Okay so I observed an experiment that went like this. When a colorless solution was poured from one beaker to another, it turned pink, then with continued pouring, the solution became colorless again.
Basically the experiment goes like this:
The first plastic cup is charged with 250 mL of water, 1 mL of 1% w/v phenolphthalein solution, and
10 drops of 2 M sulfuric acid solution. The plastic second cup is charged with 15 drops of 2 M potassium hydroxide solution. Slowly pour the contents of the first cup into the second cup. At first, the pouring will result in a red color. With continued pouring, the acid will neutralize the base, and the red color will disappear.
I know that phenolphthalein turns pink in basic solutions and is colorless in acidic solutions.
That's why it was colorless in sulfuric acid at first.
But what I don't understand is how come the phenolphthalein turned pink when the contents of the first cup was poured into the second cup.
I thought that this reaction would occur:
2 KOH + H2SO4 → K2SO4 + H2O
So why would the phenolphthalein turn pink if K2SO4 was produced, and why did it turn colorless again in the end?
Thank you for any *delete me*