I had to calculate the conjugate base/acid ratio of phenol red in a phenol red solution prepared with a buffer I made and the base/acid ratio of just the phosphate buffer I made. I need to understand why these ratios are different. Can anyone help?

Question

I had to calculate the conjugate base/acid ratio of phenol red in a phenol red solution prepared with a buffer I made and the base/acid ratio of just the phosphate buffer I made.  I need to understand why these ratios are different.  Can anyone help?

DrBob222 · Answer

I suggest you write the two structures for each system as the acid + OH^- ==> conj base, plug in the concns from your data and you can see how/why the ratio is different.