You wish to make a buffer with a pH of 11. A) Which of the following...

You wish to make a buffer with a pH of 11.

A) Which of the following amino acids would you use to make your buffer: glutamine, aspartate, histidine, or tyrosine?

B) Why would your chosen amino acid be better than the others?

C) Start with 0.02M of the base form of your amino acid and calculate the concentration of the acidic form needed to have your buffer at the desire pH of 11. Show your work.

Solutions

Expert Solution

A buffer solution is an aqueous solution of definite pH that only slightly changes pH with the addition of an acid or a base. A basic buffer (pH>7) is similarly made by mixing a weak base and its conjugate acid.

Solutions of amino acids are buffers. This means they resist changes in pH when an acid or an alkali is added to an amino acid in solution.

When an acid is added, the -NH₂ group combines with H⁺ ions from the acid to form -NH₃⁺

NH₂CHRCOOH (aq) + H⁺ (aq) NH₃⁺CHRCOOH (aq)
(H⁺ is frequently used as shorthand for H₃O⁺)

When an alkali is added, the -COOH group combines with OH^- ions from the alkali by loss of H⁺ to form
-COO^-

NH₂CHRCOOH (aq) + OH^- (aq) NH₂CHRCOO^- (aq) + H₂O

In both cases, the concentration of H⁺ ions in solution does not change greatly and so the pH remains about the same.

I will select the Histidine see the pk values in above table(9.2)

queen_honey_blossom answered 1 year ago

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