CHEMICAL & PHYSICAL CHANGES REVIEW

a quick review of:

​CHEMICAL & PHYSICAL CHANGE

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CHEMICAL & PHYSICAL CHANGE

THE STATES OF MATTER

The particles in a solid are close together and vibrate.

The particles in a liquid are further apart and slide over each other.

The particles in a gas are far apart and bump into each other as they move quickly

Matter is anything that has mass and is in one of the states of matter.

Matter exists in three main forms: solids, liquids, and gasses.

When substances are combined or energy is added or released from a system, those substances may undergo changes.

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CHEMICAL & PHYSICAL CHANGE

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May change the observable properties of a substance, but they do not produce any new substances.

A mixture is a substance in which two or more substances are combined without a chemical reaction between them.

CHEMICAL CHANGES

​Chemical changes create something NEW!

​When a chemical change occurs, the substance is destroyed forever: you cannot put it back in its original form. The chemical compositions are different from than the original substances.

Evidence of a chemical change may include: a color change, the production of gas (bubbles or odor), the formation of a cause (a solid that falls to the bottom of a liquid) or a change in energy (observed as a change in temperature)

physicaL CHANGES

A physical change is any change in the way something LOOKS (shape, color, size)

For example, phase changes in water involve changes in the motions of the particles of water with changes in temperature, but they do not change the composition of the substance. 

mixtures

The substances retain their original properties and can be separated from the mixture if need be.

For example - a bowl of cereals mix, cookie dough, salt mixed in water, carbon dioxide in coke, a tossed salad etc. Air is the most common mixture around us. 

Multiple Choice

If sugar and sand are mixed, which of the following methods would separate the sugar and sand?

• they cannot be separated

• melt the mixture in a pot

• pour the mixture through a sieve

• pour the mixture into water to dissolve the sugar

Multiple Select

Which of these are physical changes? Select TWO answers

• twig burns

• a ruler breaks

• a sugar cube dissolves

• nail rusts

• a spoon tarnishes

Multiple Select

Which are examples of chemical changes? Select TWO answers

•  leaves in a compost pile rot

• sugar dissolves in water

• an egg is cooked

• water in a pan boils away

•  a silver quarter tarnishes

Multiple Select

Materials can be changed in many ways. Which of the following describes only physical changes? Select 2 correct response

• eating the marshmallow

• Bending the wiring roasting stick

• striking a match and lighting a fire

• burning a marshmallow and placing it on a piece of chocolate

• tearing open a graham cracker package and breaking a cracker in half