Matter and Its Changes Matter: anything that has mass and occupies space (has volume) anything that has inertia and requires a force to start or stop it from moving Observation: gathering information using one or more of our senses (sight, taste, touch, smell, and hearing) Two types: Qualitative: quality non-numerical information Ex. I am average height. Quantitative: quantity numerical information Ex. I am 175cm tall. Interpretation: an inference based on an observation Ex. Because Jim is wearing blue blue is Jim s favorite colour Inference Observation The Phases of Matter Solid, Liquid, and Gas also plasma but we don t worry about that in chemistry 11! it is like a gas, except it has charged particles found in nuclear explosions, on the sun, in neon signs http://video.google.com/videoplay?docid=673238280707 9775486 Temperature and Pressure affects which state matter is in 1
Properties of Solids: Properties of Liquids: Generally rigid Have their own shapes (definite shape) Volume changes only slightly due to temperature and pressure changes (definite volume) not compressible Take the shape of its container (indefinite shape) Volume changes slightly to temperature and pressure changes (definite volume) not compressible Properties of Gases: Molecules in the phases: Completely fill a container (indefinite shape) Volume changes drastically due to temperature and pressure changes (hence we don t heat compressed gases!) (indefinite volume) ARE compressible Gas Liquid Solid 2
Molecular Arrangement Kinetic Molecular Theory: arrangement of the molecules determines which state the matter is in Solids: highly organized, tightly packed particles Liquids: less organized particle arrangement, with particles still close together Gases: particles are far apart and moving around All particles are in motion! (they have energy) Either kinetic or potential energy Remember: energy is anything that is not matter and can cause a change in matter Energy can change forms, but it cannot be created or destroyed (Law of Conservation of Energy) therefore, the amount of energy is constant! Chemical Changes: Physical Changes: Chemical change: a change where a new substance is formed Indicators of a chemical change: Heat or light produced Colour change One or more of the reactants is used up Bubbles form (ie. gas is produced) Cloudiness (solid precipitate is formed) Physical change: a change in phase of a substance, but no new substance is produced Note: a physical change does not change the identity of the original chemicals Physical changes can also accompany chemical changes 3
Intensive Vs. Extensive Properties Can you figure out which is which? Intensive property: a physical property which depends on the nature of the substance NOT how much of the substance is present Extensive property: a physical property that depends on the amount of substance present Which are intensive and which are extensive? Melting point? Density? Mass? Volume? Boiling point? Answers: intensive, intensive, extensive, extensive, intensive Changes in State Terminology: Transitions between different phases of matter Ex. Liquid nitrogen evaporating to form gaseous nitrogen Note: The Law of Conservation of Mass still applies! There will still be the same amount of nitrogen as before (it is still nitrogen!) it is just in a different state Vapour: the material formed by the evaporation of a substance which boils above room temperature Ex. Acetone is a liquid that boils at 56 o C. The acetone that evaporates at room temperature (25 o C) is called a vapour Vapour Pressure: the pressure created by the vapour evaporating from a liquid 4
More Terminology: Boiling point: the temperature at which a liquid and gas substance are at equilibrium (they both exist) Melting point: the temperature at which a solid and liquid substance are at equilibrium Freezing point: the temperature at which a solid and liquid substance are at equilibrium (now changing from a liquid to a solid) Names for Phase Changes: Melting: solid to liquid Freezing: liquid to solid Boiling/Evaporating: liquid to gas Condensation: gas to liquid Sublimation: solid to gas or gas to solid Note: during a phase change the temperature does not change! Ex. While an ice cube is melting it will stay the same temperature until all the ice has turned to liquid Phase Diagram: What is on the exam? Boiling Temperature Melting Temperature 5