Changes in Matter Physical Change Can be reversed No new material created Phase change

Chemical Change Cannot be reversed New substance made One or more of the following occur: * color change * temperature change (hotter or colder) * flashes of light or sound * gas produced ~ bubbles * new odor

Signs of Chemical Reactions There are five main signs that indicate a chemical reaction has taken place: release input change in color change in odor production of new gases or vapor input or release of energy difficult to reverse

Physical or Chemical Change

Frying an Egg

Chemical Color change Odor change Cant turn it back into raw egg

Boiling Water

Physical Change in state of matter only Can turn steam back into liquid Molecules are still H2O

Burning gasoline www.wusa9.com/news

Chemical New material made Odor change Cant turn back to gasoline

Sour Milk

Chemical Odor change Taste change New chunky substance made Cant turn back to milk

Compression of a spring

Physical Still a spring Returns to normal shape after it is released

Rusting bicycle timberspringsphotography.com

Chemical Color change Texture change Cant turn back to metal New material

Gases No definite shape Lots of energy Volume can change Often created in a chemical reaction

Oxygen O Colorless Odorless Tasteless Flammable Fuels a fire

Hydrogen H Colorless Odorless Tasteless Explosive in fire Makes a “popping” noise In fire

Carbon Dioxide CO2 Colorless Odorless Tasteless Dense Puts out a fire

Test for Type of Gas Glowing wood splint