No Slide Title

Protons for Breakfast

Heat

Week 3

March 2013

In the event of

In the event of an attack of giant hens

Electromagnetic waves

ElectricityHeat

How it all fits togetherAtomsAnd a pictorial summary for those who appreciate things that way.Tonights talkAtoms and molecules are ceaselessly moving

Temperature is a measure of how fast the atoms and molecules are moving

Atoms and molecules are constantly emitting and absorbing electromagnetic waves

The frequency of the waves emitted and absorbed depends on temperature

Here we see tonights summary.

Focus particularly up on the second pointKey fact to remember

There are VAST numbers of atoms in everything.In just a handful of anything there are about the same number of atoms as there are grains of sand on all the beaches and deserts on Earth combinedPhoto Credit: http://www.morguefile.com ID = 104101It you dropped a cup of water in the ocean and waited for it to mix with the whole ocean (a long time) then if you dipped your cup anywhere in the ocean, you would be likely to capture some of the atoms you originally poured in.

Really?: From the Web I see the average depth of the oceans is 3500 m and they cover around 70% of the Earth's surface. Their volume is therefore amounts to 1.3 x1018 cubic metres which is 1.3 x 1021 litres. If a cup contains 300 ml, then when poured into the ocean it will be diluted 1 part cup-water to 4.2 x 1021 parts ocean water. Now 18 ml of water contains 6 x 1023 molecules so 300 ml contains 1025 molecules. After dilution, each cup-size part of ocean water will contain 2380 molecules of water. Ish

6400000 m = radius of Earth in metres (m)1.2868E+14 = Surface area of Earth0.3 = Fractional Surface area of Land1m Depth Layer3.86E+13 = Volume (m3)of surface layer 1 m deep1 mm^3 = Volume of a single grain (mm^3)0.000000001 = Volume of a single grain (m^3)3.86E+22 = Number of particles in layer

Typica ldensity of anything = 5000kg/m^3Typical Molecular Weight 50Typical molar volume 0.00001 m^3Typical molar volume 0.01 litresTypical molar volume 10 ccSo 1 cc is about 0.1 mole1cc is about 6.2e22 particlesLet us embark on a temperature excursionRoom TemperatureLets start out at room temperature

Show a normal thermometerShow an electronic thermometer Brownian Motion

MilkMicroscopeGlassWeb-CamBrownian motion observed on 1 3 micron particles of fat in milk.Brownian MotionNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %

Melting IceAnd then get a little bit colderPhoto credit http://www.cepolina.com/freephoto/ Room Temperature(about 20 C) Melting Ice(0 C)Ice melts Hand out ice and ask people for their observations. Infallibly the words cold and wet will be produced!

Use this as the link to the next slideMelting IceWhat happens when an ice cube touches your hand?Melting Ice

Ice melts

Hand out ice and ask people for their observations. Infallibly the word cold and wet will be produced!

Use this as the link to the next slideHeat TransferHot ObjectCold ObjectWhat happenswhen they come closer?Ice melts

The basic phenomenon is that when faster things hit slower things then the slower things tend to speed up and the faster things slow down.

Remind people of the previously mentioned idea that temperature is a measure of the speed of atomic motionsHeat TransferWhat happens when a fast moving atom hits a slow moving atom?

Ice melts

The basic phenomenon is that when faster things hit slower things then the slower things tend to speed up and the faster things slow down.

Remind people of the previously mentioned idea that temperature is a measure of the speed of atomic motionsWhy did you feel cold and wet?

Water molecules in the ice speed up and escape the electrical attraction of their neighboursCauses change of state from solid to liquid

Atoms and molecules in your hand slow downChanges the rate at which special cells to send electrical signals to your brain - interpreted as a too cold messageIce melts

The basic phenomenon is that when faster things hit slower things then the slower things tend to speed up and the faster things slow down.

Remind people of the previously mentioned idea that temperature is a measure of the speed of atomic motionsA short cold storySolid Carbon Dioxide and the balloonNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %Liquid nitrogenGetting coldRoom Temperature (about 20 C)Melting Ice (about 0 C)Solid CO2(-79.2 C)Much colder now Dry ice - Solid Carbon DioxideCarbon dioxide is unusual in that it transforms straight from the solid state to the gaseous state

Notice the fantastic expansion of the CO2 (by a factor of about 1000!) as it transforms from solid to gas Dry ice - Solid Carbon DioxideThats a million million!

Stupendous numbersMolecules travel around 500 metres per second: 1000 miles per hourEvery atom in the surface of the balloon is struck about 1012 times per secondThe figures correspond to room temperature

Did you do your homework?The coldest place on Earth?The figures correspond to room temperature The phases of matterSolids, liquids and gasesNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %Solids, liquids and gasesSolids, liquids and gases are called phases of matterSolidGasLiquidevaporateNot so normalmeltevaporatemeltNormalSolidGassublimatePlasmaPlasmaand plasmasThere are three familiar phases of matter.A caricature of a solidVery strong interactions between electrons in the outer parts of atomsA caricature of a liquidVery strong interactions between electrons in the outer parts of atomsA caricature of a gas hitting a wall Very strong interactions between electrons in the outer parts of atomsA caricature of a plasma-+-+-Very strong interactions between electrons in the outer parts of atomsSolids, liquids, and gases

The Institute of Physics and the National Physical Laboratory are joint sponsors of the Virtual Physical Laboratory for schools in the United Kingdom and the Republic of Ireland.Schools and colleges are able to receive a complimentary copy of the CD-ROM and a free site licence if they attend a demonstration event.For details of the next events, please contact Gary Williams from the IoP (gary.williams@iop.org) or Sam Gresham at NPL (sam.gresham@npl.co.uk)

Liquid nitrogenGetting coldMuch colder now Liquid nitrogenGetting coldRoom Temperature (about 20 C)Melting Ice (about 0 C)Solid CO2(-79.2 C)Liquid Nitrogen (about -196 C)Much colder now Another short cold storyLiquid Nitrogen and the balloonNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %Liquid nitrogen (2)At 20 C molecules travel at around500 metres per second: 1000 miles per hourAt -196 C molecules travel at about half this speed:250 metres per second: 500 miles an hourUnderstanding the liquid nitrogen demonstration requires one to understand that the inflation of a balloon is the result of competition between molecules striking the balloon from inside and outsideAnd its not just balloonsThe magnetic properties of terbiumDemonstration shows the effect of temperature on the magnetism of Terbium

This is actually an extremely complicated topic, but the idea of order / disorder sort of covers it pretty well Magnetic AtomsAs many electrons orbit the atom in one sense as in another Atom MagneticAtomSome electron orbits are unpairedRepresentation Axis of orbitsNSBrings out the idea of competition between order and disorder The effect of temperatureLow TemperatureHigh TemperatureBrings out the idea of competition between order and disorder So what happens if you keep getting colder?If the jiggling gets slower and slower then eventually atoms stop jigglingThis corresponds to the lowest conceivable temperatureAbsolute zero

Cooling this down allows all kinds of interesting ordered states to manifest themselvesMagnetismSuperconductivitySuperfluidity

Lord Kelvin (William Thompson)To measure is to knowIf you can not measure it, you can not improve itHeavier than air flying machines are impossibleRadio has no futureX-rays will prove to be a hoax

http://www-gap.dcs.st-and.ac.uk/~history/Mathematicians/Thomson.html

We named our son Kelvin after this great, if slightly bonkers. manAbsolute TemperaturekelvinUsed by scientists - I wont mention it again.

The size of one degree kelvin is the same as the size a degree celsius, but the zero of the scale is offset to the true zero of temperature.

And now lets start getting warmNormal body temperature for all mammals is 37 C

Temperature ofMammals(about 37 C)Room Temperature (about 20 C)Melting Ice (about 0 C)Solid CO2(-79.2 C)Liquid Nitrogen (about -196 C)Absolute Zero(-273.15 C)Much colder now The Body Temperature of AnimalsAnimalTemperature(C )Range(C )Horse 38.0 0.5Dog38.2 1.0 Cat38.5 0.7Whale 37.0 ?Rat38.5 0.5Guinea Pig38.2 1.0

Photo Credit http://www.graficworld.it/public/photos/cat-dog-19.jpg

All sources of this data were pretty unreliable, except for Whale Data from a dolphin researcher

http://www.graficworld.it/public/photos/cat-dog-19.jpg

That is, if the average energy of molecular jiggling is only 1% different (on the kelvin scale) then you will die.

NPL does a fair amount of work validating the performance of medical thermometers And warmer stillWater boils at 100 C

Temperature ofMammals(about 37 C)Room Temperature (about 20 C)Melting Ice (about 0 C)Solid CO2(-79.2 C)Liquid Nitrogen (about -196 C)Absolute Zero(-273.15 C)Water boils100 C

100 CThe Leidenfrost EffectWater boils at 100 CWhen it touches a very hot surface, it turns immediately to a vapour which causes droplets to float on a bed of vapour.Photo credithttp://www.astro.su.se/~magnusg/photogallery.htmlWhen water boils it transforms from liquid to gaseous state.

Thats when the jiggling of the molecules becomes so frantic that they escape from their mutual attraction Break time ActivityGo forth, and be amusedTake care. Liquid Nitrogen and solid CO2 are cold and can give severe frostbite.

BalloonsIce CreamThermal CameraHovercraftNow its the breakGetting hotterMuch hotterNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %And how hot is a candle flame?Guess!

The temperature of air from a hair dryer actually varies quite a bit

It can be quite high, certainly enough to damage your skin

And how does it get so hot!? A paperclips nightmareThe magnetic properties of ironDemonstration shows the effect of temperature on the magnetism of Terbium

This is actually an extremely complicated topic, but the idea of order / disorder sort of covers it pretty well The effect of temperatureLow TemperatureHigh TemperatureBrings out the idea of competition between order and disorder Increasing the random motion of the iron atoms destroys the magnetically ordered state

Comparing Iron and Terbium

Its interesting that there is a large ball of iron in the centre of the Earth - but it cant be magnetic because its too hot.Increasing the random motion of the iron atoms destroys the magnetically ordered stateMagnetism is a low temperature phenomenonEven when the low temperature is quite high!

Comparing Iron and Terbium Magnetism of Terbium destroyed around -100 C Magnetic Non-magnetic Magnetic Non-magnetic Terbium Iron Magnetism of Iron destroyed around 780 C The phenomena we saw in iron and terbium can be understood as part of the same frameworkThe hottest things in your house are your light bulbs!They become white hot 2500 C in a fraction of a secondGetting hotter stillI find the phenomena that occurs inside a light bulb quite astonishing.

The colour of a star depends upon its surface temperature

Stars

Picture Credit:Richard Powellhttp://www.atlasoftheuniverse.com/me.html

I find the phenomena that occurs inside a light bulb quite astonishing.http://en.wikipedia.org/wiki/Image:Hertzsprung-Russell_diagram_Richard_Powell.png

Picture from Richard Powellhttp://www.atlasoftheuniverse.com/me.html ReminderAnd how does this link to the first two weeks?Notice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %Lets remind ourselves about atoms (1)The internal structure of atomsElectronsorbit around the outside of an atomvery lightpossess a property called electric chargeNucleusoccupies the centrevery tiny and very heavyprotons have a property called electric chargeneutrons have no electric charge Despite their miniscule size, we know about their internal structure from several experiments but importantly we can look at the light which emerges from atoms.Lets remind ourselves about atoms (2)Nuclei (+) attract electrons (-) until the atom as a whole is neutralThe electrons repel each other They try to get as far away from each other as they can, aand as near to the nucleus as they canElectronsElectrons possess 1 unit of negative chargeNucleusprotons possess 1 unit of positive chargeneutrons have no electric charge A word about frequency (1)1 oscillation per second is called 1 hertz

The unit is named for Heinrich Hertz who first investigated the properties of electromagnetic waves.

http://www.fisica.ufpb.br/graduacao/selos.htm For pictures of stamps of famous scientistsA word about frequencyoscillations per secondis called a1000(a thousand) (103) kilohertz (kHz)1000000 (a million) (106) megahertz (MHz)1000000000 (a billion) (109) gigahertz (GHz)1000000000000 (a trillion) (1012) terahertz (THz)1000000000000000 (a million billion) (1015) petahertz (PHz)MicrowavesFrom 0.8 GHzto 1000 GHz11011021031041051061071081091010101110121013101410151016101710181019102010211022Radio & TVInfra RedMicrowavesGamma-RaysX-RaysUltra VioletFrequency (Hertz)1000 THz (Blue)400 THz (Red)Electromagnetic spectrum Notice how stupendously large is the range of frequencies, and how narrow is the range of frequencies of visible light.Remember how different a millimetre is from a kilometre? Well think how different a radio wave (1 million oscillations per second (say)) is from a light wave, (1000 million million oscillations per second ) WOW!Visible lightNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %SpectraLast week we saw that different sources of light have quite different spectraDiscrete (made of lines) Continuous (Like a rainbow)

We make light by simply hitting an atom: hardStrike it with an other atom Strike it with an electronShake it with an electric wave

Link to last weeks contentLight from atomsIf an atom or molecule is unconstrained then When it is hit, it rings like a bellAtoms ring at their natural frequency: resonanceEach type of atom vibrates in a characteristic manner.

By unconstrained I mean that there are no other molecules or atoms nearby to get in the way. Usually that means the molecules are in a gas. But it is possible to allow these kinds of oscillations in solids, but it is quite unusual. It is particularly possible for atoms at surfaces

The demosnstration here uses a tuning forks of different sizesThe frequency of oscillation varies with the size and material of the tuning forkBy analogy, the frequency of oscillation of atoms varies with the size of the atom and the strength of the electric forces within the atoms

If an atom or molecule is constrained then it cannot ring clearly.The light which emerges has a mixture of all possible frequenciesThe balance of colours in the spectrum depends on how fast the atoms are jiggling i.e. on temperature.Light from atoms in solids

The atoms in a sold constantly jiggle and jostle each otherInfra Red LightNotice the massive expansion of the CO2.

10 g of CO2 solid has a volume of about 0.01/ 1562 kg/m^3 = 6 cc

In the gaseous state at around 15 C this increases to

10 g of CO2 gas at around 15 C has a volume of about 0.01/ 1.87 kg/m^3 = 5 litres

Molecular WeightMolecular weight : 44.01 g/molSolid phaseLatent heat of fusion (1,013 bar, at triple point) : 196.104 kJ/kgSolid density : 1562 kg/m3Liquid phaseLiquid density (at -20 C (or -4 F) and 19.7 bar) : 1032 kg/m3Liquid/gas equivalent (1.013 bar and 15 C (per kg of solid)) : 845 vol/volBoiling point (Sublimation) : -78.5 CLatent heat of vaporization (1.013 bar at boiling point) : 571.08 kJ/kgVapor pressure (at 20 C or 68 F) : 58.5 barDensity & temperature calculation of the liquid phaseGiven the pressure (in bar), this module calculates the temperature and the density of the liquid phase on the liquid-gas equilibrium curveEnter the pressure in bar (between 7 and 26) barCritical pointCritical temperature : 31 CCritical pressure : 73.825 barCritical density : 464 kg/m3Triple pointTriple point temperature : -56.6 CTriple point pressure : 5.185 barGaseous phaseGas density (1.013 bar at sublimation point) : 2.814 kg/m3Gas density (1.013 bar and 15 C (59 F)) : 1.87 kg/m3Compressibility Factor (Z) (1.013 bar and 15 C (59 F)) : 0.9942Specific gravity (air = 1) (1.013 bar and 21 C (70 F)) : 1.521Specific volume (1.013 bar and 21 C (70 F)) : 0.547 m3/kgHeat capacity at constant pressure (Cp) (1.013 bar and 25 C (77 F)) : 0.037 kJ/(mol.K)Heat capacity at constant volume (Cv) (1.013 bar and 25 C (77 F)) : 0.028 kJ/(mol.K)Ratio of specific heats (Gamma:Cp/Cv) (1.013 bar and 25 C (77 F)) : 1.293759Viscosity (1.013 bar and 0 C (32 F)) : 0.0001372 PoiseThermal conductivity (1.013 bar and 0 C (32 F)) : 14.65 mW/(m.K)MiscellaneousSolubility in water (1.013 bar and 0 C (32 F)) : 1.7163 vol/volConcentration in air : 0.03 vol %11011021031041051061071081091010101110121013101410151016101710181019102010211022Radio & TVInfra RedMicrowavesGamma-RaysX-RaysUltra VioletFrequency (Hertz)Electromagnetic spectrum 2500 C800 C20 CThe filament of a normal light bulb is heated to about 2500 celsius to make it give off white light When something is at about 800 celsius: its red hotWhen its colder, it gives off only infra-red light. We cant see this light but we can detect it.

Notice how stupendously large is the range of frequencies, and how narrow is the range of frequencies of visible light.Remember how different a millimetre is from a kilometre? Well think how different a radio wave (1 million oscillations per second (say)) is from a light wave, (1000 million million oscillations per second ) WOW!

Infra Red Light from constrained molecules

Infra-Red lightObjects at around ambient temperature emit infra-red light with a wavelength of about 0.01mm. For example:Our bodiesThe Earth

Well be around to measure your temperature by capturing the radiation you emit in just a minuteWhat happens if you knock a molecule?If a molecule is hit, the atoms within a molecule vibrate. Because atoms are thousands of times heavier than electrons they ring with a much lower frequencies.The light given off is in the infra red range of the spectrum.

H20 Once again think of the the tuning fork

The fact that molecules ring or resonate in the infra red is critically important for the property of the atmosphere and the existence of the greenhouse effectInfra red light from unconstrained moleculesDifferent types of molecular jiggling occur at different frequencies

Water H20

Carbon dioxide C02

Water molecule animations from

http://www.lsbu.ac.uk/water/vibrat.htmlSummaryHeatHeat is the ceaseless disordered motions of atoms and moleculesTemperature is a measure of the speed with which atoms and molecules moveAtoms and molecules are electrical in their nature, and as they move they are constantly emitting and absorbing electromagnetic radiationA summary of things so far Electromagnetic waves

ElectricityHeat

How it all fits togetherAtomsAnd a pictorial summary for those who appreciate things that way.

How it all fits together

And a pictorial summary for those who appreciate things that way.Homework?HOMEWORK!HomeworkResearch:

Please find one fact about global warming

(Write it down on a piece of paper and Ill collect the facts at the start of the next session)

ResearchOne minute feedbackOn the back of your handouts!Rip off the last sheetPlease write down what is in on your mind RIGHT NOW!A question? OKA comment? OKA surprising thought in your mind? Id love to hear it!On-line Resourceswww.protonsforbreakfast.org This PowerPoint presentation.Handouts as a pdf file

blog.protonsforbreakfast.org Links to other sites & resourcesMe going on about things

See you next weekto discuss GlobalWarming! GoodnightGoodnight!

Room Temperature

(about 20( C)

Balloon

Spoon

Solid CO2

Tie Balloon

Room Temperature

(about 20 (C)

Melting Ice

(0 (C)

Solid CO2

(-79.2 (C)

Liquid Nitrogen

(-196 (C)

Absolute Zero

(-273.15 (C)

Room Temperature

(about 295 kelvin)

Melting Ice

(273.15 kelvin)

Solid CO2

(193.4 kelvin)

Liquid Nitrogen

(77 kelvin)

Absolute Zero

(0 kelvin)

Room Temperature

(about 20 (C)

Melting Ice

(0 (C)

Solid CO2

(-79.2 (C)

Liquid Nitrogen

(-196 (C)

Absolute Zero

(-273.15 (C)

Body Temperature

(37 (C)

Water Boils

(100 (C)

Magnetism of Iron destroyed

(780 (C)