no of mole of tris base = W/G.M.Wt
                                   Â
= 0.727/121 = 0.006moles
no of moles of HCl  = molarity* volume in L
                             Â
= 3*0.001727= 0.005181moles
               Â
tris base + HCl --------> tris salt
IÂ Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0.006Â Â Â Â Â Â Â
0.00518Â Â Â Â Â Â Â Â Â Â
0
CÂ Â Â Â Â Â Â Â Â Â Â
-0.00518Â Â Â Â
-0.00518Â Â Â Â Â Â Â Â
0.00518
EÂ Â Â Â Â Â Â Â Â Â Â Â Â
0.00082Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0.00518
    POH = pkb +log[tris salt]/[tris
base]
           Â
= 5.92 + log0.00518/0.00082
           Â
= 5.92 + 0.8 = 6.72
PHÂ Â Â = 14-POH
          =
14-6.72 = 7.28 >>answer
