To which beaker should more 1.00M NaOH solution be added in order to change the color of the phenolphthalein indicator to pink?

Two beakers, 1 and 2, have 40.0mL of 1.50M HCl solution each and several drops of phenolphthalein indicator, which is colorless in acidic solutions but pink in basic. Then 20mL of distilled water has been added to beaker 2.

1 Answer
Apr 30, 2018

trick question - they will require the same amount of NaOH

Explanation:

The addition of water to beaker two would change its concentration & volume, but the number of moles HCl would be unaffected.
since each beaker would have equal moles of HCl in them, they would require the same volume of NaOH to neutralize and observe the color change.