Page 69 - Analytical Chemistry I E-book

Titration curve for H3PO4 with NaOH

• EP1 can be determined using
methyl orange as indicator.
H3PO4 + OH– → H2PO4– + H2O

• EP2 can be determined using
phenolphthalein as indicator.
H3PO4 + 2OH– → HPO42– + 2H2O

• If 2 separate portions of H3PO4
sample were analyzed,
EP2 = 2 x EP1