Gas Laws
Summary
- The basic gas laws for a constant amount of matter…
- pressure-volume (constant temperature)
- The pressure of a gas is inversely proportional to its volume when temperature is constant.
- The product of pressure and volume is constant when temperature is constant.
- This relationship is known as Boyle's law or Mariotte's law.
- A constant temperature process is said to be isothermal.
P ∝ 1 (T constant) V P1V1 = P2V2 = constant
- volume-temperature (constant pressure)
- The volume of a gas is directly proportional to its temperature when pressure is constant.
- The ratio of volume to temperature is constant when pressure is constant.
- This relationship is known as Charles' law or Gay-Lussac's law.
- a constant pressure process is said to be isobaric.
V ∝ T (P constant)
V1 = V2 = constant T1 T2 - pressure-temperature (constant volume)
- The pressure of a gas is directly proportional to its temperature when volume is constant.
- The ratio of pressure to temperature is constant when volume is constant.
- This relationship is not associated with any particular scientist.
- A constant volume process is said to be isochoric.
P ∝ T (V constant)
P1 = P2 = constant T1 T2
- pressure-volume (constant temperature)
- Avogadro's hypothesis
- The number of molecules in a given volume of gas at a given temperature is the same for all gases.
- The ideal gas law (presented two ways)…
- functional thermodynamics
PV = nRT
where…P = absolute pressure T = absolute temperature V = volume n = number of moles R = gas constant = 8.314 J/mol K - statistical thermodynamics
PV = NkT
where…P = absolute pressure T = absolute temperature V = volume N = number of particles k = Boltzmann constant = 1.381 × 10−23J/K
- functional thermodynamics
- Thermodynamic changes with special names…
- An isobaric process is one that takes place without any change in pressure.
- An isochoric process is one that takes place without any change in volume.
- An isothermal process is one that takes place without any change in temperature.
- Isothermal processes are often described as "slow".
- The pressure of a gas is inversely proportional to its volume only if the change takes place isothermally.
- An adiabatic process is one that takes place without any exchange of heat.
- Adiabatic processes are often described as "fast".
- The pressure of a gas is not inversely proportional to its volume if the change takes place adiabatically.