بسم الله الرحمن الرحيم. Preparation and Properties of Buffers. UMM AL-QURQ UNIVERSITY Faculty of Medicine Dep. Of BIOCHEMISTRY. Objectives:. To prepare Buffer solutions. To show that the pH of buffer changes on dilution. To show that the buffer capacity varies with ionic strength.
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Preparation and Properties of Buffers
UMM AL-QURQ UNIVERSITY
Faculty of Medicine
Dep. Of BIOCHEMISTRY
Buffer solution is a solution of conjugate acid/base pair that resists changes in pH as a result of dilution or the addition of small amount of strong acid or base.
It can be prepared either by mixing weak acid with its conjugate base (salt), or by adding small amount of strong base to weak acid or by adding small amount of strong acid to weak base.
Buffers are used in experiments or applications whenever the pH of a solution is needed to be maintained constant or at a predetermined level.
HA + H2O H3O+ + A- Ka=[H3O+][A-]/[HA]
A- + H2O OH- + HA Kb= [OH-][HA]/[A-]
[H3O+] = Ka. [HA]/[A-]
pH = pKa + log ([A-]/[HA])
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