What is the [ch3co2-]/[ch3co2h] ratio necessary to make a buffer solution with a ph of 4.34? ka = 1.8 * 10-5 for ch3co2h?

According to Henderson-Hasselbalch Equation,

pH = pKa + log [Acetate] / [Acetic Acid]

As,

pKa = - log Ka

pKa = - log (1.8 * 10⁻⁵)

pKa = 4.74

So,

pH = 4.74 + log [Acetate] / [Acetic Acid]

4.34 = 4.74 + log [Acetate] / [Acetic Acid]

4.34 - 4.74 = log [Acetate] / [Acetic Acid]

-0.40 = log [Acetate] / [Acetic Acid]

Taking Antilog on both sides,

[Acetate] / [Acetic Acid] = 0.398