2. Microscopic Atoms
Atoms in matter are in constant motion.
Interaction of atoms determines the state of matter.
Solid Liquid Gas
• Atoms vibrate • Atoms close, • Atoms apart,
in a nearly but free to freely moving in
fixed position move around the volume
3. Macroscopic Properties
There are about 5 x 1024
Microscopic properties:
atoms in a golf ball.
We track its motion as a mass, position, velocity, energy
whole, not as atoms.
Density and pressure apply Macroscopic properties:
to the whole object, not the
atoms. mass, position, velocity, energy
These are macroscopic and
properties.
density, pressure, temperature
4. Hot and Cold
Temperature is a
macroscopic property of
matter.
• Based on statistics
• Doesn’t generally apply to
single atoms
Hot matter has more energy
per atom on average than
cold matter.
• Single atoms may have less
energy in a hot item
5. Thermal Contact
heater Two cups of water are in
contact.
• Heat one cup
• Compare macroscopic
properties
If they are the same they are
heater in thermal contact.
• eg. metal cups
If different they are insulated.
6. Thermal Equilibrium
Two systems have the same temperature if they are
in thermal equilibrium.
• Equilibrium between systems
• Measure of macroscopic properties
If two systems are not in thermodynamic equilibrium,
they are not in thermal contact.
7. Law Zero
If two systems are each in thermodynamic
equilibrium with a third system, then they are in
thermodynamic equilibrium with each other.
This is the Zeroth Law of Thermodynamics.
A is in thermal equilibrium with B.
A B C C is in thermal equilibrium with B.
Therefore, A is in thermal
equilibrium with C.
8. Gas Thermometer
A system with known macroscopic properties may be
placed in thermodynamic equilibrium.
A device that uses this is a thermometer.
This thermometer uses the
pressure of gas in a bulb.
The meter measures the height
in a manometer or barometer.
9. Kelvin
Temperature requires a 10-4 K Superfluid liquid helium
scale to compare different 4K Helium boils
systems. 77 K Air boils
The Kelvin (K) is the SI unit 273 K Water melts
of temperature.
373 K Water boils
• Based on behavior of water
• Linear pressure scale 630 K Mercury boils
• Not degrees Kelvin 1000 K Copper melts
6000 K Surface of the sun
P 106 K Solar corona
T = 273.16
P3 108 K Hydrogen bomb
10. Temperature Scales
For everyday temperatures The English system uses the
the Celsius scale (°C) is Fahrenheit scale (°F).
used.
Ice point at 1 atm is 32°.
Each °C is the same Boiling point at 1 atm is
magnitude as 1 K. 212°.
• The zero is different Each °F is 5/9 of a °C.
• 0 °C = 273.15 K
• Not quite T at P3
9
TF = TC + 32
5
11. Body Temperature
Normal body temperature is The general formula applies
98.6 °F. What is the for a conversion between
equivalent in °C and K? scales.
• TC = (5/9)(TF – 32)
If your fever is 101.6 °F, by • (5/9)(98.6 – 32.0) = 37.0 °C
how much has it risen in °C • T = TC + 273.15 = 310.2 K
and K?
The difference use the
fractional change.
• ∆TC = (5/9) ∆TF
• (5/9)(101.6 – 98.6) = 1.7 °C
• ∆T = ∆TC = 1.7 K
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