Benzoic acid, HC6H5CO2,is a monoprotic acid(only one H+ ionizes)with a Ka=6.5×10^-5. Calculate [H+] and the pH of a .32M solution of benzoic acid. PLEASE ANSWER. ​

[H⁺] = 4.56x10⁻³ M

pH = 2.34

Explanation:

Hello there!

In this case, according to the ionization reaction of benzoic acid:

Whereas , we can set up the equilibrium expression in terms of (reaction extent) to obtain:

However, since Ka<<<1, we can neglect the on bottom to easily solve for it:

Which is actually the same as [H⁺]. Finally, the pH turns out to be:

Best regards!