Matter and Change

Mixtures Mixture: A physical blend of two or more components. Salad Chicken noodle soup

Heterogeneous vs. Homogeneous Heterogeneous Mixtures  A mixture in which the composition is not uniform throughout. a) Chicken soup ingredients are not evenly distributed. Homogeneous Mixtures  A mixture in which the composition is uniform throughout.

Homogeneous Mixtures Solution: Another name for a homogeneous mix.  Many are liquids  Can be gas (air)  Can be a solid (stainless steel = iron + chromium = nickel) Phase: Term used to describe any part of a sample with uniform composition and properties.  Homogeneous mix. contains one single phase.

Homogeneous Mixtures Olive oil (Olive’s oil and different waxes) Vinegar (water and acidic acid) =

Homogeneous Mixtures Olive oil Vinegar (water and acidic acid)  When mixed together they form layers.  Both layers are phases.  The oil phase floats on the water phase. Both are mixtures

Separating Mixtures Differences in Physical properties can be used to separate mixtures. Separating Olive oil and Vinegar  Method one: pour off the oil. (oil floats on water)  Method two: freeze. Oil freezes before vinegar.

Separating Mixtures Filtration: separating a solid from a liquid. Distillation: boiling a liquid to produce a vapor then condensed into a liquid.

Section 2.4 Chemical Rxn. Physical Change: some properties of a material changes but the composition does not. Chemical Change: composition of matter always changes. Chemical property: The ability of a substance to undergo a specific chemical change. Ex. The ability to rust.

Chemical Properties. Are important because they can be used to identify a substance. Can be observed only when a substance undergoes a chemical change.

Physical Δ vs. Chemical Δ Physical Change: Iron and sulfide get separated with the use of a magnet. Chemical Change: Iron and oxygen form rust.

Chemical Reactions 1. When one or more substances change into one or more new substances. 2. A chemical change is also called a chemical Rxn. Reactant Product Substance present at the beginning Substance produced

Chemical Reactions Reactant Product Substance present at the beginning Substance produced

4 Clues to Chemical Changes 1. Transfer of Energy Every chem. Rxn involves energy. 2. A change in color. Cooked food browns illustrating a chem. Change. 3. The production of a gas. The bubbles from soap scum and cleaner. 4. Formation of a precipitate. Our demo on Tuesday.

Law of Conservation of Mass 1. In any physical change of chemical reaction mass is neither created or destroyed. 2. During a chemical reaction the mass of the products is always equal to the mass of the reactants.