pH value of a buffer solution of HClO and NaClO
You're close.  Everything is correct, except that when you take the ratio of concentrations in the H-H equation that ratio is not in moles.   It's just a number, because you divide moles by moles .  Rule of thumb: logarithms and exponential should never involve anything with units.  So don't include the molar unit under the logarithm and you're good.