pH = pKa + log (base)/(acid)
pH = 4.87
pKa = 4.87
Therefore,
4.87 = 4.87 + log (base)/(acid)
and (base)/(acid) = 1 which means
(base) = (acid)
If you lower the (H3O^+), that raises the pH so let's substitute a higher number for pH, say 5.87 and see what happens.
5.87 = 4.87 + log (base)/(acid)
1 = log (base)/(acid) and
(base)/(acid) = 10 or
(base) = 10(acid)
which means base predominates by a factor of 10 over the acid.
The base is CH3CH2COO^-. You must draw the structures and any charges since we can't do that on this forum.
The pKa of propanoic acid (propionic acid), CH3CH2COOH, is 4.87. Consider an equilibrium mixture of propanoic acid and its conjugate base with a pH of 4.87. Draw the structure of the form (acid or conjugate base) that predominates after a decrease in [H3O ]. Include all hydrogen atoms and any appropriate formal charges.
2 answers
What is the PH of 0.02 mol/L solution of propanoic acid, given that the pKa value is 4.87