Cresol red has two transition ranges listed in Table 11-3. What color would you expect it to be at the following pH values?

$$\begin{gathered} \left(a\right)\mathbf{}\mathbf{0} \\ \left(b\right)\mathbf{1} \\ \left(c\right)\mathbf{}\mathbf{6} \\ \left(d\right)\mathbf{9} \end{gathered}$$

The equivalence point ensures the titration reaction becomes completed and at this point, the number of moles of titrant and the number of moles of analyte remains equal. We cannot see the completion of the titration reaction - the titrant and the analyte becoming equal in stoichiometric proportion, hence we use a chemical compound called indicator called which indicates the end of the reaction by color change. The endpoint refers to the color change and indicates the equivalence point has been reached.

As we can see in the table 11-3 cresol red has two transition ranges.

The first one is between$\mathrm{pH}0.2$and 1.8. In that range it has an orange color. Before$\mathrm{pH}0.2$it has a red color and after$\mathrm{pH}1.8$it has a yellow color.The second one is between$\mathrm{pH}7.2$and 8.8. In that range it has an orange color. Before$\mathrm{pH}7.2$it has a yellow color and after$\mathrm{pH}8.8$it has a red color.

a) $\mathrm{pHO}$is prior to the first transition range and the color is going to be red.

b) $\mathrm{pH}1$is in in the first transition range and the color is going to be orange.

c) $\mathrm{pH}6$is prior to the second transition range and the color is going to be yellow.

d) $\mathrm{pH}9$is after the second transition range and the color is going to be red.