InterviewSolution
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InterviewSolution
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Towards which electrode would an alpha-amino acid migrate in an electric field at (i) p H lt p I, (ii) p H gt p I and (iii) p H=p I? Explain. |
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Answer» <P> Solution :The general formula of an amino acid is`H_(3)overset(+)N-UNDERSET("Zwitterion")underset(R)underset(|)(CH)-COO^(-)overset(H^+)underset(OH^-)hArrH_(3)overset(+)N-underset((I))underset(R)underset(|)(CH)-COOHoverset(H^-)underset(OH^+)hArrH_2N-underset((II))underset(R)underset(|)(CH)-COO^(-)` (i) Which `p H lt p I`, i.e., the solution is acidic , the cation (I) predominates and therefore , the amino acid MIGRATES towards cathode. (ii) When `pH GT pI `, i.e., the solution is basic the anion (II) predominates, therefore , the acid migrates towards anode. (iii) When `pH=pI` , the amino acid predominantly exists as a zwitterion. That is there is no net charge on the amino acid and hence it does not migrate. |
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