Question

A common biological buffer is a "Phosphate Buffer," which involves the equilibrium between H2PO4^- and H2PO4^2- , with a pKa at 25 degree celcius of 6.86. Describe in words how you would prepare 500.mL of 0.250 M phosphate buffer at pH= 7.2, given appropiate glassware and 500.mL each of 0.250 M NaH2PO4 and 0.250 M Na2HPO4 at 25⁰ C. (Note: your explanation needs to include actual volumes, so this question requires calculations! It will be helpful to know that the concentration of each component must add to the buffer concentration. i.e. [A^-] + [HA]= 0.250 M).

Please use both words and calculation to understand.

Answer 1