19.1 The equilibrium constant Kc

The equilibrium constant Kc

The larger the value, the further the position of equilibrium towards the products.

Units of Kc

• substitute units into the expression for Kc

• cancel common units and show the final units on a single line.

• when writing put the positive indices before the negative indices.

Homogeneous and heterogeneous equilibria

Homogeneous

• contains equilibrium species that all have the same state or phase.

Heterogeneous

• contains equilibrium species that have different states or phases.

Kc only includes species that are (g) or (aq)

In homogeneous equilibria, the Kc expression contains concentration of all species.

However in heterogeneous equilibria, the concentration of solids and liquids are essentially constant, so any species that are solids and liquids are omitted from the Kc expression.

Calculating equilibrium quantities and calculating Kc

Question from experimental results