Chemical Reactions

4.1  Introduction for Reactions

Essential Knowledge:

*These are taken directly from College Board

• A physical change occurs when a substance undergoes a change in properties but not a change in composition. Changes in the phase of a substance (solid, liquid, gas) or formation/separation of mixtures of substances are common physical changes. (TRA-1.A.1)   

• A chemical change occurs when substances are transformed into new substances, typically with different compositions. Production of heat or light, formation of a gas, formation of a precipitate, and/or color change provide possible evidence that a chemical change has occurred. (TRA-1.A.2)