If i dissolve 50.5 grams of calcium phosphate used to titrate an unknown which had a mass of 34.37 g...?

Question

what is the equivalent weight of the unknown? and can the molecular weight be determeined?

Answer 1

Your question is incomplete. With these amount of info you can't find either.

The equivalent weight is MW/a where a is the valency (for acid/ bases number of H+/OH- ,for redox reactions number of electrons gained/lost). If you don't know the value of a you cannot find the MW from the EW.

From the info you have you can find the EW (if you know the reaction for the titration).
Just as mole=mass/MW, greq= mass/EW.
In the titration you have greq Ca3(PO4)2= greq unknown
but greq Ca3(PO4)2= a1*mole1= a1*mass1/MW1
so

a1*mass1/MW1=mass2/EW2 =>

EW2=(mass2/mass1)*(MW1/a1)

MW1=310 (for Ca3(PO4)2)
mass1= 50.5 g of Ca3(PO4)2
mass2= 34.37 g unknown

a1=? You don't specify the reaction so we don't know how much is a1. If you just reach the first equivalence point (phosphate acting as a base) a1=1, if you reach the second a1=2 and if you reach the third a1=3. It could also be a precipitation titration...