Phenolphthalein is preferred over bromothymol blue for determining the equivalence point in titrations involving strong acids and bases due to its clearer color change. Bromothymol blue has a transition range of pH 6.0 to 7.6, which can lead to ambiguous results at pH 7, as it may not provide a distinct endpoint. In contrast, phenolphthalein, with a transition range of pH 8.3 to 10.0, offers a more definitive color change from colorless to pink, allowing for more consistent results. The discussion emphasizes the importance of selecting an indicator whose transition range encompasses the equivalence point for accurate titration results.
PREREQUISITESChemistry students, laboratory technicians, educators, and anyone involved in analytical chemistry or titration experiments.
Actually, that is not quite right. The best indicator to use for a titration is one which the equivalence point (pH) falls into the range - preferably the middle - of the indicator. In this case, the bromothymol blue would be ideal, because it would change colour when the pH equals about 7. The phenolphthalein won't even start to change colours.zwtipp05 said:My guess would be that since 7 falls inside the range for the blue you would have to stop the titration while the color is still mixed. With phenolphthalein you stop when it completely changes color which makes it easier to obtain consistent results rather then trying to interpret the mix of colors.