matter : physical vs. chemical

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Matter : Physical vs. Chemical. Properties of Matter. Characteristics that enable us to distinguish one kind of matter from another. How can we distinguish hydrochloric acid from water?. Types of Properties. Extensive Depends on the amount of matter - PowerPoint PPT Presentation

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Unit I: Matter August 2005

Matter: Physical vs. Chemical

Properties of MatterCharacteristics that enable us to distinguish one kind of matter from another.

How can we distinguish hydrochloric acid from water?Types of PropertiesExtensive Depends on the amount of matter e.g., volume, mass, amount of energy (cal)Intensive Does not depend on the amount of matter e.g., melting point, boiling point, density, conductivityPhysical & Chemical PropertiesPhysical PropertyCan be observed or measured without changing a substances composition.4Demo- Sand What do you know about sand? Physical & Chemical PropertiesDemo: Ghost Crystals, Colorful Mixing Demo, Tarnished Silver, Magic SandPhysical PropertiesBoiling PointDensityMelting PointMalleabilityConductivityColorHardnessMagnetismAbility to transmit lightPhysical & Chemical PropertiesChemical PropertyCan only be observed by changing the composition of the materialChanges its identityChemical PropertiesThe ability of a substance toRustDecayBurnReact with acid, base, or waterFermentProperties of WaterWater expands as it freezes. (Physical)Hydrogen peroxide, H2O2 can decompose to produce water. (Chemical)Water boils quicker in Denver, CO than at the beach. (Physical)When an electrical current is passed through water, elemental hydrogen and oxygen are produced. (Chemical)Salt can dissolve in water. (Physical)

Physical & Chemical ChangesPhysical ChangeWill change the visible appearance, without changing the composition of the materialChanges that effect only physical properties.Does not change the composition!Physical ChangesBoilMeltFreezeDistillationSublimationExpandCrushDiffuseCondenseOsmosisCutSplitCrack

Physical changes are usually reversible10Demo: Chalk, Shredding paperPhysical & Chemical ChangesChemical ChangeChanges that involve a change in the composition of the substance.New matter is formed

Chemical Changes

FermentDecay/DecomposeReact with acid, base, or waterNeutralizeRustDigestTarnishExplode / BurnIgniteCookChemical Changesare usuallyNOT reversible12Rusting of a car2H2O 2H2 + O2Reactants the stuff you start with

Products- what you make

Arrow points from the reactants to the new productsThe products will have NEW PROPERTIES different from the reactants you started with

Indicators of Chemical ChangeColor ChangeGas produced Temperature changeLight producedPrecipitate formsIrreversibility Not easily reversed!Color ChangeVery hard to reverseThink about cooking an eggIndicators of Chemical Change

Gas producedBubbles are producedCareful there are examples of bubbles that are not chemical boiling water bubblesPhysical change Water vapor starts to form inside the liquid in the form of bubbles

Indicators of Chemical Change

Temperature changeHeat given off- ExothermicFeels hotFeel someone after they workout theyre hotHeat absorbed- EndothermicFeels coolSweating while working out

Indicators of Chemical Change

Light producedStriking a match flame producedFireworksIndicators of Chemical Change

Precipitate forms2 liquids solid + liquid

Indicators of Chemical ChangeLaw of Conservation of MatterIn any physical or chemical change, matter is neither created nor destroyed.During any chemical reaction, the mass of the products is always equal to the mass of the reactantsAll the mass can be accounted for!!Burning of wood results in products that appear to have less mass as ashes. Where is the rest??Law of Conservation of Matter

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