Applications Involving the Equilibrium Constant

Knowing the value of the equilibrium constant for a reaction helps us do many thing.  The size of K tells us the inherent tendency of the reaction.  When K is much larger than 1, at equilibrium the reaction system will be mostly products.  

                                                                                                             A(g)--->B(g)
                                                                                                                
                                                                                                                 K= [B]
                                                                                                                        [A]

                                If K for this reaction equals 10,000 then the reaction strongly favors the products.
                                If K is much smaller than 1, this means that the reaction strongly favors the reactants.
                                If the equilibrium position is far to the left, the given reaction does not occur to a significant amount.

                                The equilibrium constant can also be used to calculate the concentrations of reactants and products.
                                If we know the value of K and all the concentrations but one, we can calculate the missing concentration.