alleryStart learning →Which pair is chiefly responsible for buffering human blood?
APhosphoric acid and dihydrogen phosphate
BAmmonium ion and dissolved ammonia in it
CCarbonic acid and the hydrogen carbonate ion
DAcetic acid and the acetate ion in the plasma
Answer & Solution
Correct answer: C. Carbonic acid and the hydrogen carbonate ion
1. Blood must hold its pH within a very narrow band to stay functional.
2. The principal buffering pair is carbonic acid with the hydrogen carbonate ion.
3. Added hydronium is removed by hydrogen carbonate, forming carbonic acid and water.
4. Added hydroxide is removed by carbonic acid, forming hydrogen carbonate and water.
5. Breathing rate adjusts the dissolved carbon dioxide and so tunes the same equilibrium.
_Source: OpenStax Chemistry (CC BY 4.0), Ch 14 "Acid-Base Equilibria", section 14.6 Buffers_
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