# Problem: Propionic acid, C2H5CO2H (Ka = 1.34 × 10−5), is used in the manufacture of calcium propionate, a food preservative. What is the hydronium ion concentration in a 0.698-M solution of C2H5CO2H?

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###### FREE Expert Solution

Dissociation: C2H5CO2H (aq) + H2O(l)  H3O+(aq) + C2H5CO2- (aq)

ICE CHART:

Ka expression:

$\overline{){{\mathbf{K}}}_{{\mathbf{a}}}{\mathbf{=}}\frac{\mathbf{products}}{\mathbf{reactants}}{\mathbf{=}}\frac{\mathbf{\left[}{\mathbf{H}}_{\mathbf{3}}{\mathbf{O}}^{\mathbf{+}}\mathbf{\right]}\mathbf{\left[}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}{{\mathbf{CO}}_{\mathbf{2}}}^{\mathbf{-}}\mathbf{\right]}}{\mathbf{\left[}{\mathbf{C}}_{\mathbf{2}}{\mathbf{H}}_{\mathbf{5}}{\mathbf{CO}}_{\mathbf{2}}\mathbf{H}\mathbf{\right]}}}$

###### Problem Details

Propionic acid, C2H5CO2H (Ka = 1.34 × 10−5), is used in the manufacture of calcium propionate, a food preservative. What is the hydronium ion concentration in a 0.698-M solution of C2H5CO2H?