In a strong acid strong base titration at room temperature

In a strong acid - strong base titration at room temperature, the pH at the equivalence point is 7. The indicator bromophenol blue changes colour over the pH range of 3.0 - 4.6. Explain why it is okay to use the indicator for this titration.

Solution

Yes,It is okay to use the indicator bromophenol blue because the reaction between an antacid tabletsand HCl is not a strong acid-strong base titration but a strong acid-weak base titration. In a strongacid-weak base titration, the equivalence point is not 7, but it is in the range of 3.0-4.6. This isdue to the fact that that acid produces much more H30+ions than the weak base produces OH-. Asa result, there is a higher concentration of H30+ions at the equivalence point which results in amore acidic pH range of 3.0-4.6.