mass
'no magic to the mole'
amount
molar mass
concentration
solution volume
gas volume
molar gas volume
Avogadro
constant, L
number of
entities, N
Now try the following question.
E4. THE EXPERIMENTAL GAS LAWS
As the particles in a dilute gas, i.e., one at low pressure, are so far apart they are essentially independent of each other – the behaviour of a gas can be described without referring to the nature of the individual molecules. The gaseous state is therefore the simplest; meaningful measurements were being made as long ago as the 1660s.
4.1 BOYLE'S LAW (1662)
E4.2 AMONTONS' LAW (1702) aka GAY-LUSSAC'S LAW or UNIVERSAL PRESSURE LAW
This law describes the manner in which the pressure of a fixed mass of gas at constant volume varies with the absolute temperature:
E4.3 CHARLES' LAW (1787)
volume, V
0
273.15
pressure, P
3
pressure, P
1
pressure, P
2
absolute temperature, T / K
Charles’ law plots based on thermodynamic temperature, and so the Kelvin temperature scale, once extrapolated towards lower values, have x-intercepts at zero kelvin, i.e., 0 K, otherwise known as absolute zero.
ASIDE: Absolute zero is the lower limit of the thermodynamic temperature scale and commonly thought of as the lowest temperature possible. Matter (solid) at absolute zero is in its ground state, the point of lowest internal energy. Cryogenics has achieved temperatures extremely close to absolute zero, where matter exhibits quantum effects such as superconductivity and super-fluidity. The lowest ever recorded temperature for matter is about 100 picokelvins (pK), or 0.000 000 000 1 K.
E4.4 THE COMBINED GAS LAWS
(The ideal gas equation pV = n R T is dealt with in section E.10 from pages 36-42).