gaseous state Flashcards

1
Q

state avogadros law and formula

A

for a gas at constant temperature and pressure,
v1/n1 = v2/n2

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2
Q

state gay-lussacs law and formula

A

for a fixed mass of gas at constant volume, the
p1/t1=p2/t2

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3
Q

state charles law and formula

A

at constant pressure and fixed mass, v1/t1 = v2/t2

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4
Q

boyles law and formula

A

for a fixed mass of gas at constant temperature
p1v1 = p2v2

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5
Q

explain ideal gas equation

A

pV = nRT
p in Pa or Nm-2
V in m3
n in mol
T in Kelvin

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6
Q

using ideal gas eqn to determine molar mass

A

M = mRT/pV
M in g mol-1
m in g

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7
Q

using ideal gas eqn to determine density of a gas

A

density = m/v = pM/RT

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8
Q

assumptions of ideal gas

A
  1. gas particles have negligible volume
  2. gas particles exert negligible attractive forces on one another
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9
Q

how does a gas approach ideality at low pressure and high temperature

A

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

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10
Q

how does a gas deviate from ideality

A

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

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11
Q

why is there negative deviation when moderately high pressure is exerted on the system

A

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

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12
Q

why is there positive deviation when very high pressure is exerted on the system

A

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

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13
Q

ranking of extent of deviation

A

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

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14
Q

mole fraction

A

mole fraction = Xa = no of moles of a/total no of moles

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15
Q

partial pressure

A

P of a = Xa times Ptotal

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16
Q

what is evaporation

A

in a closed container,
some of the more energetic particles on hte surface of the liquid possess enough energy to escape from the attractive forces holding the liquid togther, evaporating

17
Q

vapour pressure

A

pressure exerted on the liquid surface and on the wall of the container by the gaseous particles that have evaporated and are trapped above the liquid

18
Q

saturated vapour pressure

A

at a certain temperature, number of particles evaporating = number of particles condensing so there is a fixed number of gaseous particles in the space above the liquid which exerts a vapour pressure, namely saturated vapour pressure

19
Q

relating intermolecular forces, boiling points and vapour pressures

A

stronger the intermolecular forces of a liquid, more difficult for its particles to escape from liquid surface so lower its volatility and saturated vapour pressure, but higher its boiling point