A0.001 molar solution of weak acid has a ph = 4.0. what is the pka of the acid?
a. 4
b. 5
c. 6
d. 7
e. 8

A 0.001 molar solution of weak acid has a pH = 4.0,The pKa is :

B. 5

Explanation:

pH = It is negative logarithm of hydrogen ion concentration.

pH = -log([H+])

Ka = It is the dissociation constant.

pKa = -log(Ka)

The acid dissociates according to the equation given below:

Here , The concentration of A- and H+ will be same

So,

[H+] = [A-].....(1)

Now ,

pH = 4.0

pH = -log([H+])

4.0 = -log([H+])

- 4.0 = log([H+])        take antilog both side::"use scientific calculator"

From equation (1), [A-] =

[HA] = 0.001 M (given)

Insert the value of HA , H+ and A- in Ka

pKa = -log(Ka)

pKa = 5

< > according to newton's third law of motion, forces always act in equal but opposite pairs. another way of saying this is for every action, there is an equal but opposite reaction.< >

2b2t

explanation:

2b2t