I have a problem I'm struggling to solve. There's something fundamental I'm missing here.
The problem asks us to describe how to create a 500ml buffer with a pH of 2.4.
My first problem is that I don't know which compounds to use. I understand that there's some equation we can use whereby the ratio of the concentrations of the two compounds, [Compound1]/[Compound2] = [H+]/Ka.
An example in my book uses acetic acid and sodiumacetate, and demonstrates using HC2H3O2 and C2H3O2-.
If I want to use the same substances, could I do the following?
[HC2H3O2] / [C2H3O2-] = [H+] / Ka.
[H+] for a compound with pH=2.4 is 10-2.4. But what is Ka? Does it vary? The example uses 1.8*10-5, but I'm not sure if this is constant.
Am I on the right track here?