Question

A 1.25 × 10-4 m solution of the anti-inflammatory drug naproxen has a ph = 4.2. the ka and pka of naproxen are ________ and ________.

Answer 1

Naproxen is known to be a weak acid. In order to calculate its ka and pka, use the equation of getting the ph of weak acid which is ph= -1/2 log [(Ka)(Mwa)]. The Ka value is 3.18x10^-5. The pKa can be obtained through pKa = - log Ka. The pKa is 4.5.

Answer 2

`Ka=6.43x10^(-5)`

`pKa=4.19`

Step-by-step explanation:

Hello,

In this case, the pH provides the concentration of hydrogen in its dissociation:

`Naproxen\rightleftharpoons H^++Naproxen^-`

Thus, such concentration is:

`[H^+]=10^(-4.2)=6.31x10^(-5)M`

Thus, the Ka, by means of the dissociation law of mass action:

`Ka=((6.31x10^(-5))^2)/(1.25x10^(-4)-6.31x10^(-5))=6.43x10^(-5)`

Hence the pKa is:

`pKa=-log(Ka)=-log(6.43x10^(-5))=4.19`

Best regards.