What is an alternate way of preparing a sodium hydrogen phosphate/sodium dihydrogen phosphate buffer through titrating an acid with a strong base?
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You want a mixture of $\ce{HPO4^2-}$ and $\ce{H2PO4^-}$. You can start with any species (in a solution with a certain pH) and add another species whose pH is &quot;on the other side&quot; of the desired pH. If the pH of your starting solution is lower than the desired pH, you can also titrate with NaOH.
What you actually do (of the six options) is determined by solubility of the solution and by availability. If you titrate two phosphate solutions of the same concentration, there will be no dilution effect. If you titrate with NaOH, you would used fairly concentrated NaOH to avoid dilution, but would have to add water to a defined volume (or measure the volume after reaching your desired pH) to figure out the concentration of your buffer.
You should not titrate with HCl because then you end up with extra sodium choride in your buffer.