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Buffers

Buffers. Buffers are mixtures of weak acids with their conjugate bases or weak bases with their conjugate acids A buffer resists change in pH when a limited amount of acid or base is introduced

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Buffers

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  1. Buffers • Buffers are mixtures of weak acids with their conjugate bases or weak bases with their conjugate acids • A buffer resists change in pH when a limited amount of acid or base is introduced • If a base is added to a buffer, the acid reacts,if an acid is added to a buffer, the base reacts. Chemtoons

  2. Example Buffer Solution: CH3COOH(aq) / CH3COO-(aq) 1) add acid to the solution: CH3COO-(aq) + H3O+ (aq)  CH3COOH (aq) + H2O (l) 2) add base to the solution: CH3COOH (aq) + OH- (aq)  CH3COO- (aq) + H2O (l) -there is a limit to how much a buffer will maintain pH, add enough base or acid and pH changes.

  3. To Prepare an Effective Buffer • mix equal amounts of a weak acid and its conjugate base (or weak base and conjugate acid) • Ex. mix ethanoic acid and sodium ethanoate. • alternative method: small amount of strong base to an excess of weak acid or a small amount of strong acid to an excess of weak base

  4. LeChatelier and Buffers • Buffer system: CH3COOH(aq) + H2O(l) H3O+(aq) + CH3COO- (aq) -add H3O+(aq) and shifts left to use up H3O+(aq) -add OH- which reacts with H3O+(aq), so shifts right to replace H3O+(aq)

  5. Application of Buffers • HCO3-(aq) /CO32-(aq) maintain blood pH of 7.4 • pH effects hemoglobin transport

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