Question

How many grams of dipotassium succinate trihydrate (K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 710.0 mL of a 0.0485 M succinic acid solution to produce a pH of 5.844? Succinic acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2).

Answer 1

pH ofacidic buffer = pka + log(salT/succinicacid)

     5.844 = 5.636 +log(x/(710*0.0485/1000))

X = Salt = no of mole of K2C4H4O4·3H2O = 0.0556 mol

Amount of K2C4H4O4·3H2O = n*Mwt

                         = 0.0556*248.32

                         = 13.8 g