Measurement of Molar Quantities 1 mole of a substance contains
6.02 x 10 23 particles.
Slide 3
Ideal Gas kinetic theory Gases consist of small particles
(molecules) which are in continuous random motion The volume of the
molecules present is negligible Intermolecular forces are
negligible Pressure is due to the gas molecules colliding with the
walls of the container
Slide 4
No gas behaves ideally. All gases deviate to some extent from
ideal behaviour. They are described as real gases
Slide 5
The greatest deviation from ideal behaviour occurs when the gas
is subjected to _________temperature and _______ pressure low
high
Slide 6
Real Gases deviate from Ideal Gas Behaviour at low
temperatures, the gas molecules move slowly, so they do attract
each other (strengthen the intermolecular forces between
molecules/atoms) at high pressures the gas molecules are forced
closer together What happen to the gas at low temperature? Gas
condenses into liquid at low temperature Real gases do have
attractive forces between the molecules and they do occupy some
space Do not exactly obey the laws
Slide 7
Avogadros Law Equal volumes of ideal gases measured at the same
temperature and pressure contain the same number of molecules.
Slide 8
Molar Volume of a Gas Avogadros Law states that equal volumes
of different gases at the same temperature and pressure contain the
same number of moles. V n (constant P, T) 1 mole of any gas will
occupy the same volume at the same temp and pressure known as molar
vol of a gas.
Slide 9
Boyles Law Boyle's law or the pressure-volume law states that
the volume of a given amount of gas held at constant temperature
varies inversely with the applied pressure when the temperature and
mass are constant. ( constant T, n) The product of the initial
volume and pressure is equal to the product of the volume and
pressure after a change in one of them under constant temperature.
Animation
Slide 10
Charless Law Charless law states that the volume of a given
amount of gas held at constant pressure is directly proportional to
the Kelvin temperature. ( constant P, n) Initial and final volumes
and temperatures under constant pressure can be calculated.
Animation
Slide 11
Gay-Lussac's Law Gay-Lussacs law states that the pressure of a
given amount of gas held at constant volume is directly
proportional to the Kelvin temperature. ( constant V ) Initial and
final volumes and temperatures under constant pressure can be
calculated.
Slide 12
Gay-Lussac's Law
Slide 13
The Ideal Gas Law The previous laws all assume that the gas
being measured is an ideal gas, a gas that obeys them all exactly.
But over a wide range of temperature, pressure, and volume, real
gases deviate slightly from ideal. The different variables for a
gas are related by the idea gas law: 1 mole of ideal gas occupies
22.4 dm 3 ( 2.24 x 10 -2 m 3 ) at 273K and 1.013 x 10 5 Pa (1 atm)
pressure [stp]
Slide 14
Ideal Gas Equation P = pressure in Pa (Nm -2 ) ( 1 atm = 1.013
x 10 5 Pa) T = absolute temperature in K V = volume in m 3 ( 1 cm 3
= 1 x 10 -6 m 3 ) n = number of moles R = gas constant = 8.314 JK
-1 mol -1 Real gases have some attractive forces between particles
the particles themselves do occupy some space So they do not
exactly obey the laws. A gas behaves most like an ideal gas at
_____temperature and _____pressures. high low
