Equilibrium constant Kp for homogeneous systems. Gaseous equilibria also follow the equilibrium law.  It is usual to express their concentrations in a different way using the idea of partial pressure.

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Partial pressure

In a mixture of gases, each gas contributes to the total pressure.  This contribution is called its partial pressure, p. The partial pressure is the pressure that the gas would exert, if it occupied a container of its own. 

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The sum of all the partial pressures is equal to the total pressure.

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Partial pressure = mole fraction of gas x total pressure

 

Mole fraction

Is the mole fraction of a particular gas taken from the total number of moles of gas

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