PHASE CHANGES Unit I - 2 Hebden 59-61

Chemical and Physical Characteristics of Compounds Property is a characteristic of a material that can be determined by observation or measurement. Allows one material to be distinguished from another

Physical Properties Characteristic of a substance that do not involve chemical change Physical Change Does not form a new substance Only the state, shape or external appearance of matter is changed

Physical Change Phase Change

PHASE CHANGE

solid Melting/freezing liquid gas Boiling or condensing

PHASE CHANGE Phase changes occur on the level portion of the graph only Heat is used for a phase change so the temperature doesn’t increase

Physical change Atoms are not rearranged to make new substances Examples cutting paper, shaping wood etc

Physical Properties Include: Malleability (ability to be hammered without breaking) Ductility (ability to be stretched into wires) Magnetism Conductivity State (solid, liquid, gas)

Chemical Properties Are ways in which a substance reacts with other substances or undergoes a chemical change Include: The ability to burn The ability to react with water Reaction with blue and red litmus paper

Chemical Change One or more new substances are formed in a chemical reaction New substances formed by a chemical reaction or chemical change have properties different from those of the starting materials

Chemical Reactions In chemical reactions The starting materials are called reactants The resulting materials are called products

Signs --- that a chemical change has occurred Bubbles of gas appear Precipitate forms Change in colour Temperature change Light is emitted A change in volume A change in conductivity A change in melting or boiling point

Chemical Change