A solution of benzoic acid (c6h5cooh) that is 0.20m has a ph of 2.45. What is ka for benzoic acid how to find out the value of ka for benzoic acid?

Helo, reders welcome to “** textilesgreen.in**” today we will discuss about how to calculate the value of ka for benzoic acid.

lets get started;

## A Solution of benzoic acid (c6h5cooh) that is 0.20m has a ph of 2.45. What is ka for benzoic acid

First you find out the value of **H+ ions**, it is also called hydrogen ion but how to find the value of H+ ions.

How do you find the value of** H+ ion**?

the hydrogen ions (H+ ions) concentration in a solution, [H+] in mole L.

- It is easy to calculate if the pH of solution is known. If you have value of pH of solution then you can find the H+ ion.
- ph is define as negative logrthims of hydrogen ions in mole L. For example

pH = – log10[H+]

3. H+ in mole L -1 is calculated using the formula

[H+] = 10 – pH

Here in this case first off all find the value of [H+] ions, and the value of pH of solution are given,

{pH = 2.45}

pH = -log10[H+]

2.45 = -log10[H+]

[H+] = 3.55 × 10^-3

Now, we can use the initial concentration and the H+ ion concentration for find out the value of ka.

C6H5COOH = C6H5COOH – + H+

0.20 0 0

-x x x

0.20 -x x x

x = [H+] = 3.55 × 10^-3

[C6H5COOH-] = 3.55 ×10^-3

[C6H5COOH] = 0.1965

Now,

Ka = 3.55 × 10^-3 (3.55 × 10^-3)/ 0.1965

**ka = 6.42 × 10^-5**

### What is ph = -log [H+]?

this equation is used find the value of H+ ions,

ph = -log[H+]

where, [H+] is hydrogen ion concentration

we are required to take common base 10 hydrogen ions concentration. If you take the base 10. this way you can find the value of pH.

For example,

ph = -log10[H+]

these are the equation, in order to calculate the value of pH.