Physical & Chemical Changes

Physical Change A change in which the Physical Properties of a substance is changed, but the substance is still the same substance. A change in size, shape, form, or state of matter that does not change the matter’s identity

Dissolving when one substance seems to disappear into a liquid or other solvent in a process which creates a solution This is a Physical Change

Change in State of Matter Melting, Boiling, Solidifying etc. A change in state does not change the particles that make up the substance Examples: Melting gold to form gold bars Water boiling and turning to water vapor

Chemical Change When one or more substances are changed into new substances Examples: iron rusting, baking a cake, sodium and chloride combining to form salt

5 Signs of a Chemical Change Formation of a gas that is not a change in state of matter (mixing baking soda and vinegar gives off a gas) Formation of a precipitate (solid forming when two liquids are mixed)

(signs of a chemical change continued) Color change Odor change Temperature change (two substances either give off heat or get cold when mixed)

Chemical Reactions The atoms in molecules of two or more substances combine and rearrange themselves to form new substances. Law of Conservation of Mass – the total mass before a chemical reaction is the same as the total mass after the chemical reaction