Question

27.3 mL sample of a 0.488 M aqueous hydrofluoric acid solution is titrated with a 0.367 M aqueous potassium hydroxide solution. What is the pH at the start of the titration, before any potassium hydroxide has been added?

Answer 1

Answer: The pH of the solution when no base is added is 0.311

Explanation:

The chemical formula of hydrofluroic acid is HF. It is a monobasic acid.

1 mole of HF produces 1 mole of hydrogen ions and 1 mole of fluoride ions.

To calculate the pH of the solution when no base is added, we use the equation:

$pH=-\log[H^+]$

We are given:

$[H^+]=0.488M$

Putting values in above equation, we get:

$pH=-\log(0.448)\\\\pH=0.311$

Hence, the pH of the solution when no base is added is 0.311