Physical properties are characteristics of a substance that can be observed without changing the composition of the substance. Physical properties are often used to separate a mixture into its original components. Imagine that you have been given a mixture of sand, sugar, and iron filings. You know that iron is attracted to a magnet, sugar dissolves in water and sand does not, and sugar has a higher boiling point than water. Each of these properties is a physical property. Think about how you can use these facts about the physical properties of the sand, sugar, and iron filings in order to separate them out of the mixture.

1. What do you separate in the first step? How?2. What is separated out in the second step? How?3. What happens in the third step?

Bellringer/Section 3 Notes: 1-18-11

I. Physical Changes

A. Physical Change – Affects one or more physical properties of a substance without changing its identity

Is water changing from a liquid to a gas an example of a physical change?

1. Dissolving solids into liquids is a physical change

B. Mixtures can be physically separated

1. Mixtures can be easily separated based on the properties of the substances that make up the mixture

2. Mixtures can be separated different ways:

a. Centrifuge

b. Distillation

c. Other methods such as using a magnet or boiling

Centrifuge – a device that physically separates mixtures.

II. Chemical Changes

A. Chemical Change – One or more substances are changed into new substances that have different properties

1. Indicators of a chemical change:

a. Smellb. Fizzingc. Foamingd. Color change

2. Chemical changes cannot be undone through a physical change