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Pronunciation: bŭf′ĕr


  1. A mixture of an acid and its conjugate base (salt), such as H2CO3 or HCO3−; H2PO4−/HPO42−, that, when present in a solution, reduces any changes in pH that would otherwise occur in the solution when acid or alkali is added to it; thus, the pH of the blood and body fluids is kept relatively constant (pH 7.45) although acid metabolites are continually being formed in the tissues and CO2 is lost in the lungs.
  2. To add a buffer to a solution and thus give it the property of resisting a change in pH when it receives a limited amount of acid or alkali.

See Also: conjugate acid-base pair

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