Thermal Physics Flashcards
State the Zeroth Law of Thermodynamics.
If A is in thermal equilibrium with B, and B is in with thermal equilibrium with C, then A is in
thermal equilibrium with C.
Define Thermal equilibrium.
Thermal equilibrium is a situation in which there is no net exchange of energy when 2 objects
are placed in thermal contact.
State Charles’s Law.
The volume of a fixed amount of gas at constant pressure is directly proportional to its
absolute temperature.
State Boyle’s Law.
The pressure of a fixed amount of gas at constant temperature is inversely proportional to its
volume.
State the Pressure Law.
The pressure of a fixed amount of gas at constant volume is directly proportional to its
absolute temperature.
Define the Ideal Gas equation.
An ideal gas is a gas that will obey the ideal gas equation, for all thermodynamic temperature,
volume and pressure when it is a fixed mass of gas,
pV = nRT,
where p is the pressure of the gas, V is the volume of the container, n is the amount of gas
in number of moles, R is the molar gas constant, and T is the temperature of the gas.
What are the 5 assumptions of the kinetic theory of gases?
- Large number of molecules in random motion:
- Identical sphere: Negligible forces of intermolecular attraction
- Collisions of the gas molecules with one another and with the walls of the container
are perfectly elastic. - Hard: Duration of collisions is negligible compared with the time interval between
collisions - The volume of the gas molecules is negligible compared to the volume of the
container, which is the volume of the gas.
What is the formula of pressure exerted by a gas on a wall?
p = ⅓Nm/V < c^2 > = ⅓ρ < c^2 >, ρ = density of gas, N = total number of molecules in the gas, V = volume of container, m = mass of one molecule, < c^2 > = mean square speed of molecule.
What is the formula for the mean kinetic energy of 1 ideal gas molecule?
= ½m < c^2 >
What is the internal energy of an ideal gas system with N molecules?
U = 1½PV = 1½NkT = nRT
Define the internal energy of a system.
Internal energy of a system is the sum of the random distribution of microscopic kinetic energy (due to the random motion of particles) and microscopic potential energy (due to intermolecular forces) of the system.
Define specific heat capacity and its formula.
It is the energy per unit mass required to raise the temperature of the substance by one unit of temperature.
Q = mcΔT Q = heat, m = mass, c = specific heat capacity, ΔT = change in temperature
Define specific latent heat of fusion.
The specific latent heat of fusion, Lf, is defined as the energy per unit mass required to change a substance from solid to liquid without a change in temperature.
Define specific latent heat of vapourisation.
The specific latent heat of vapourisation, Lv, is defined as the amount of heat required per unit mass to change a substance from the liquid state to the vapor state without any change in temperature.
State the First Law of Thermodynamics.
The increase in the internal energy of a system is the sum of the heat supplied to the system
and the work done on the system.
