Question

Problem:Iodic acid (${\mathbf{HIO}}_{\mathbf{3}}$) is fairly strong for a weak acid, having a Ka equal to 0.16 at 25°C. Compute the pH of a 0.100 M solution of ${\mathbf{HIO}}_{\mathbf{3}}$.

Short answer

The pH of the Iodic solution is 3.79.

Step-by-step solution

Given data

The molarity of theiodic acidis 0.100 M.

The temperature is ${\text{25}}^{\text{o}}\text{C}$.

The Ka of the iodic acid is 0.16.

Chemical reaction

The chemical reaction when the iodic acid is dissolved in water that results in the formation of the iodic acid solution is written as follows:

${\mathrm{HIO}}_3+{\mathrm{H}}_2\mathrm{O}\to {\mathrm{IO}}_3+{\mathrm{H}}_3{\mathrm{O}}^{+}$

calculating the pH

The pH of the iodic acid is calculated using the formula as follows:

$\begin{array}{rcl}pH& =& -log\sqrt{\left[{\mathrm{HIO}}_3\right]\times {\mathrm{K}}_{\mathrm{a}}}\\ & & \text{=}\text{log}\sqrt{\left[\text{0.001}\right]\text{×0.16}}\\ & & \text{=}\text{3.79}\end{array}$

Therefore, the pH of the given iodic acid solution is 3.79.