*Equivalents of NaOH = Volume ¥ concentration.
mequiv. = mL ¥ 1.0 M (i.e. mequiv. = 10-3 ¥ equivalents.)
Graph of the calculated results:
The buffer concentration = 10 mequiv/100 mL = 100 mM or 0.10 M.
The pKa = 7.5-7.6. (The pH at 5.0 mequiv.)
From Table 2.7 of Campbell, the "Good" buffer is either HEPES or TES.
HEPES.xls is the Excel spreadsheet used to calculate and graph these results; it can be copied to your disk.