Question

Calculate the indicated value based on the information given: a. What is the Kb of the lactate ion? The Ka of lactic acid is 1.4 3 1024 . b. What is the Kb of the conjugate base of pyruvic acid? The Ka of pyruvic acid is 2.8 3 1023 .

Answer 1

Answer :

(a) The value of $K_b$ of the lactate ion is, $7.14\times 10^{-39}$

(b) The value of $K_b$ of the conjugate base of pyruvic acid is, $3.53\times 10^{-38}$

Explanation :

Solution for (a) :

As we are given : $K_a=1.4\times 10^{24}$

As we know that,

$K_a\times K_b=K_w$

where,

$K_a$ = dissociation constant of an acid = $1.4\times 10^{24}$

$K_b$ = dissociation constant of a base = ?

$K_w$ = dissociation constant of water = $1\times 10^{-14}$

Now put all the given values in the above expression, we get the dissociation constant of a base (lactate ion).

$1.4\times 10^{24}\times K_b=1\times 10^{-14}$

$K_b=7.14\times 10^{-39}$

Therefore, the value of $K_b$ of the lactate ion is, $7.14\times 10^{-39}$

Solution for (b) :

As we are given : $K_a=2.83\times 10^{23}$

As we know that,

$K_a\times K_b=K_w$

where,

$K_a$ = dissociation constant of an acid = $2.83\times 10^{23}$

$K_b$ = dissociation constant of a base = ?

$K_w$ = dissociation constant of water = $1\times 10^{-14}$

Now put all the given values in the above expression, we get the dissociation constant of a base (conjugate base of pyruvic acid).

$2.83\times 10^{23}\times K_b=1\times 10^{-14}$

$K_b=3.53\times 10^{-38}$

Therefore, the value of $K_b$ of the conjugate base of pyruvic acid is, $3.53\times 10^{-38}$