preparation of the buffer solutions, titration of amino acid and there buffering capacity tahani...
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Preparation of the buffer solutions, titration of amino acid
and there buffering capacity
Tahani Alshehri [email protected]
2009
Objective
• To Study the nature of the buffers
Introduction & principle
• Buffer solution – a solution which resist the changes in pH upon
addition of small amounts of acid or base, or upon dilution
– Is a the weak acid and its salt in strong base in a buffer a solution .
Acidic buffer solutions
• An acidic buffer solution is simply one which has a pH less than 7.
• Acidic buffer solutions are commonly made from a weak acid and one of its salts - often a sodium salt.
Alkaline buffer solutions
• An alkaline buffer solution has a pH greater than 7.
• Alkaline buffer solutions are commonly made from a weak base and one of its salts.
?
• ethanoic acid and sodium ethanoate• ammonia solution and ammonium chloride
solution
Acidic buffer solutions
• We'll take a mixture of acetic acid and sodium acetate as typical.
• acetic acid is a weak acid
• Buffers are main important in regulating the pH of the body fluids and tissues within limits consistants with life and normal function
• Many body chemical reaction including those catalyzed by enzyme require pH control which is provided by buffers
• Mammalian tissue in the resting state have a pH of about 7.4
Henderson–Hasselbalch equationThe pH of the buffer is given by Henderson–Hasselbalch equation
Which for practical purposes , becomes
Here, pKa is − log(Ka) where Ka is the acid dissociation constantof the acid
How do buffer solutions work?
• A buffer solution has to contain compounds which will remove any hydrogen ions or hydroxide ions that you might add to it - otherwise the pH will change.
• Acidic and alkaline buffer solutions achieve this in different ways.