gas laws
laws of physics relating the temperature, volume and pressure of a fixed amount of a gas: Boyle’s law, Charles’ law and Gay-Lussac’s law
pressure, P
force acting normally per unit area: pressure = force/area (SI unit: pascal Pa), 1 Pa = 1 Nm⁻²
amount of gas
the quantity of gas in a container, expressed in term of the number of particles it contains
pascal
derived SI unit for pressure, 1 Pa = 1 Nm⁻²
atmospheric pressure
pressure due to the motions of the gas molecules in the air, can be considered as being due to the weight of the air above an area of 1 m², acts equally in all directions
amount of a substance, n
measure of the number of atomic-scale particles (atoms or molecules) it contains (SI unit: mole)
mole, mol
SI unit of amount of substance (fundamental)
Avogadro constant, Nₐ
the number of particles in 1 mole of a substance: 6.02 × 10²³
molar mass
the mass of a substance that contains 1 mole of its defining particles
circuit breaker
electromagnetic device used to disconnect an electrical circuit in the event of a fault
isothermal
occurring at constant temperature
Boyle’s law
pressure of a fixed amount of gas is inversely proportional to volume (at constant temperature)
Gay-Lussac’s law
for a fixed mass of gas with a constant volume, the pressure is proportional to the kelvin temperature
Charles’ law
volume of a fixed amount of gas is proportional to absolute temperature (at constant pressure)
empirical
based on observation or experiment
universal (molar) gas constant
the constant, R, that appears in the equation of state for an ideal gas (PV = nRT), R = 8.31 Jk⁻¹mol⁻¹
equation of state for an ideal gas, PV=nRT
describes the macroscopic physical behaviour of ideal gases, also called the ideal gas law
piston
a solid cylinder that fits tightly inside a hollow cylinder, trapping a fluid, designed to move as a result of pressure differences
PV diagram
a graphical way of representing changes to the state of a gas during a thermodynamic process
ideal gas
gas which obeys the ideal gas law perfectly, the microscopic particle model of an ideal gas makes several important assumptions about the particles and their motions
average value
any single number used to represent a quantity which is varying
range (data)
spread of data from smallest to largest values
anomalous
different from the pattern of other similar observations
outlier
a value which is signficantly different from the others in the same data set
mean
a certain type of average: the sum of all of the numbers divided by the number of values involved
dimensional analysis
method of checking if an equation may be correct, the units (dimensions) of all terms should be the same
internal energy of an ideal monoatomic gas, U
the sum of the random translational kinetic energies of all the molecules
real gases
modelling of gas behaviour is idealized, real gases do not behave exactly the same as the model of an ideal gas