20 mL of an approximately 10% aqueous solution of
ethylamine, CH3CH2NH2, is titrated with 0.3000 M
aqueous HCl. Which indicator would be most suitable
for this titration? The pKa of CH3CH2NH3
+ is 10.75.

(A) Thymol blue, color change from pH = 1.2 to 2.8
(B) Bromocresol green, color change from pH = 4.0 to
5.6
(C) Phenolphthalein, color change from pH = 8.0 to 10.0
(D) Alizarin yellow R, color change from pH = 10.0 to
12.0