**Video** **Tutorial** Equilibrium Constant, K_{p}

**Quick** **Notes** Equilibrium Constant, K_{p}

- The equilibrium constant, Kp, describes the ratio of reactants compared to products at equilibrium for a gaseous equilibrium system.
- K
_{p}is found by dividing the partial pressures of all products by the partial pressures of all reactants (raised to the power of their molar ratios).

- K
- The partial pressures of a gas in a closed system are directly linked to the moles of that gas.
- Partial pressures of reactants and products can be used to determine how much the forward or reverse reaction is favoured.

**Full** **Notes** Equilibrium Constant, K_{p}

The equilibrium constant, K_{c}, is a constant used to describe how much the forward or backward reaction is favoured in an equilibrium system. See Equilibrium Constant, K_{c}.

The equilibrium constant, K_{p}, works in the same way as K_{c}. The key difference is that K_{c} uses molar concentrations (mol dm^{-3}), whereas K_{p} uses partial pressures.

For the following reaction:

By taking known moles of gases and the total pressure of a system, K_{p} can be found for a particular reversible reaction. For how to find mole fractions and partial pressures, see Mole Fractions and Partial Pressures.

Be aware when using K_{p} expressions to check units! K_{p} can have different units for different systems, also make sure to check that units used for pressure are constant (Pa and kPa).