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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. Chicken soup ingredients are not evenly distributed.
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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. • 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 Both are 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.
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 Substance present at the beginning Substance produced When one or more substances change into one or more new substances. A chemical change is also called a chemical Rxn. Reactant Product
Chemical Reactions Substance present at the beginning Substance produced Reactant Product
4 Clues to Chemical Changes • Transfer of Energy • Every chem. Rxn involves energy. • A change in color. • Cooked food browns illustrating a chem. Change. • The production of a gas. • The bubbles from soap scum and cleaner. • Formation of a precipitate. • Our demo on Tuesday.
Law of Conservation of Mass In any physical change of chemical reaction mass is neither created or destroyed. During a chemical reaction the mass of the products is always equal to the mass of the reactants.