# What are the characteristics of a weak acid?

Jan 30, 2017

Consider the equilibrium: $H A + {H}_{2} O r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + {A}^{-}$

#### Explanation:

The strength of the acid, $H A$, depends SOLELY on the extent this equilibrium lies to the right.

Strong acids, $H X \left(X \ne F\right) , H N {O}_{3} , {H}_{2} S {O}_{4} , H C l {O}_{4}$, undergo almost complete ionization, and $1 \cdot m o l \cdot {L}^{-} 1$ solution of such acid is stoichiometric in ${H}_{3} {O}^{+}$ and ${X}^{-}$ (what does $\text{stoichiometric}$ mean in this context)?

On the other hands, for weaker acids such as $\text{acetic acid", "phosphoric acid", "carbonic acid}$, the equilibrium lies towards the reactants as written, and at equilibrium significant concentrations of $H X$ obtain. This is a very important definition, so please try to get it right.

So to finally answer your question: the conjugate base of a weak acid competes strongly for the proton, and at equilibrium, appreciable concentrations of $H A$ obtain.

$\text{Claro?}$