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Physical & Chemical Properties

Physical & Chemical Properties. Scientists use characteristic properties to identify matter. Physical Properties. Many physical properties can be observed or measured Mass, volume, density (mass/volume) Color, shape, odor, texture Melting, boiling point Strength, hardness, Magnetism

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Physical & Chemical Properties

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  1. Physical & ChemicalProperties Scientists use characteristic properties to identify matter

  2. Physical Properties • Many physical properties can be observed or measured • Mass, volume, density (mass/volume) • Color, shape, odor, texture • Melting, boiling point • Strength, hardness, • Magnetism • Ability to conduct electricity or heat • State of matter (solid, liquid, gas)

  3. Specific Temperatures of Phase Changes SubstanceMelting Pt oCBoiling Pt oC Water 0 100 Gold 1063 2970 Carbon 3550 4827 Mercury -39 357 Nitrogen -209 -196 Oxygen -218 -183 NaCl 801 1413

  4. Density • All matter has mass, volume & density • Density determines whether an object will float or sink • Density is the amount of mass in a volume • Density = mass/volume • D=m/V

  5. Density Examples Chemical SubstanceFormulaDensity in g/cm3 • Air mixture 0.00129 • Helium He 0.00018 • Water H20 1.0 • Ice H20 0.92 • Steel mixture 7.8 • Iron Fe 7.86

  6. Physical properties help to determine uses • Copper used in electrical power lines • Antifreeze (ethylene glycol) remains a liquid at temperature that would freeze or oil water in a car radiator • Aluminum foil is lightweight, yet durable, water resistant and flexible

  7. Chemical Properties • Describes how a substance reacts • Reactivity – the ability of a substance to combine chemically with another substance (oxygen, acid, water or other substances) • Iron reacts with oxygen to make rust Fe2O3 • Flammability – the ability of a substance to react in the presence of oxygen and burn when exposed to a flame • Wood is flammable Gold is nonflammable

  8. Comparisons SubstancePhysicalChemical Helium less dense air nonflammable Wood grainy texture flammable Baking Soda white powder reacts w/vinegar Rubbing alcohol clear liquid flammable Iron malleable reacts with oxygen

  9. Physical Change • A change of matter from one form to another without a change in chemical properties • Torn paper • Melting ice • Crushing a can • Sanding wood • Dissolving sugar

  10. Although a physical change takes place, a substance will maintain its chemical properties • Melting, freezing and evaporation - all changes of state - are physical changes because the identity of the substance does not change • ice, water, steam – all are water! • Physical changes are often easily reversed.

  11. Mixtures can be separated using physical and chemical properties. • Physical properties such as solubility, magnetism, density and size can help separate mixtures.

  12. Chemical change • A change that occurs when a substance changes composition by forming one or more new substances. • Chemical changes are always accompanied by physical changes.

  13. Evidence of Chemical Reaction Chemical change or “reactivity” results in • Temperature change (always) • Flame or light or explosion • Change color • Bubbling (gasses) [NOT BOILING] • Oxidation (rusting or tarnishing) • Solid formation (precipitation) [NOT FREEZING]

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