Question

What is the pH of a 1.9 M solution of HClO4?

Answer 1

Answer : The pH of the solution is, -0.279

Explanation :

The balanced chemical reaction will be:

`HClO_4\rightleftharpoons H^++ClO_4^-`

As, 1 mole of
`HClO_4` dissociated in solution to give 1 mole of
`H^+` ion and 1 mole of
`ClO_4^-` ion

So, 1.9 M of
`HClO_4` dissociated in solution to give 1.9 M of
`H^+` ion and 1.9 M of
`ClO_4^-` ion

Now we have to calculate the pH of the solution.

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

`pH=-\log (1.9)`

`pH=-0.279`

As we know that the strong acid with concentration greater than 1 M will have the negative pH.

Therefore, the pH of the solution is, -0.279

Answer 2

The compound HClO4 is said to be a strong acid which means it completely dissociates into the solution forming ions of hydrogen and perchlorate ion.

HClO4 = H+ + ClO4-

pH = -log [H+]
pH = - log [1.9]
pH = -0.28