I hate buffers and pH
I have made an attempt at this question, please can someone validate my answer.
Calculate the pH of a 0.100 mol dm
-3 solution of propanoic acid, for which K
a=1.3*10
-5 mol dm
-3I rearranged Ka as follows- [H+]=Ka*[CH3CH2COOH] / [CH3CH2COO-]
I then used the assumptions to fill in the values- [H+]=1.3*10
-5 *0.100 / 0.100
Then with the value for [H+]- -log[H+] to get a pH of 4.9
Hopefully someone can follow my working and tell me if it is correct