What did you observe/what do you suspect will happen. Suppose we have an indicator, an organic substance that changes color at certain pH. Let's say we're using Phenolphthalein, which undergoes a color change from clear to pink at pH around 8.2. Just like in lab, if we add a couple drops of the indicator to a flask of pure water, what happens when 1-2 drops of 0.1M NaOH is now added to that flask of water (with regards to color)?

Question

What did you observe/what do you suspect will happen. Suppose we have an indicator, an organic substance that changes color at certain pH. Let's say we're using Phenolphthalein, which undergoes a color change from clear to pink at pH around 8.2. Just like in lab, if we add a couple drops of the indicator to a flask of pure water, what happens when 1-2 drops of 0.1M NaOH is now added to that flask of water (with regards to color)?

a) The water remains clear

b) The water turns blue

c) The water turns pink

d) The water bubbles

Group of answer choices

c)

a)

b)

d)

Answer 1

c) The water turns pink

Since Phenolphthalein changes color to pink at a pH around 8.2, when NaOH, a strong base, is added to the water, it will increase the pH of the solution and cause the Phenolphthalein to change to its pink color.