Chapter 6, Problem 6E.17E

Interpretation Introduction

Interpretation:

The molar concentrations of all phosphate species in $H_{3}P{O}_4\left(aq\right)$ at $pH$ of $2.25$ have to be calculated.

Concept Introduction:

Fractions of species in a solution of triprotic acid $\left(H_{3}A\right)$ can be calculated as given below.

  $\begin{array}{l}f\left(H_{3}A\right)=\frac{{\left[H_3{O}^{+}\right]}^3}{H}\\ \\ f\left(H_2{A}^{-}\right)=\frac{{\left[H_3{O}^{+}\right]}^2{K}_{a1}}{H}\\ \\ f\left(H{A}^{2-}\right)=\frac{\left[H_3{O}^{+}\right]K_{a1}{K}_{a2}}{H}\\ \\ f\left(A^{3-}\right)=\frac{K_{a1}{K}_{a2}{K}_{a3}}{H}\\ \\ Where,H={\left[H_3{O}^{+}\right]}^3+{\left[H_3{O}^{+}\right]}^2{K}_{a1}+\left[H_3{O}^{+}\right]K_{a1}{K}_{a2}+K_{a1}{K}_{a2}{K}_{a3}\end{array}$