# How are acids and bases different? How do there pH values differ?

Sep 29, 2016

An acid causes an increase in the concentration of the characteristic cation of the solvent...........

#### Explanation:

An acid causes an increase in the concentration of the characteristic cation of the solvent...........And a base causes an increases in the concentration of the characteristic anion.

For water, which is by far the most common solvent, the characteristic cation is what we call the hydronium ion, represented as ${H}_{3} {O}^{+}$, quite probably a cluster of 3-4 water molecules with an extra proton attached, and the characteristic anion is the hydroxide ion, ""^(-)OH.

In water under standard conditions at $298 \cdot K$, the ion product, $\left[H {O}^{-}\right] \left[{H}_{3} {O}^{+}\right]$ $=$ ${10}^{- 14}$.

Because, by definition, $p H$ $=$ $- {\log}_{10} \left[{H}_{3} {O}^{+}\right]$, addition of an acid will decrease the $p H$ of the solution. From the above, $p H + p O H = 14$ always.