Tahani Alshehri Tmalshehri@ksu.edu.sa 2009 Preparation of the buffer solutions, titration of amino acid and there buffering capacity Tahani Alshehri Tmalshehri@ksu.edu.sa 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 equation The 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.