Physical and Chemical Changes Unit II—Part 2

Concept of Change Change: the act of altering a substance

Physical Change Physical change: a change that occurs that does not change the identity of the substance Melting ice (change in state or phase) What do the particles look like when ice melts? http://www.miamisci.org/af/sln/phases/index.html Freezing Kool-aid Tearing paper Boiling water (same as melting ice)

Chemical Changes Chemical change: a change that occurs causing the identity of the substance to change Burning Digesting food Reacting with other substances (give an example per reviewer) A chemical change is called a chemical reaction

Chemical Changes Cont’d How do you know a chemical change has taken place? http://www.pyroinnovations.com/videos.html Indicators of a chemical change: Evolution of light Evolution of heat Evolution of a gas Color change Formation of a precipitate - creation of a solid

Is it Physical or Chemical? Change Physical Chemical Melting cheese Burning wood Milk souring (Do all students relate to this?) Wadding up paper Bicycle rusting