Ch. 2 Notes Day 3

Objectives Review states of matter Review phase changes SWBAT identify different forms of physical change and chemical change SWBAT differentiate between physical and chemical change

Physical Change When you change the properties of a substance, but not the composition. Physical changes can ALWAYS be reversed!! Examples: Phase changes (changing the state of matter) Changing the shape or size of a substance Mixing or separating two substances together mechanically Homogeneous and heterogeneous mixtures

Filtration Separating particles based on their size (typically heterogeneous mixtures) Uses a material that has holes where small particles can pass through and larger ones cannot Examples: Coffee pot Soup ladle with holes Sieve for sand

Distillation Separates substances based on their boiling points (typically homogeneous mixtures) For example, the boiling point of water is much lower than salt. The fresh water turns to a gas, while the salt is left behind Examples Purifying salt water Distillation of whiskey

Chemical Property Any ability of a substance to change the composition of matter Chemical properties are observed when substances change Flammability – a substance’s ability to burn when oxygen is present Ex. Gasoline, very flammable. Milk, not flammable Reactivity – how easily a substance reacts with others Ex. Oxygen, highly reactive. Lead, not very reactive

Chemical Change When a substance reacts with others, and forms one or more NEW substances CANNOT BE REVERSED!! Evidence of chemical change Change in color Change in odor Production of gas

More evidence of chemical change Formation of a precipitate. Precipitate – a solid that forms when two solutions are mixed together Production of light. Light – the chemical reaction produces energy