A is a solution of HNO3 of unknown concentration. B is a standard solution of Naoh 25cm3 portion of solution B required an average of 24.00cm3 of solution A for complete neutralization.
(1) suggests with reason a suitable indicator for
the reaction
An indicator that changes color at pH = 7. Look in your text for a list of indicators with pH color change. I'm sure you can find a table on google.
Bromothymol Blue
To suggest a suitable indicator for the reaction between the unknown concentration of HNO3 (solution A) and the standard solution of NaOH (solution B), we need to consider the pH range at which the reaction occurs.
In this case, since we are neutralizing an acid (HNO3) with a base (NaOH), the reaction will occur at the equivalence point, where the moles of acid are equal to the moles of base. This point will correspond to a neutral pH.
A suitable indicator for a neutralization reaction is one that undergoes a color change at or near a neutral pH. One commonly used indicator is phenolphthalein. Phenolphthalein is colorless in acidic solutions and turns pink or red in alkaline (basic) solutions. It transitions from colorless to pink within a pH range of approximately 8.2 to 10.
Therefore, phenolphthalein would be a suitable indicator for this reaction between the unknown concentration of HNO3 and the standard solution of NaOH.