GASES, LIQUIDS & SOLIDS
3 states of matter: solid, liquid, gas (+plasma-ionised gas at high temp)

PARTICLES IN SOLID	PARTICLES IN LIQUID	PARTICLES IN GAS
closely packed together + attracted by strong forces of attraction	quite close together, not as close together as in solid, attracted by forces weaker than in solid	far apart, attracted by weaker forces of attraction
regularly arranged in lattice structure	not orderly arranged	not orderly arranged, move about randomly
least KE > not enough to overcome attractive forces > particles only rotate & vibrate at fixed positions	enough KE to overcome attractive forces while in close proximity > particles rotate, vibrate & translate from 1 place to another	large KE > overcome attractive forces > particles vibrate, rotate & translate from 1 place to another freely

Molecular motion of atoms or molecules:
-vibrational: vibrate at fixed position
-rotational: spin around at fixed position
-translational: move from 1 place to another

GAS:real (in practice) + ideal (in theory)
Ideal gas: according to kinetic theory, an ideal gas have no attractive forces bet gas particles & the gas particles do not occupy any space (negligible compared to system)
Ideal gas equation: based on kinetic theory:
pV = nRT [p = pressure-Pa, V = vol-m³, n = # of moles, T = absolute temp-K, R = gas constant] (all ideal gases obey equation)

Calculation of R based on fact that "1 mole of gas occupies 22.5 dm³ at stp"
R = 8.31441 JK^-1mol^-1 [for vol: m³, pressure: Pa, temp: K]
R = 82.053 cm³atmK^-1mol^-1 [for vol: cm³, pressure: atm, temp: K] [1 atm = 101235 Pa]
R = 1.9871 calK^-1mol^-1

pV=nRT > pV = (m/M_r)RT > M_r = mRT/(pV)

Other gas laws (derived from ideal gas equation)
Boyle's Law (T: const > p ∝ 1/V)
pV = nRT = constant if T & n are kept constant


Charles's Law (p: const > V ∝ T)
pV = nRT > V/T = nR/p = constant if p & n are kept constant


Pressure Law (V const > p ∝ T)
pV = nRT > p/T = nR/V = constant if V & n are kept constant


Dalton's law of partial pressure: total pressure of a mixture of non-reacting gases is equal to the sum of the partial pressure of all the gases in the mixture > p_total = p'_A + p'_B + p'_C +.. [p'_A: partial pressure of gas A]
(partial pressure = pressure exerted by gas if it were to occupy whole volume alone)
pressure: due to bombardment of gas molecules against wall of container
Partial pressure in terms of mole fraction: partial pressure of a gas = mole fraction × total pressure

Deviation from ideal gas behaviour
real gases behave ideally at low pressure + high temp
low pressure: intermolecular forces of attraction: small as molecules are far apart, also vol of gas molecules is negligible compared to vol of space occupied by gas
high temp: molecules move fast past 1 another > forces of attraction negligible
eg: gases w/ low RAM/RMM w/ very weak Van der Waals force of attraction- H₂, N₂, He

real gases behave non-ideally at high pressure + low temp
high pressure: intermolecular forces of attraction: significant as molecules are close together, also definite vol of gas molecules is significant compared to vol of space occupied by gas
low temp: molecules move slowly past 1 another > appreciable forces of attraction appear
eg: gases w/ larger RAM/RMM w/ strong intermolecular forces of attraction- NH₃, SO₂, CO₂, NO₂ (these gases are easily compressed & liquified due to strong intermolecular forces of attraction under high pressure)


Gases, liquids & solids part 2


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