AskiitianExpert Pramod-IIT-R
Last Activity: 14 Years ago
Dear Student MS. shefali,
HA == H+ + A-
c(1-a) ca ca
Ka = ca2/(1-a)
c= (1-a)/a2 * Ka...............(1)
H+ = ca
c = H+/a....................(2)
by equation 1 and 2
H+/a == (1-a)/a2 * Ka
H+ == (1-a)/a * Ka
H+/Ka == (1-a)/a
H+/Ka == (1/a)-1
(H+/Ka) +1 == (1/a)
[10(-pH)]/[10(-pKa)] + 1 == (1/a)
[10(pKa-pH) + 1] == (1/a)
a=1/[1+10(pKa-pH)]
So B option is correct.
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Pramod Kumar
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