(colloid) Fog scatters light… that is why it is dangerous to drive in the fog. Liquid particles are dispersed in a gas. NO HIGH BEAMS in the FOG!
Specific Heat The heat required to raise the temperature of the unit mass of a given substance by a given amount (usually one degree)
Thermite Reaction Iron (III) oxide = molten iron.
Unit 1 matter and physical chemical changes NOTES
Matter: anything that has mass andtakes up space Mass – the amount of matter in something. Volume – the amount of space somethingoccupies.Weight = amount of matter + Effect of GravityReviewing MATTER
Matter, Mass, and Weight Do you think you would weigh thesame if you stood on the surface ofthe planet, Mercury? Mercury is the smallest planet, andthe planet closest to the sun. Thegravity of Mercury is 38% of Earthsgravity. To calculate your weight onMercury, multiply your weight by 0.38.
A. Matter FlowchartMATTERCan it be physicallyseparated?HomogeneousMixture(solution)HeterogeneousMixture Compound ElementMIXTURE PURE SUBSTANCEyes noCan it be chemicallydecomposed?noyesIs the compositionuniform?noyesColloids Suspensions
B. Pure Substances Element composed of identical atoms EX: copper wire, aluminum foil
B. Pure Substances Compound composed of 2 or moreelements in a fixed ratio properties differ from thoseof individual elements EX: table salt (NaCl)
B. Pure Substances For example…Two different compounds,each has a definite composition.Law of definite proportions: Regardless of the amount, acompound is always composed of the same elements in theproportions by mass.
C. Mixtures Variable combination of 2 or more puresubstances.Heterogeneous Homogeneous
C. Mixtures (Homogeneous) Solution (homogeneous) Dissolving homogeneous very small particles No Tyndall effectTyndall Effect particles don’t settle EX: rubbing alcohol
C. Mixtures Suspension heterogeneous large particles particles settle EX: sand and water
C. Mixtures Examples: Whipped Cream muddy water fog saltwater Italian saladdressingcolloidsuspensioncolloidsolutionsuspension
What is a property? Property: acharacteristic ofa substance thatcan be observed
Physical PropertyExamples:• luster• malleability: the abilityto be hammered into athin sheet• ductility: the ability tobe stretched into a wire• melting point• boiling point• density• solubility• specific heat•Mass•Volume•Length•color
Special Physical Properties Melting point: the temperatureat which a substance changesfrom a solid to a liquid at a givenpressure.water = 0oC Boiling point: the temperatureat which a substance changesfrom a liquid to a gas at a givenpressure.water = 100oC
Chemical Properties Chemical property: a propertythat can only be observed bychanging the identity of thesubstance.Examples:•flammability•ability to rust•reactivity with vinegar•The ability to NOT react
Physical Vs. ChemicalProperties1) The melting point of water is 00C.2) Ethanol burns in the presence of oxygen.3) Potassium explodes when placed in water.4) Oil has a very high viscosity.5) Gold does not react when placed in water.6) Nonmetals are very brittle.7) The density of aluminum is 2.70 g/mL8) Iron rusts in our atmosphere.
Physical and Chemical ChangesChange: the act of alteringa substance
Physical Change Physical change: a change thatoccurs that does not change theidentity of the substance Form Size State or phase Dissolving
Physical Change Examples: Melting ice (change in state or phase) Freezing Kool-aid (change in state or phase) Tearing paper (change in form or size) Boiling water (change in state or phase)
Chemical Changes Chemical change: a change thatoccurs causing the identity of thesubstance to change Burning Digesting food Reacting with other substances A chemical change is called achemical reaction.
Chemical Changes Cont’d Indicators of a chemical change:Development of lightDevelopment of heatDevelopment of a gasColor changeFormation of a precipitate
Is it Physical or Chemical?Change Physical ChemicalMelting cheeseBurning woodMilk souringWadding up paperBicycle rusting