Why is it possible to have a concentrated weak acid?

May 18, 2017

Because $\text{concentration}$ refers to the amount of solute present in a given volume of $\text{solution..........}$

Explanation:

$\text{Acetic acid}$, $\text{H"_3"CCO"_2"H}$, CERTAINLY behaves as a weak acid in water, i.e. the following equilibrium lies to the left as we face the page:

${\text{H"_3"CCO"_2"H" +"H"_2"O"rightleftharpoons"H"_3"CCO"_2^(-) +"H"_3"O}}^{+}$

This equilibrium may be carefully measured, and......................

${K}_{a} = \left(\left[\text{H"_3"CCO"_2^(-)]["H"_3"O"^+])/(["H"_3"CCO"_2"H}\right]\right) = {10}^{- 4.76}$

Glacial acetic acid (i.e. very pure acetic acid), has a concentration of $15.5 \cdot m o l \cdot {L}^{-} 1$; of course the description of acidity requires dissolution in water.............