Question

The pka of hf is 3.2 determine the pkb of hf?

Answer 1

Well, first we must remember that

$pK_{a}+pK_{b}=14$

This is because

$K_{a}*K_{b}=10^{-14}$

$-log(K_{a}*K_{b})=-log(10^{-14})\\-logK_{a}+-logK_{b}=-log(10^{-14})\\pK_{a}+pK_{b}=14$

So then

$pK_{b}=14-pK_{a}=14-3.2=1.8$

Answer 2

Answer : The value of $pK_b$ is, 10.8

Explanation :

First we have to calculate the value of $K_a$.

The expression used for the calculation of $pK_a$ is:

$pK_a=-\log (K_a)$

Now put the value of $pK_a$ in this expression, we get:

$3.2=-\log (K_a)$

$K_a=6.3\times 10^{-4}$

Now we have to calculate the value of $K_b$.

Formula used :

$K_a\times K_b=K_w$

$K_b=\frac{K_w}{K_a}$

Now put the value of $K_a$ in this expression, we get:

$K_b=\frac{1\times 10^{-14}}{6.3\times 10^{-4}}$

$K_b=1.5\times 10^{-11}$

Now we have to calculate the value of $pK_b$.

The expression used for the calculation of $pK_b$ is:

$pK_b=-\log (K_b)$

Now put the value of $K_b$ in this expression, we get:

$pK_b=-\log (1.5\times 10^{-11})$

$pK_b=10.8$

Therefore, the value of $pK_b$ is, 10.8