Question 146Steam Plants - 1st Asst/Chief

The correct answer is A) the sample color changes from pink to clear. The reasoning is that phenolphthalein is a pH indicator that turns pink in alkaline solutions. When titrating a boiler water sample with an acid solution, the sample's alkalinity is neutralized, causing the pink color to disappear as the pH drops below 8.2, the phenolphthalein endpoint. The other options are incorrect because B) reaching a pH of 10.5 is not the endpoint for alkalinity testing, C) chlorides are not being neutralized in this test, and D) the color change should be from pink to clear, not clear to pink.