How would you use the Henderson-Hasselbalch equation to calculate the ratio of H2CO3 to HCO3- in blood having a pH of 7.40?

1 Answer
anor277
Nov 15, 2015

#pH = pK_a + log_(10){[A^-]/[HA]}#. Clearly, we need #pK_a# for #H_2CO_3#, i.e. #pK_a = 6.35.#

Explanation:

If #pH= 7.40#, then #log_(10){[HC(=O)O^-]/[HC(=O)OH]}# #=# #1.05#. This reasonable because the #pH# is higher than the #pK_a# and there should be more carbonate than carbonic acid.

Thus #{[HC(=O)O^-]/[HC(=O)OH]}# #=# #10^(1.05)# #=# #??#

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