, hard lump is a physical change. Sugar dissolving into water is a physical change: the sugar is still sugar even though its molecules are suspended in water. Most physical changes can be reversed easily, such as evaporating the water from the sugar solution.

​PHYSICAL CHANGES

Multiple Choice

When you fold a piece of paper, which physical property changes?

• The color

• The texture

• The size

Multiple Choice

When we cut a piece of paper into triangles, which physical properties change?

• The smell and taste

• The texture and smell

• The size and shape

Multiple Choice

True or false: A physical change can result in an entirely different substance.

• True
• False

​CHEMICAL CHANGES

​On the other hand, chemical changes, such as rusting or burning, result in substances with new chemical and physical properties. Iron combines with oxygen to form rust. Carbon in paper or wood combines with oxygen to release heat and turn to ash. Chemical changes are not easily reversed.

Multiple Choice

Is glass breaking a chemical or physical change?

• chemical
• physical

Multiple Choice

Is a a rusting bicycle a chemical or physical change?

• chemcial
• physical

Multiple Choice

Is melting ice a chemical or physical change?

• chemical
• physical

Multiple Choice

Is spoiling food a physical or chemical change?

• phyiscal
• chemical