In: Chemistry
What is the pH of 1.000 L of a solution of 100.0 g of glutamic
acid (C5H9NO4, a diprotic acid; K1 = 8.5 ×
10−5, K2 = 3.39 × 10−10) to which has been added 20.0 g of NaOH
during the preparation of monosodium
glutamate, the flavoring agent? What is the pH when exactly 1 mol
of NaOH per mole of acid has been added?
no of moles = W/G.M.Wt
= 100/147*1 = 0.68 M
no of moles of NaOH = W/G.M.Wt = 20/40 = 0.5 moles
C5H9NO4 + NaOH --------> NaC5H8NO4 + H2O
I 0.68 0.5 0
C -0.5 -0.5 0.5
E 0.18 0 0.5
Pka = -logKa
= -log8.5*10-5
= 4.0705
PH = Pka + log[NaC5H8NO4]/[C5H9NO4]
= 4.0705 + log0.5/0.18
= 4.0705 + 0.4436
= 4.5141