gaseous state Flashcards
state avogadros law and formula
for a gas at constant temperature and pressure,
v1/n1 = v2/n2
state gay-lussacs law and formula
for a fixed mass of gas at constant volume, the
p1/t1=p2/t2
state charles law and formula
at constant pressure and fixed mass, v1/t1 = v2/t2
boyles law and formula
for a fixed mass of gas at constant temperature
p1v1 = p2v2
explain ideal gas equation
pV = nRT
p in Pa or Nm-2
V in m3
n in mol
T in Kelvin
using ideal gas eqn to determine molar mass
M = mRT/pV
M in g mol-1
m in g
using ideal gas eqn to determine density of a gas
density = m/v = pM/RT
assumptions of ideal gas
- gas particles have negligible volume
- gas particles exert negligible attractive forces on one another
how does a gas approach ideality at low pressure and high temperature
low pressure:
gas particles very far apart, volume occupied by gas particles negligible compared to volume of container
intramolecular attractive forces between widely spaced gas particles are negligible
high temperature:
gas particles possess high enough kinetic energy to overcome intermolecular attractive forces
intermolecular attractive forces can be considered negligible
how does a gas deviate from ideality
high pressure:
gas particles closer together, occupies smaller volume
vol of gas particles not negligible compared to vol of container
intermolecular attractive forces are significant
low temperature
gas particles posess less energy so intermolecular attractive forces are significant
why is there negative deviation when moderately high pressure is exerted on the system
volume of system becomes smaller
gas particles come closer together
intermolecular attractive forces between gas particles become significant
gas occupies smaller volume than ideally
pv/rt < 1
why is there positive deviation when very high pressure is exerted on the system
volume of the system becomes very small
gas particles very close together, repulsion between electron clouds present
gas particles experience intermolecular repulsive force
gas occupies volume larger than ideally
pv/rt > 1
ranking of extent of deviation
deviation is greatest for polar molecules for strong intermolecular forces of attraction such as pd-pd and H bonding, and smallest for small non-polar molecules
mole fraction
mole fraction = Xa = no of moles of a/total no of moles
partial pressure
P of a = Xa times Ptotal