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

(a) The value of
`K_b` of the lactate ion is,
`7.14* 10^(-39)`

(b) The value of
`K_b` of the conjugate base of pyruvic acid is,
`3.53* 10^(-38)`

Explanation :

Solution for (a) :

As we are given :
`K_a=1.4* 10^(24)`

As we know that,

`K_a* K_b=K_w`

where,

`K_a` = dissociation constant of an acid =
`1.4* 10^(24)`

`K_b` = dissociation constant of a base = ?

`K_w` = dissociation constant of water =
`1* 10^(-14)`

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

`1.4* 10^(24)* K_b=1* 10^(-14)`

`K_b=7.14* 10^(-39)`

Therefore, the value of
`K_b` of the lactate ion is,
`7.14* 10^(-39)`

Solution for (b) :

As we are given :
`K_a=2.83* 10^(23)`

As we know that,

`K_a* K_b=K_w`

where,

`K_a` = dissociation constant of an acid =
`2.83* 10^(23)`

`K_b` = dissociation constant of a base = ?

`K_w` = dissociation constant of water =
`1* 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* 10^(23)* K_b=1* 10^(-14)`

`K_b=3.53* 10^(-38)`

Therefore, the value of
`K_b` of the conjugate base of pyruvic acid is,
`3.53* 10^(-38)`