Buffer: Difference between revisions
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mentioned that if too much acid/alkali added then buffer rendered useless. |
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A buffer by definition resists small changes in the [[PH|pH]] of a solution (it maintains the pH). A buffer must contain the chemical species for “neutralizing” added amounts of [[Acid|acid]] or [[Base|base]]. Generally, a buffer is a solution of a [[Weak acid|weak acid]] and its conjugate [[Base|base]] (e.g. acetic acid and sodium acetate) or a [[Weak base|weak base]] and conjugate acid (e.g. ammonia and ammonium chloride). If there is a lot of acid or alkali added then the buffer will not be able to cope with such a change and will no longer able to maintain the pH. | A buffer by definition resists small changes in the [[PH|pH]] of a solution (it maintains the pH). A buffer must contain the chemical species for “neutralizing” added amounts of [[Acid|acid]] or [[Base|base]]. Generally, a buffer is a solution of a [[Weak acid|weak acid]] and its conjugate [[Base|base]] (e.g. [[acetic acid|acetic acid]] and [[sodium acetate|sodium acetate]]) or a [[Weak base|weak base]] and conjugate acid (e.g. [[ammonia|ammonia]] and [[ammonium chloride|ammonium chloride]]). If there is a lot of acid or alkali added then the buffer will not be able to cope with such a change and will no longer able to maintain the pH. | ||
Buffers are most effective in the range [[PH]] = pK’a ± 1. Outside the range the [[Concentration|concentration]] of either the [[Acid|acid]] or the conjugate [[Base|base]] is too small to effectively resist the effect of added hydrogen or hydroxide [[Ion|ions]].<br> | Buffers are most effective in the range [[PH]] = pK’a ± 1. Outside the range the [[Concentration|concentration]] of either the [[Acid|acid]] or the conjugate [[Base|base]] is too small to effectively resist the effect of added [[Hydrogen|hydrogen]] or [[hydroxide|hydroxide]] [[Ion|ions]].<br> | ||
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Revision as of 19:45, 20 October 2016
A buffer by definition resists small changes in the pH of a solution (it maintains the pH). A buffer must contain the chemical species for “neutralizing” added amounts of acid or base. Generally, a buffer is a solution of a weak acid and its conjugate base (e.g. acetic acid and sodium acetate) or a weak base and conjugate acid (e.g. ammonia and ammonium chloride). If there is a lot of acid or alkali added then the buffer will not be able to cope with such a change and will no longer able to maintain the pH.
Buffers are most effective in the range PH = pK’a ± 1. Outside the range the concentration of either the acid or the conjugate base is too small to effectively resist the effect of added hydrogen or hydroxide ions.