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ChemistryEdu Logo Gaseous State | Gas Laws#

Boyle's Law#

  • At constant temperature, the pressure of a fixed mass of a gas is inversely proportional to its volume.
\[P ∝ {1 \over V}\]
\[PV = constant\]

Boyle's Law Graph

Charle's Law#

  • At constant pressure, the volume of a fixed mass of a gas is directly proportional to its temperature.
\[V ∝ T\]
\[ {V \over T} = constant\]

where, T = Absolute Temperature (Kelvin scale)

Charle's Law Graph in Celsius scale

\[Slope, m = tan Θ = {V_0 \over 273.15} ≈ {V_0 \over 273}\]
\[∴ V = {V_0 \over 273}T + V_0\]

where, T is in celsius.

  • A new temperature scale was introduced known as Kelvin scale.

Charle's Law Graph in Kelvin scale

Gay Lussac's Law#

  • At constant volume, for a fixed mass of a gas, pressure is directly proportional to its temperature.
\[P ∝ T\]
\[ {T \over P} = constant \]

where, T = Absolute Temperature (Kelvin scale)

Gay Lussac's Law Graph

Note

Mean free path, \(λ ∝ {T \over P}\). If Gay Lussac's Law is valid or applicable, then mean free path is constant. We will discuss mean free path in detail later.

Avogadro's Hypothesis#

  • At constant temperature and pressure, volume occupied by a gas, V is directly proportional to its number of moles, n.

  • More accurately, if \({T \over P} = constant\), then:

\[V ∝ n\]

Avogadro's Hypothesis Graph