Question

When phenolphthalein indicator is added to a colorless solution with a pH of 10, a student observes and concludes that the tested solution

1
remains colorless and is basic
2.
remains colorless and is acidic
3.
turns pink and is basic
4.
turns pink and is acidic

Answer 1

3. Turns Pink and is Basic

Step-by-step explanation:

Look at table M in your Chemistry Reference Table, you will see that 10 pH for phenolphthalein is color pink, and it's a base because the the pH is higher than 7 pH

Answer 2

3. turns pink and is basic

Step-by-step explanation:

Phenolphthalein is a pH indicator that remains colorless in acidic solutions, but in basic solutions it turns pink at a pH equal to 10.

Phenolphthalein is a weak acid that loses H+ cations in solution. The phenolphthalein molecule is colorless, while the phenolphthalein-derived anion is pink. When a base is added, phenolphthalein loses H+, forming the anion and causing it to turn pink. The color change cannot be explained only on the basis of deprotonation, a structural change occurs with the appearance of a ketoenolic tautomerism.