Which of the following indicators would be most suitable for the titration of 0.10 M (CH₃)₃N(aq)with 0.10 M HClO₄(aq)? For trimethyamine,pK_b = 4.19.

Question

Quizplus · Accepted Answer

Bromocresol green would be the most suitable indicator for the titration of 0.10 M (CH3)3N(aq) with 0.10 M HClO4(aq) because the pKa of trimethylamine is 9.75, which is higher than the pKa of bromocresol green (4.7). This means that trimethylamine will be protonated and present as (CH3)3NH+ during the titration, and bromocresol green will be able to detect the pH change around the equivalence point when all of the trimethylamine has been protonated. The other indicators listed have pKa values that are either too high or too low to be suitable for this titration.

Which of the Following Indicators Would Be Most Suitable for the Titration