Flashcards: H2 Chemistry 7 - Gaseous state

1. gas particles in constant state of random continuous motion

2. V_{gas particles} negligible compared to V_container

3. no IMF b/w gas particles

4. collisions b/w gas particles perfectly elastic, no loss of energy

5. average gas particles KE ∝ absolute temp(K)

real gases tend towards ideal behaviour @

high temp, low pressure

high temp, gas particles high KE >

sufficient energy to overcome IMF b/w gas particles

low pressure, V_gas large, gas particles spaced far apart >

V_{gas particles} negligible compared to V_container

V_gas small, gas particles closer tgt, V_{gas particles} significant compared to V_container

gas particles lower KE, have insufficient energy overcome IMF b/w gas particles, IMF become significant >

↑ IMF b/w gas particles, collision b/w particles < elastic >

V_gas ↓, gas particles close tgt w/ < space b/w them, IMF become significant

pV = nRT,

as V = RnT/p

p = gas pressure(Pa/Nm^-2)

V = V_gas in cubic metre(m³)

n = n_gas(mol)

R = molar gas constant(8.31JK^-1mol^-1)

T = gas temp(K)

in mixture of gases that don't react w/ EO, total pressure exerted by gaseous mixture = sum of partial pressures of each individual gas >

partial pressure of gas in mixture = pressure gas exerts on wall of container if it alone occupies container

@ constant temp, volume(V) of given mass of gas inversely ∝ to its pressure(p)

V ∝ 1/p; V = k/p

@ constant pressure, volume(V) of fixed mass of gas directly ∝ to absolute temp(T) in Kelvin

V ∝ T; V = kT

@ constant pressure & temp, volume(V) of gas directly ∝ to no. of moles of gas(n)

V ∝ n; V = kn

s.t.p. 0^oC/273K, 1 bar/10⁵ Pa

molar volume = 22.7dm³

r.t.p. 20^oC/293K, 1 atm/101325 Pa

molar volume = 24dm³

obeys pV=nRT under all conditions of temp & pressure

obeys all assumptions of kinetic theory of gases

pV = nRT ---(1)

n = mass / molar mass = m/M ---(2)

sub (2) in (1), get

M = mRT/pV

density, x = mass(g)/volume(m³)

x = m/V, so m = xV --- (1)

sub (1) in M = mRT/pV, get

M = x(RT/p), then

x(gdm^-3) = pM/RT

given gas A,

p_AV = n_ART --- (1)

p_totalV = n_totalRT --- (2)

(1)/(2), p_A / p_total = n_A / n_total

so n_A / n_total = mole fraction of gas A in mixture