Assuming complete dissociation, what is the pH of a 3.11 mg/L Ba(OH)2 solution?

pH = 9.56

Explanation:

Let's assume we have 1 liter of the solution. Then we would have 3.11 mg of Ba(OH)₂.

We convert 3.11 mg of Ba(OH)₂ into moles, using its molar mass:

There are two OH⁻ moles per Ba(OH)₂ mol. Meaning there's (2*1.82x10⁻⁵) 3.63x10⁻⁵ moles of OH⁻.

As the volume is 1 L, the molar concentration of OH⁻, [OH⁻] is 3.63x10⁻⁵ M.

With the above information in mind we calculate the pOH of the solution:

Finally we calculate the pH:

a electronegativity decreases beacuse the size of nucleus is bigger.