acid", and "conjugate base" are not fixed for a certain chemical species but are interchangeable according to the reaction taking place. Strength of conjugates The strength of a conjugate acid is directly proportional to its dissociation constant. If a conjugate acid is strong, its dissociation will have a higher equilibrium constant and the products of the reaction will be favored. The strength of a conjugate base can be seen as the tendency of the species to "pull" hydrogen protons towards itself. If a conjugate base is classified as strong, it will "hold on" to the hydrogen proton when in solution and its acid will not dissociate. If a species is classified as a strong acid, its conjugate base will be weak. An example of this case would be the dissociation of hydrochloric acid in water. Since HCl is a strong acid (it dissociates to a great extent), its conjugate base () will be a weak conjugate base. Therefore, in this system, most will be in the form of a hydronium ion instead of attached to a Cl− anion and the conjugate base will be weaker than a water molecule. On the other hand, if a species is classified as a weak acid its conjugate base will not necessarily be a strong base. Consider that acetate, the conjugate base of acetic acid, has a base dissociation constant (Kb) of approximately , making it a weak base. In order for a species to have a strong conjugate base it has to be a very weak acid, like water for example. Identifying conjugate acid–base pairs To identify the conjugate acid, look for the pair of compounds that are related. The acid–base reaction can be viewed in a before and after sense. The before is the reactant side of the equation, the after is the product side of the equation. The conjugate acid in the after side of an equation gains a hydrogen ion, so in the before side of the equation the compound that has one less hydrogen ion of the conjugate acid is the base. The conjugate base in the after side of the equation lost a hydrogen ion, so in the before side of the equation, the compound that has one more hydrogen ion of the conjugate base is the acid. Consider the following acid–base reaction: Nitric acid () is an acid because it donates a proton to the water molecule