# What are the meanings of a strong acid and a weak acid? What are examples of each?

Apr 10, 2017

The strength of an acid, $H A$, depends on the extent of dissociation in water..........

#### Explanation:

That is, we assess the position of the following equilibrium:

$H A \left(a q\right) + {H}_{2} O \left(l\right) r i g h t \le f t h a r p \infty n s {H}_{3} {O}^{+} + {A}^{-}$

For STRONG ACIDS, the equilibrium lies almost quantitatively to the right, and ionization may be regarded as complete. For weak acids, the equilibrium lies to somewhat to the left, so that at equilibrium, some quantity of $H A$ remains in solution.

Examples of strong acids include $H X$ (X=Cl, Br, I; X!=F), ${H}_{2} S {O}_{4}$, $H C l {O}_{4}$, and (a bit weaker) $H N {O}_{3}$. Aqueous solutions of these acids may be regarded as stoichiometric in ${H}_{3} {O}^{+}$, except for sulfuric acid, which contributes two hydronium ions to solution (of course $H S {O}_{4}^{-}$ is NOT as strong an acid as its parent acid):

${H}_{2} S {O}_{4} + 2 {H}_{2} O r i g h t \le f t h a r p \infty n s 2 {H}_{3} {O}^{+} + S {O}_{4}^{2 -}$

Examples of weak acids include $H F$, ${H}_{3} P {O}_{4}$, and $N {H}_{4}^{+}$. There will a lot more discussion, and a lot more examples in your text. Don't forget to consult it!