4. (a) Consider the three organic structures drawn below. Draw their conjugate bases by deprotonating the indicated hydrogen. Then, draw resonance structures for their conjugate bases. H + H2O H3O++ in H +H₂O H3O++ H + H₂O H3O+ + (b) CIRCLE the conjugate base that is most stable. Underline the original compound with the highest pKa (c) Predict how the pKa of the above compounds will compare to that of a carboxylic acid.

но HO но он The pK, of ascorbic acid (vitamin C) is 4.17, showing that it is slightly more acidic than acetic acid (CH3CO0H, pKa 4.74). (a) Show the fou r different conjugate bases that would be formed by deprotonation of the four different OH groups in ascorbic acid. (b) Compare the stabilities of these four conjugate bases, and predict which OH group of ascorbic acid is the most acidic. (c) Compare the most stable conjugate base of ascorbic acid with the conjugate base of acetic acid, and suggest why these two compounds have similar acidities, even though ascorbic acid lacks the carboxylic acid (COOH) group.

What is the conjugate acid of each of the following? What is the conjugate Dase of eacn? (a) NH Parts of the formula in your answer are transposed. Your answer appears to be missing a charge. Conjugate acid (b ) (CH₂)₂NH \table[[chemPad, (9) Help], [xlx =larr|l, Greek -],[(CH),NH,N What is the conjugate acid of each of the following? What is the conjugate base or eacn (UTIL SOLES- (a) NH3 Conjugate acid Conjugate base (b) (CH3)2NH Conjugate acid Conjugate base chemPad XX→→ chemPad XX→ NH₂ NH 2 NH4 NH 4 Parts of the formula in your answer are transposed. Your answer appears to be missing a charge. chemPad XX→ (CH4)2NH2 (CH_4)_2NH_2 chemPad XX→= Greek (CH₂)2N (CH_2) 2N Help Greek Help Greek X Help Greek juur Help

(i) Draw the dissociation reaction for a carboxylic acid in water and define the Ka for this reaction. Write the equation that relates pKa to Ka.  (ii) A deprotonated carboxylic acid can be drawn in two resonance forms. Draw the two forms and explain what the term “resonance” means. (iii) Draw an energy profile for the above dissociation reaction and describe how the profiles for a strong and a weak acid would differ.