Respuesta :
Ka of lactic acid is 8.24 x 10⁻⁴
Explanation:
Given-
[Ca²⁺] = 0.26M
pH = 8.4
Salt is 100% dissociated
Ka = ?
Ca(Lact)₂ = Ca²⁺ + 2 Lact-
[lact⁻ ] = 0.26 x 2
= 0.52 M
pOH = 14 - 8.40
= 5.60
[OH⁻] = 10⁻ X 60 = 2.51 x 10⁻⁶ M = [lact⁻]
Kb = Kw/Ka
= [tex]\frac{( 2.51 X 10^-^6)^2}{0.52} - 2.51 X 10^-^6[/tex]
= 1.21 x 10⁻¹¹
Ka = Kw/Kb
= [tex]\frac{1 X 10^-14}{1.21 X 10^-^1^1}[/tex]
= 8.24 x 10⁻⁴
Thus, Ka of lactic acid is 8.24 x 10⁻⁴
The Ka of lactic acid is 8.24 x 10⁻⁴
Calculation of ka of lactic acid:
Since
A saturated solution of this salt, which we can represent as (Ca(Lact)2) has a [Ca2+]=0.26M and a pH=8.40.
Now
We know that
Ca(Lact)₂ = Ca²⁺ + 2 Lact-
So,
[lact⁻ ] = 0.26 x 2
= 0.52 M
Now
pOH = 14 - 8.40
= 5.60
Now
[OH⁻] = 10⁻ X 60 = 2.51 x 10⁻⁶ M = [lact⁻]
Now
kb = kw/ka
= (2.51*10^-6)^2/0.52*2*.51*10^-6
= 1.21 x 10⁻¹¹
Now Ka is
= 1*10^-14/1.21*10^-11
= 8.24 x 10⁻⁴
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