Passage II
An acid-base titration involves slowly adding a measured amount of acid to a solution containing a base and an indicator. The indicator, a dye, signals the endpoint (exact point where the acid has consumed all of the base) by changing colors as the solution goes from basic to acidic. The pH scale is a relative measure of the strength of acids and bases (see Figure 1). Table 1 shows the amount of acid required to reach the endpoint of different basic solutions containing various natural indicators.
Figure adapted from J. Dudley Herron et al., Heath Chemistry. ©1987 by D.C. Heath and Company.
10. Strongly acidic or basic solutions have pH values near either end of the pH scale. According to the data in Table 1, which of the following indicators changes at the most acidic pH ?
Your Answer is
Correct Answer is H
Explanation
In table 1, when red cabbage is used as an indicator, the final pH reaches 4.0, which is the most acidic