5.1 Thermal Physics Flashcards
What is the triple point of a substance
One specific temperature and pressure where the three phases of matter of that substance can exist in thermal equilibrium
What is the triple point of water
0.01°C 0.61kPa
What is meant by thermal equilibrium
There is no net transfer of thermal energy between the phases
What is temperature
A measure of the hotness of an object on a chosen scale. The hotter the object the higher the temperature
What does the 0th law of thermodynamics tell us
If two objects are each in thermal equilibrium with a third then all three are in thermal equilibrium with each other
What are the two fixed points on the Celsius temperature scale
Freezing point (0°C)
Boiling point (100°C)
Why is the Celsius scale not perfect
The fixed points vary significantly depending on the surrounding atmospheric pressure
What are the 2 fixed points in the absolute scale of temperature
The triple point of water and absolute zero
What is the SI base unit of temperature on the absolute scale
Kelvin (K)
What is absolute zero
The lowest possible temperature- substances have zero energy
What is the relationship between temperature in °C and K
A change of 1K is the same as a change of 1°C. There are exactly 273.16 increments between absolute zero and the triple point of water T(K)= θ(°C) + 273
What is meant by the kinetic model
The kinetic model describes how all substances are made up of atoms or molecules which are arranged differently depending on the phase of the substance
What are the atomic or molecular features of a solid
-Atoms or molecules are regularly arranged and packed close together
-strong electrostatic forces of attraction- holding them in fixed positions
-can vibrate so have kinetic energy
What are the atomic or molecular features of a liquid
-atoms or molecules are still very close together
-more kinetic energy then solids
-can change position and flow past eachother
What are the atomic or molecular features of a gas
-atoms or molecules have more kinetic energy then liquids
-they are much further apart
-they are free to move past eachother as there as are negligible electrostatic forces between them
-they move randomly with different speeds in different directions
