# How to make a buffer using HClO

If we plan to prepare a buffer with the $\mathrm{pH}$ of $7.35$ using $\ce{HClO}$ ($\mathrm pK_\mathrm a = 7.54$), what mass of the solid sodium salt of the conjugate base is needed to make this buffer? Suppose you want to use $\pu{125.0mL}$ of $\pu{0.500M}$ of the acid.

I know this relates to Henderson's equation, so I do:

$$7.35=7.54+\log{\frac{[\ce{ClO-}]}{[\ce{HClO}]}},$$

which becomes:

$$0.646=\frac{[\ce{ClO-}]}{[\ce{HClO}]}.$$

But I do not know how to go from there, and I don't know how to use the last piece of information in the problem: ("Suppose you want to use $\pu{125.0mL}$ of $\pu{0.500M}$ of the acid").

• Hello and welcome to the Chemistry.SE! You should take the tour to get to know our community and learn how to ask questions. As it stands now, you title is way too long and unclear. Try to state one clearly formulated question. – Fl.pf. Apr 7 '17 at 7:30