Question

How do I perform a titration on coca-cola or Pepsi, when I cannot see the color change because the color is too dark. The indicator is phenolphthalein.

Answer 1

For dark reactants, use a pH meter.
For colorless WEAK reactants(acids/bases), use phenolpthalein..
For colorless STRONG reactants, use methyl orange.

Answer 2

Answer: maybe you need to do very dilute solution?

Explanation: you should have an pH meter instead of indicator.

Phosphoric acid H3PO4 have three ekvivalent points.

Another way could be using a conductivity meter.