3. Acids and Bases

Rank the compounds in each set in order of increasing acid strength.

(c)

Rank the compounds in each set in order of increasing acid strength.

(b) CH₃CH₂CH₂CHBrCOOH, CH₃CH₂CHBrCH₂COOH, CH₃CHBrCH₂CH₂COOH

Rank the compounds in each set in order of increasing acid strength.

(a) CH₃CH₂COOH, CH₃CHBrCOOH, CH₃CBr₂COOH

Explain why the C-3 OH group of vitamin C is more acidic than the C-2 OH group.

Explain the difference in the pK_a values of the carboxyl groups of alanine, serine, and cysteine

p-Nitrophenol (pK_a = 7.2) is ten times more acidic than m-nitrophenol (pK_a = 8.4) Explain.

Which proton, H_a or H_b, would you expect to have the lower pK_a value?

Which is the most stable base in each pair?

(a)

Which is the most acidic compound in each pair?

(b) HF vs. HCl

Which is the most acidic compound in each pair?

(c)

Using qualitative reasoning for the acid–base reactions shown,

(i) which is stronger, the base or the conjugate base?

(ii) Which side of the reaction is favored?

(iii) Would you expect a K_eq greater than or less than 1?

(c)

Rank the following alcohols in order of descending pK_a value. Explain your ranking.

The nitrogen screened in purple in Figure 4.43 is not protonated at physiological pH. Why?

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Which is the most stable base in each pair?

(b) HS^– and HO^–

Identify the stronger base in each pair. Explain your choice. Citing pK_a values is not an acceptable answer.

(d)