Question

For all of the following questions 20.00 mL of 0.200 M HBr is titrated with 0.200 M KOH.

Region 1: Initial pH: Before any titrant is added to our starting material
What is the concentration of H+ at this point in the titration?
M

What is the pH based on this H+ ion concentration?

Answer 1

The concentration of
`H^+` before any titrant added to our starting material is 0.200 M.

The pH based on this
`H^+` ion concentration is 0.698

Explanation :

First we have to calculate the concentration of
`H^+` before any titrant is added to our starting material.

As we are given:

Concentration of HBr = 0.200 M

As we know that the HBr is a strong acid that dissociates complete to give hydrogen ion
`H^+` and bromide ion
`Br^-`.

As, 1 M of HBr dissociates to give 1 M of
`H^+`

So, 0.200 M of HBr dissociates to give 0.200 M of
`H^+`

Thus, the concentration of
`H^+` before any titrant added to our starting material is 0.200 M.

Now we have to calculate the pH based on this
`H^+` ion concentration.

pH : It is defined as the negative logarithm of hydrogen ion concentration.

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

`pH=-\log (0.200)`

`pH=0.698`

Thus, the pH based on this
`H^+` ion concentration is 0.698