what is the buffer component ratio CH3CH2COOCH3CH2COOH of a

what is the buffer component ratio ([CH3CH2COO-]/[CH3CH2COOH]) of a propanate buffer that has a pH of 5.43. Ka of Ch3CH2COOH is 1.3E-5.

Ok. so...I thought I could use the H/H equation to calculate the answer. I guess Im wrong. My teacher used the Ka expression to find the answer and it doesnt match the answer I get using H/H.

Why cant I use H/H for this? What am I missing. Please explain the difference

Solution

No ,i think your teacher had done some mathematical mistake!

i think she used Ka for calculating Pka = - log(Ka),which is a part of H/H equation !

This kind of problems are only solved using H/H equations,,thats for sure !