Lecture 1Base UnitsPrefixesDerived Units -- 1Derived Units -- 2Derived Units -- 3non-SI Pressure UnitsInches of MecurySlide 9Temperature ScalesCelsius ScaleCelsius and FahrenheitKelvin and CelsiusMolesAvogadro’s Number (NA)HWLecture 1Lecture 1Dimensions and UnitsDimensions and UnitsBase UnitsBase UnitsLength: meter (m)Length: meter (m)Mass: kilogram (kg)Mass: kilogram (kg)Time: second (s)Time: second (s)Electric current: ampere (A)Electric current: ampere (A)Amount of substance: mole (mol)Amount of substance: mole (mol)Temperature: kelvin (K)Temperature: kelvin (K)http://physics.nist.gov/cuu/Units/current.htmlPrefixesPrefixeshttp://http://physics.nist.gov/cuu/Units/prefixes.htmlphysics.nist.gov/cuu/Units/prefixes.htmlDerived Units -- 1Derived Units -- 1Speed/velocitySpeed/velocitymsms-1-1AccelerationAccelerationmsms-2-2Force (Newton)Force (Newton)Use Newton’s 2Use Newton’s 2ndnd law: F = ma law: F = ma1 N = 1 kg1 N = 1 kgmsms-2-2Derived Units -- 2Derived Units -- 2Pressure (pascal) (Pa)Pressure (pascal) (Pa)Pressure = force per unit areaPressure = force per unit area1 Pa = 1 N1 Pa = 1 Nmm-2-2Exercise: Reduce to base unitsExercise: Reduce to base unitsDerived Units -- 3Derived Units -- 3Energy/Work (joule) (J)Energy/Work (joule) (J)Work = force x distanceWork = force x distance1 J = 1 N1 J = 1 NmmExercise: Reduce to base unitsExercise: Reduce to base unitsAnother approach – kinetic energyAnother approach – kinetic energyKE = ½ mvKE = ½ mv22Unit: kgUnit: kg(ms(ms-1-1))22(Another expression for 1 J)(Another expression for 1 J)non-SI Pressure Unitsnon-SI Pressure Units Millibar (mb)Millibar (mb)1 mb = 100 Pa = 1 hPa (hectopascal)1 mb = 100 Pa = 1 hPa (hectopascal) Atmosphere (atm)Atmosphere (atm)1 atm = 1013.25 mb 1 atm = 1013.25 mb Inches of mercury (in Hg)Inches of mercury (in Hg)Inches of MecuryInches of MecuryBased on operation of a mercury Based on operation of a mercury barometerbarometerPressure is proportional to height of Pressure is proportional to height of mercury columnmercury columnA “home-made” mercury barometerHeight of column = 29.92 inches for a pressure of 1 atmTemperature ScalesTemperature ScalesCelsius scale (Celsius scale (C)C)Fahrenheit (Fahrenheit (F)F)Kelvin (K)Kelvin (K)Celsius ScaleCelsius Scale00C = freezing point of pure water C = freezing point of pure water 100100C = boiling point of pure water at 1 C = boiling point of pure water at 1 atmatmCelsius and FahrenheitCelsius and Fahrenheit 32953259FCCFKelvin and CelsiusKelvin and CelsiusK = K = C + 273.15C + 273.15C = K – 273.15C = K – 273.150 K is called “0 K is called “absolute zeroabsolute zero””MolesMoles1 mole = an amount of atoms or 1 mole = an amount of atoms or molecules whose total mass equals the molecules whose total mass equals the molecular weight of the substance in molecular weight of the substance in gramsgramsExample: 1 mole of carbon 12 (C-12) is Example: 1 mole of carbon 12 (C-12) is the number of atoms in 12 g of C-12the number of atoms in 12 g of C-12Avogadro’s Number (NAvogadro’s Number (NAA))NNAA = number of atoms or molecules in 1 = number of atoms or molecules in 1 molemoleNNAA = 6.02 x 10 = 6.02 x 102323 mol mol-1-1Alternate definition of mole: amount of Alternate definition of mole: amount of substance containing 6.02 x 10substance containing 6.02 x 102323 moleculesmoleculesHWHWRead Stull, Appendix A. Read Stull, Appendix
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