1)
moles of ascorbic acid = 0.685 x 0.773 = 0.5295
H2C6H6O6 + 2 NaOHÂ Â -----------> Na2C6H6O6 + 2
H2O
moles of NaOH = 2 x moles of acid
                       Â
= 2 x 0.5295
                       Â
= 1.06
1.76 x V = 1.06
V = 0.602
volume of NaOH at 2nd equivalence point = 0.6017 L
here C6H6O62- remains.
[C6H6O62-] = 0.5295 / 0.685 + 0.602 = 0.4115 M
C6H6O2-Â Â + H2OÂ Â Â ------------>
HC6H6O6- +Â Â OH-
0.411Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â Â
0
0.411 -
x                                           Â
x               Â
x
Kb1 = x^2 / 0.411 - x
1.26 x 10^-10 = x^2 / 0.411 - x
x = 7.22 x 10^-6
[OH-] = 7.22 x 10^-6 M
pOH = 5.14
pH = 8.86
