Thermal T6-T9 Flashcards
Define all of the terms in ‘pV = nRT’.
P = pressure
V = volume
N = number of moles
R = molar mass constant 8.31 K-1 mol-1
T = temperature
Define all of the terms in ‘pV = NkT’.
P = pressure
V = volume
N = number of molecules
k = the Boltzmann constant = 1.38 × 10–23 J K–1.
T = temperature
Define all of the terms in ‘pV = ⅓ nmcrms2’.
P = pressure
V = volume
N = number of molecules
C = root mean square speed
Define ‘mole’.
A mole is the mass of the substance that contains a number of particles that is equal to the Avogadro’s constant, Na, 6.02 x 10^23.
Define ‘molar mass’.
The molar mass is the mass of one mole of that substance.
State 9 of the ‘ideal gas assumptions’
All molecules of a gas are identical.
The gas contains a larger number of molecules.
The molecules have negligible volume compared with the volume of the gas.
The molecules move in random motion (direction and speed).
Attraction between molecules is negligible.
Collisions between molecules or a wall are elastic.
The molecules move in a straight line between collisions.
The forces acting during collisions act for a short time, relative to the time between collisions.
How does ‘kinetic theory’ explain Boyle’s law (pV = constant)?
The pressure of the gas increases when the volume reduces because: The molecules travel less distance between impacts. So the impacts with the wall become more frequent.
How does ‘kinetic theory’ explain the pressure law (P/T = constant)?
The pressure of the gas increases as the temperature rises because: The molecules have a larger average speed. So the impacts on the wall are harder and more frequent.
Define crms.
The root mean square speed is proportional to the pressure a gas applies to the wall of the container. It is the mean speed corresponding to the mean KE of the molecules in a gas.
State and explain how the mean-square speed of heavier atoms in a mixture of a gas compares to lighter atoms and the same temperature…
Mass is inversely proportional to the mean-square speed, so will be less at the same temperature.
What is Boyle’s Law?
pV = constant, therefore pressure is proportional to volume.
What is Charles’ Law?
For constant pressure, volume is proportional to the temperature, has to be in kelvin.
What is the Pressure Law?
For constant volume, pressure is proportional to the temperature, has to be in kelvin.
What is an isothermal change?
A change at a constant temperature.
What is 0 kelvin in degrees Celsius?
-273^oC.
