Chapter 6, Problem 6F.2AST

Interpretation Introduction

Interpretation:

The $pHof2.0\times {10}^{-4}MHCN\left(aq\right)$ has to be calculated.

Concept Introduction:

The contribution of autoprotolysis of water to the calculation of $pH$ of very dilute solutions of weak acid must be taken into consideration if the hydronium ion concentration is less than ${10}^{-6}M.$

For very dilute solutions of weak acid, the given below equation should be used.

  ${\left[H_3{O}^{+}\right]}^3+K_a{\left[H_3{O}^{+}\right]}^2-\left(K_W+K_a{\left[HA\right]}_{Initial}\right)\left[H_3{O}^{+}\right]-K_a{K}_W=0$