The States Of Matter All matter is made of something, even if it looks like nothing. We make...
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Transcript of The States Of Matter All matter is made of something, even if it looks like nothing. We make...
The States Of MatterThe States Of Matter
All matter is made of something, All matter is made of something, even if it looks like nothing.even if it looks like nothing.
We make classifications according We make classifications according to its properties, both chemical to its properties, both chemical
and physicaland physical
Three States of MatterThree States of Matter Solid: strong interactions Solid: strong interactions
Fixed shapeFixed shape Not compressibleNot compressible RigidRigid DenseDense
Liquid: medium interactionsLiquid: medium interactions
LiquidLiquid Not rigidNot rigid Assumes shape of containerAssumes shape of container Not compressibleNot compressible DenseDense
Gas: no interactionsGas: no interactions
Not rigidNot rigid Completely fills containerCompletely fills container CompressibleCompressible Low densityLow density
Plasma: the fourth statePlasma: the fourth state
At very high energies (temperatures) all the At very high energies (temperatures) all the electrons are removed from the atomselectrons are removed from the atoms
Not an important state for chemistryNot an important state for chemistry
Atom motion and temperatureAtom motion and temperature
Atoms in molecules have three types of Atoms in molecules have three types of motionmotion Rotation – moving about the centre of massRotation – moving about the centre of mass Vibration – vibrating about the centre of massVibration – vibrating about the centre of mass Translation – movement of the centre of massTranslation – movement of the centre of mass
As temperature increases, the energies of As temperature increases, the energies of all types of motion increaseall types of motion increase
SolidsSolids
Atoms in solids rotate and vibrate but do not Atoms in solids rotate and vibrate but do not translate translate
Melting occurs when the translational energy of Melting occurs when the translational energy of the atoms is sufficient to break free of the latticethe atoms is sufficient to break free of the lattice
Usually this is a very well defined pointUsually this is a very well defined point With amorphous solids it can be smeared out – With amorphous solids it can be smeared out –
softening of fatssoftening of fats
Vapour pressure and boilingVapour pressure and boiling
Molecules do not all have the same energyMolecules do not all have the same energy High energy molecules escape the liquid – vapour High energy molecules escape the liquid – vapour
pressurepressure When vapour pressure = atmospheric pressure When vapour pressure = atmospheric pressure
boiling occursboiling occurs Sublimation is direct transition of solid to gas (dry Sublimation is direct transition of solid to gas (dry
ice)ice)
Kinetic molecular theory and Kinetic molecular theory and pressure – a case for atomspressure – a case for atoms
Pumping up a tire increases the number of Pumping up a tire increases the number of moleculesmolecules
Pressure is caused by the energetic molecules Pressure is caused by the energetic molecules striking the tire wallstriking the tire wall
More molecules – higher pressureMore molecules – higher pressure Higher temperature – higher pressureHigher temperature – higher pressure
Under pressureUnder pressure
Gases exert pressure by virtue of motionGases exert pressure by virtue of motion Gravity makes the air density higher near Gravity makes the air density higher near
the earth’s surfacethe earth’s surface Pressure decreases with elevationPressure decreases with elevation
Atmospheric pressureAtmospheric pressure
The weight of the air supports a column of The weight of the air supports a column of mercury 760 mm highmercury 760 mm high
BarometerBarometer is used for measuring is used for measuring atmospheric pressureatmospheric pressure
Atmospheric pressure changes with the Atmospheric pressure changes with the weatherweather
The atmosphere is layeredThe atmosphere is layered
TroposphereTroposphere Where the weather happensWhere the weather happens
StratosphereStratosphere Where the ozone isWhere the ozone is MesosphereMesosphere IonosphereIonosphere
The brutal strength of solar radiation ionizes all the The brutal strength of solar radiation ionizes all the components – permits transmission of radio signals components – permits transmission of radio signals around the earth without need of mirrorsaround the earth without need of mirrors
Units of pressureUnits of pressure
mm (or cm) of mercury mm (or cm) of mercury Atmospheric pressure = 760 mm HgAtmospheric pressure = 760 mm Hg
Pascal is SI unit for pressurePascal is SI unit for pressure Atmospheric pressure = 101 000 kPaAtmospheric pressure = 101 000 kPa
Pounds/square inchPounds/square inch Atmospheric pressure = 14.7 lb/inAtmospheric pressure = 14.7 lb/in22
Standard temperature and pressure Standard temperature and pressure (STP)(STP)
Standard conditions allow direct comparison Standard conditions allow direct comparison of properties of different substancesof properties of different substances Standard temperature is 273 K (0Standard temperature is 273 K (0ºC)ºC) Standard pressure is 760 mm HgStandard pressure is 760 mm Hg
At STP, 1 mole of At STP, 1 mole of anyany ideal gas occupies ideal gas occupies 22.414 L22.414 L
Gas laws: experience in math formGas laws: experience in math form
The properties of gases can be described by a The properties of gases can be described by a number of simple lawsnumber of simple laws
The laws establish quantitative relationships The laws establish quantitative relationships between different variablesbetween different variables
They are largely intuitively obvious and familiarThey are largely intuitively obvious and familiar
The four variablesThe four variables
Pressure (P)Pressure (P) Volume (V)Volume (V) Temperature (T in Kelvin)Temperature (T in Kelvin) Number of molecules (n in moles)Number of molecules (n in moles)
Variables and constantsVariables and constants
In the elementary gas laws two of the four In the elementary gas laws two of the four variables are kept constantvariables are kept constant
Each law describes how one variable reacts Each law describes how one variable reacts to changes in another variableto changes in another variable
All the simple laws can be integrated into All the simple laws can be integrated into one combined gas lawone combined gas law
Boyle’s lawBoyle’s law
The first experimental gas The first experimental gas lawlaw
Pressure increases, volume Pressure increases, volume decreases (T, n constant)decreases (T, n constant)
1PV
Charles’ LawCharles’ Law
As temperature increases, As temperature increases, volume increases (P, n volume increases (P, n constant)constant) Temperature must be Temperature must be
measured in Kelvinmeasured in Kelvin
V T
Absolute zeroAbsolute zero
Gay-Lussac observed V changed by 1/273 Gay-Lussac observed V changed by 1/273 of value at 0of value at 0ºCºC
Plotted as V = Plotted as V = kkT (T = ºC + 273), V = 0 at T T (T = ºC + 273), V = 0 at T = 0= 0
Does the gas actually occupy zero volume?Does the gas actually occupy zero volume? No, at lower T the law is not followedNo, at lower T the law is not followed
Combined gas lawCombined gas law
Fold together Boyle and Charles:Fold together Boyle and Charles: PP11VV11/T/T11 = P = P22VV22/T/T22
Given five of the variables, find the sixthGiven five of the variables, find the sixth Units must be consistentUnits must be consistent Temperature in KelvinTemperature in Kelvin
Gay-Lussac and law of combining Gay-Lussac and law of combining volumesvolumes
When gases react at constant temperature When gases react at constant temperature and pressure, they combine in volumes that and pressure, they combine in volumes that are related to each other as ratios of small are related to each other as ratios of small whole numberswhole numbers
His experiments with hydrogen and oxygen His experiments with hydrogen and oxygen had implications for the understanding of the had implications for the understanding of the atom and the structures of simple moleculesatom and the structures of simple molecules
Avogadro’s LawAvogadro’s Law
As the number of moles of As the number of moles of gas increases, so does the gas increases, so does the volume (P, T constant)volume (P, T constant)
V n
Dalton’s law of partial pressuresDalton’s law of partial pressures
A mixture of gases exerts a pressure as if all A mixture of gases exerts a pressure as if all the gases were independent of one anotherthe gases were independent of one another
Total pressure is the sum of the pressures Total pressure is the sum of the pressures exerted by each oneexerted by each one
P = pP = p11 + p + p22 + p + p33 + … + …
Real world applications 1:Real world applications 1:Henry’s Law and sodie popHenry’s Law and sodie pop
The quantity of gas dissolved in a liquid The quantity of gas dissolved in a liquid depend directly on the pressure of that gas depend directly on the pressure of that gas above the liquidabove the liquid
Under pressure the COUnder pressure the CO22 in the liquid is kept in the liquid is kept in solutionin solution
Open the cap and the COOpen the cap and the CO22 rapidly escapes rapidly escapes
Real world applications 2:Real world applications 2:The science of breathingThe science of breathing
The gas laws explain the mechanics of The gas laws explain the mechanics of breathing: the transport of oxygen from the breathing: the transport of oxygen from the lungs and exchange with carbon dioxide lungs and exchange with carbon dioxide produced in the body.produced in the body.