2. Thermal Physics Flashcards
Absolute Zero:
The lowest possible temperature of a system, where no heat
remains and the particles in the system have no kinetic energy.
Avogadro Constant:
The number of particles that make up one mole of any gas
Boyle’s Law:
The pressure of an ideal gas is inversely proportional to its volume when held at constant temperature.
Brownian Motion:
The random motion of particles
Small particles (such as pollen or smoke particles) suspended in a liquid or gas are observed to move around in a random, erratic fashion
Charles’ Law:
The volume of an ideal gas is directly proportional to its absolute
temperature when held at constant pressure.
Internal Energy:
The sum of the randomly distributed kinetic and potential energies of the particles in a given system.
Kelvin Scale:
An absolute temperature scale that starts at absolute zero (0K = -273°C).
Pressure Law:
The pressure of an ideal gas is directly proportional to its absolute temperature, when the volume is fixed.
Specific Heat Capacity:
The amount of energy required to increase the temperature of 1kg of a substance by 1 Kelvin.
Specific Latent Heat of fusion:
The amount of energy required to change the state of 1kg of a material from the solid state to the liquid state without a change of temperature.
Describe what happens in a state change.
During a state change, the potential energy of the system is changing but the kientic energy is not.
As the temperature of the gas increases:
The average particle speed increases.
The average kinetic energy of the particles increases.
The distribution curve becomes more spread out.
What does the graph ot 200k and 500k of number of particals ant speccific speeds?
What assumptions are made in kinetic theory? eight points
-All molecules of the gas are identical.
-The gas contains a large number of molecules.
-The molecules have a negligible volume compared with the volume of the container (i.e. they act as point masses).
-The molecules continually move about randomly.
-Newtonian mechanics apply (i.e. the motion of the molecules follows Newton’s laws).
-Collisions between molecules themselves or at the walls of a containe are perfectly elastic (i.e. kinetic energy is conserved).
-The molecules move in a straight line between collisions.
-The forces that act during collisions last for much less time than the time between collisions.
Specific latent heat of vaporisation is greater than specific later heat of fusion because:
Any two from:
• More energy has to be supplied to separate molecules (liquid to gas) than the break the solid bond between them (solid to liquid);
• For vaporisation, work is done against the atmospheric pressure;
• There is a greater change in potential energy from liquid to gas than from solid to a liquid;
