KHPh is a shorthand for a common weak acid used in titrations, called potassium hydrogen phthalate, as you know. Phthalate is a common name for an organic anion -- and yes, it does really exist. The bottle you used has it's formula written on the side, and you could sum the atom's weights. Or a quick web look up of "potassium hydrogen phthalate" will give you the answer.
Phthalates are also a general class of organic chemicals used as plasticizers, now out of favor due to health complications, so a search for "phthalates" is going to drive you quietly crazy without helping your problem.