The 0 025 0 m KH2PO4 0 025 0 m Na2HPO4 buffer (6) in Table 14 3 has a pH of 6 865 at 25C (a) Show that the ionic strength of the buffer is 0 100 m (b) From the pH and K2 for phosphoric acid, find the quotient of activity coefficients, , at 0 100 m (c) You have the urgent need to prepare a pH 7 000 ...

a b c There is negligible change in the concentrations of the buffer species when we mix the acid HP ...

The 0.025 0 m KH2PO4/0.025 0 m Na2HPO4 buffer (6) in Table 14-3 has a pH of

Question:

The 0.025 0 m KH2PO4/0.025 0 m Na2HPO4 buffer (6) in Table 14-3 has a pH of 6.865 at 25°C.
(a) Show that the ionic strength of the buffer is μ = 0.100 m.
(b) From the pH and K2 for phosphoric acid, find the quotient of activity coefficients, , at = 0.100 m.
(c) You have the urgent need to prepare a pH 7.000 buffer to be used as a calibration standard.45 You can use the activity coefficient ratio from part (b) to accurately prepare such a buffer if the ionic strength is kept at 0.100 m. What molalities of KH2PO4 and Na2HPO4 should be mixed to obtain a pH of 7.000 and μ = 0.100 m?