Presentation on theme: "DESCRIBE PHYSICAL & CHEMICAL CHANGES IN TERMS OF ENDOTHERMIC & EXOTHERMIC PROCESSES COS 5.0."— Presentation transcript:
1DESCRIBE PHYSICAL & CHEMICAL CHANGES IN TERMS OF ENDOTHERMIC & EXOTHERMIC PROCESSES COS 5.0
2WHAT YOU’LL LEARNExplain the relationship between, matter atoms & elementsCategorize materials as pure substances or mixturesIdentify elements & compoundsPerform calculations involving densityCompare & Contrast physical & chemical propertiesDetermine how the law of conservation of mass applies to chemical changesCompare & Contrast physical & chemical changesDescribe how to detect whether a chemical change has taken place.Describe the four common states of matter.List the different changes of state & describe how particles behave in each stateDescribe differences between endothermic & exothermic reactions
4COMPOSITION MATTER anything that has mass and takes up space (volume) ATOMSsmallest particle of an element that has same properties of elementMOLECULESsmallest unit of a substance that keeps all of physical and chemical properties of that substance.Two or more atoms that are chemically bonded
6PURE SUBSTANCEsample of matter, either a single element or a single compound, that has definite chemical and physical properties
7ELEMENTSsubstance that cannot be separated or broken down into simpler substances by chemical meansCan be found as solids, liquids, or gasesFound on periodic tableMade of identical atomsPure substancesRepresented by abbreviations/symbols consisting of one or two lettersExamples: H, N, S, O, P, Au, Hg, Na
8COMPOUNDSsubstance made of atoms of two or more different elements that are chemically combinedthey always combine in same proportions.Can be broken down through chemical meansPure substancesEvery compound is different from the elements it contains.
9CHEMICAL FORMULAScombo of chemical symbols and numbers to represent a substance.Subscriptrepresents number of atomslocated lower right of chemical symbolExamples: NO2, NH3, NaCl, C6H6O6
10MIXTURES two or more substances that are NOT chemically combined. Variable compositionEach components retains their characteristic propertiesMay be separated into pure substances by physical methodsclassified by how thoroughly the substances mix.Two types
11HOMOGENEOUS may be pure substances or solutions Pure substances may be compounds or elementssubstances are evenly distributed “well mixed”Look/have the same composition throughoutParticles are small and not easily recognizedcan be separated by physical means (dissolution, centrifuge, gravimetric filtering, etc.).Examples: milk, yogurt
12HETEROGENEOUS made of more than one kind of substance. substances aren’t mixed uniformly “least mixed”different particles in mixtures are large enough to be seeneasily separated by physical means (ie. density, polarity, metallic properties).
13Can it be separated by physical means? Matter FlowchartMATTERyesnoCan it be separated by physical means?MIXTUREPURE SUBSTANCEIs the composition uniform?noyesCan it be decomposed by chemical means?noyesHomogeneous Mixture(solution)Heterogeneous MixtureCompoundElement
21D M V Density V = 825 cm3 M = DV D = 13.6 g/cm3 1. An object has a volume of 825 cm3 and a density of 13.6 g/cm3. Find its mass.GIVEN:V = 825 cm3D = 13.6 g/cm3M = ?WORK:M = DVM = (13.6 g/cm3)(825cm3)M = 11,220 gDMV
22D M V Density D = 0.87 g/mL V = M V = ? M = 25 g V = 25 g 0.87 g/mL 2. A liquid has a density of 0.87 g/mL. What volume is occupied by 25 g of the liquid?GIVEN:D = 0.87 g/mLV = ?M = 25 gWORK:V = MDDMVV = g0.87 g/mLV = 28.7 mL
23D M V Density M = 620 g D = M V = 753 cm3 D = ? D = 620 g 753 cm3 3. You have a sample with a mass of 620 g & a volume of 753 cm3. Find density.GIVEN:M = 620 gV = 753 cm3D = ?WORK:D = MVDMVD = g753 cm3D = 0.82 g/cm3
25D M V Density M = 500 g D = M V = 25 cm3 D = ? D = 500 g 25 cm3 1. If the mass of a rock is 500 g and its volume is 25 cm3, what is its density?GIVEN:M = 500 gV = 25 cm3D = ?WORK:D = MVDMVD = g25 cm3D = 20 g/cm3
26D M V Density V = 10 ml M = DV D = 1.2 g/ml M = (1.2 g/ml)(10 ml) 2. If the density of a liquid is 1.2 g/ml and its volume is 10 ml, what is its mass?GIVEN:V = 10 mlD = 1.2 g/mlM = ?WORK:M = DVM = (1.2 g/ml)(10 ml)M = 12 gDMV
27D M V Density D = 1.6 kg/l V = M V = ? M = 80 kg V = 80 kg 1.6 kg/l 3. If Bob’s mass is 80 kg and his density is 1.6 kg/l, what is his volume?GIVEN:D = 1.6 kg/lV = ?M = 80 kgWORK:V = MDDMVV = kg1.6 kg/lV = 50 mL
28BOILING POINT temperature and pressure at which a liquid becomes a gas liquid is still the same substance
29MELTING POINTtemperature and pressure at which a solid becomes a liquid
30VISCOSITY resistance (difficulty) of a liquid to flow easily How “thick” or “thin” a liquid ishigh viscosity: Honey, motor oil, corn syruplow viscosity: water, milk, soda
31CONDUCTIVITY ability to conduct heat or an electric current High conductivity: metals (copper, aluminum…)Low conductivity: wood, rubber, plastic
32MALLEABILEAbility to be hammered into a thin sheet.
40SOLIDS Have a definite shape Have a definite volume Least amount of movement of particles.Particles arranged in a regular pattern and tightly packed.
41LIQUIDS Have an indefinite shape Have a definite volume will assume the shape of its container.Particles are close together but move about freely.
42GASES Have an indefinite shape Have an indefinite volume Can fill any container
43PLASMA most common form of matter. makes up over 99% of the visible universedangerous, very high energy (found in stars)
44ENDOTHERMIC/EXOTHERMIC REACTIONS Endothermic = heat energy is absorbed, cools surroundingsExothermic = heat energy is released, warms surroundings
45PHYSICAL CHANGESsubstance changes state but does not change its chemical composition.Type of matter remains the sameexample: water freezing into ice, cutting a piece of wood into smaller pieces
46DISSOLVING to disintegrate, break up, or disperse When a substance dissolves, the molecules of the substance do not change.Ways of Dissolving:solid in a liquid,gas in a liquidliquid in a liquid
47MELTINGto become altered from a solid to a liquid state usually by heatendothermicice cubes melting
48BOILING Change of a substance from a liquid to a gas. endothermic two types:Boiling:rapidgas bubbles are produced throughoutEvaporationslowoccurs at the surfaceis a cooling processocean water evaporates to form clouds & rain droplets
49CONDENSATION Change of a gas to a liquid. exothermic water vapor turns into dew
50SUBLIMATIONChanging directly from solid to gas or gas to solid skipping the liquid state.endothermicformation of frost/snow & dry ice
51FREEZING Changing from a liquid to a solid. Particles lose kinetic energy and slow down.exothermicwater turns to ice
52CHEMICAL CHANGESchange of a substance into a new and different substanceaka chemical reactioncannot be reversed by physical changes.impossible to “unbake” a cake.
53CHEMICAL REACTIONSReactants: are the substances that enter a chemical reactionProducts: are the substances formed by a chemical reaction
54CHARACTERISTICS & EXAMPLES OF CHEMICAL CHANGES Reaction with acids Digestion, fizzingReaction with oxygen (combustion) Explosions, BurningAbility to act as oxidizing agent RustingReaction with other elements production of heat, sound, lightDecomposition into simpler substances change of smell, DecomposingCorrosion water lines becoming thinChange in color -----Baking foodProduction of a gas Fermentation