Celsius & Kelvin Temperature Scales
Boiling pointof water
Freezing pointof water
Absolutezero
Celsius
100Celsiusdegrees
100oC
0oC
-273oC
Kelvin
100Kelvins
373 K
273 K
0 K
Temperature is Average Kinetic Energy
Fast Slow“HOT” “COLD”
Kinetic Energy (KE) = ½ m v 2
*Vector = gives direction and magnitude
Temperature Scales
Fahrenheit
212 oF
180 oF
32 oF
Celcius
100 oC
100 oC
0 oC
Kelvin
373 K
100 K
273 K
Boiling point of water
Freezing point of water
Notice that 1 kelvin degree = 1 degree Celcius1 kelvin degree = 1 degree Celcius
Kelvin Scale
blue
white
yellow
4300 K PIAA HID Bulb
5000 K PIAA Plasma Blue
5250 K Sunlight
4150 K PIAA Xtreme White
3800 K PIAA Super White
3200 K Halogen Bulb
2600 K Incandescent Bulb
Temperature Scales
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 136
Compare Celsius to Fahrenheit
oF – 32 = 1.8 oC
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 139
Converting 70 degrees Celsius to
Kelvin units.
oC + 273 = K
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 137
Temperature Scales
• Temperature can be subjective and so fixed scales had to be introduced.
• The boiling point and freezing point of water are two such points.• Celsius scale (oC)
– The Celsius scale divides the range from freezing to boiling into 100 divisions.
– Original scale had freezing as 100 and boiling as 0.
– Today freezing is 0 oC and boiling is 100 oC.
• Fahrenheit scale (oF)• Mercury and alcohol thermometers rely on thermal expansion
Thermal Expansion
• Most objects e-x-p-a-n-d when heated• Large structures such as bridges must be
built to leave room for thermal expansion• All features expand together
COLDHOT
Cracks in sidewalk.
Equal Masses of Hot and Cold Water
Thin metal wall
Insulated box Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 291
Water Molecules in Hot and Cold Water
Hot water Cold Water90 oC 10 oC
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 291
Water Molecules in the same temperature water
Water(50 oC)
Water(50 oC)
Zumdahl, Zumdahl, DeCoste, World of Chemistry 2002, page 291
Heat versus Temperature
Kinetic energy
Fra
ctio
ns o
f pa
rtic
les
lower temperature
higher temperature
TOTALKinetic ENERGY
= Heat= Heat
Molecular Velocities
speed
Fra
ctio
ns o
f pa
rtic
les many different molecular speeds
molecules sorted by speed
the Maxwell speed distribution
http://antoine.frostburg.edu/chem/senese/101/gases/slides/sld016.htm
Temperature vs. Heat
Measuredwith a
Calorimeter
TotalKineticEnergy
Joules(calories)
Measuredwith a
Thermometer
AverageKineticEnergy
oCelcius(or Kelvin)
Alike Different
A Propertyof
Matter
HaveKineticEnergy
Heat
Different
Topic Topic
Temperature
Conservation of Matter
Reactants yield Products
Heavy Metal Poisoning
Exposure to mercurymade the Hatter “mad”.
Eating chips of lead paint causes brain damage.
TREATMENT: Chelation therapy EDTA (ethylenediamine tetra acetic acid)
Arsenic treated lumber.‘Green-treated’ woodwill not rot outdoors for 50 years.