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Unit 2 Continued. Matter/Physical vs. Chemical Changes/ Law of Conservation of Mass. Matter. Matter is anything that takes up space and has volume. 3 phases of matter: Solid Liquid Gas. Solids. Shape: tightly packed particles; very ordered Volume: definite volume
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Unit 2 Continued Matter/Physical vs. Chemical Changes/ Law of Conservation of Mass
Matter • Matter is anything that takes up space and has volume. • 3 phases of matter: • Solid • Liquid • Gas
Solids Shape: tightly packed particles; very ordered Volume: definite volume Compressibility: incompressible Examples: coal; sugar; ice
Liquids Shape: less tightly packed, less order, take container’s shape. Volume: indefinite volume Compressibility: low compressibility Examples: water
Gases Shape: particles far apart, no order Volume: indefinite volume Compressibility: very compressible Examples: air, oxygen, CO2
Entropy • Entropy is a measure of disorder. • The more order the particles have, the less entropic they are.
Entropy Highest Entropy Lowest Entropy Least Ordered Most Ordered
Physical Changes • Chemical composition remains the same. • Physical appearance or state of matter may change; but actual properties do not change. • Usually a reversiblechange.
Examples of Physical Change: • Boil • Freeze • Crush • Dissolve • Melt • Bend • Condense • Split • Crack • Grind • Cut
Chemical Changes • When a substance changes into a totally new substance. • The actual chemical composition is changed. • Cannot be easily reversed
Indications of a Chemical Change: • Change in color or odor • Production of a gas (bubbles) • Energy released or absorbed (heat of light) • Formation of a precipitate (solid)
Examples of Chemical Change: • Burn • Rot • Rust • Corrode • Explode • Decompose • Ferment
Law of Conservation of Mass • Matter cannot be created or destroyed • The reactants and products must have equal masses.
Law of Conservation of Mass • Reactants: The starting substances in a chemical reaction. • Products:Substances formed in a chemical reaction.
Law of Conservation of Mass (Reactants) (Products) Iron + Sulfur Iron Sulfide 5g + 5g = 10g If you react 5g of iron with 5g of sulfur, 10g of iron sulfide will be produced.