Calculate the pH of 0.100 molar solution of sodium chloroacetate. Ka for chloroacetic acid = 1.4 x 10^-3
Calculate the pH of 0.100 molar solution of sodium chloroacetate.
Ka for chloroacetic acid = 1.4 x 10^-3
ClCH2COONa (B) + H2O ClCH2COOH (A) + OH-
Conjugate Base Week Acid
Sodium acetate is a weak base and acetic acid is a weak acid,
Therefore, we can write,
Ka(A)xKb(B) = Kw, or Kb=Kw/Ka = 10^-14/(1.4*10^-3) =7.14x10^-12 M
As the dissociation of this weak base will be very less, we can write,
cb >>> Kb, so we can use the following formula,
[OH-]^2 =Kb.cb = 7.14x10^-12x0.1
Or [OH-] = 8.45x10^-7
So, pOH = -log[OH-]= -log (8.45x10^-7) = 6.07
pH=14-pOH= 14-6.07 = 7.93
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