Video Solution: Rank the following in order of decreasing basicity. As in th...

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Rank the following in order of decreasing basicity. As in the preceding problem, Table 1.8 should prove helpful. 

Order the following molecules by increasing pKa values:

CH= CH2 (1), HOEt (2), H2SO4 (3), CH3CH2CH2CH2CO2H (4).

___ < ___ < ___ < ___

 

NH3 (1), CH4 (2), OH2 (3), HF (4).

___ < ___ < ___ < ___

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Considering only the most acidic proton in each molecule ( bold), rank in order of increasing acidity. (1 = least acidic, highest pka; 5 = most acidic, lowest pka)

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Complete the following two structures by adding appropriate numbers of lone pair electrons, H atoms, and formal charges to the atoms in the boxes. You must adjust your answers to indicate the predominant species at each indicated pH value. (You do not have to add anything such as H atoms to atoms not drawn in the boxes.) This problem is testing your understanding of the relationship of protonation state to pH to pKa values for certain functional groups we have discussed. Next, in the space provided, write the overall charge on each structure at the indicated pH. For your reference, here are the relevant pKa values:

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Fill in the appropriate pKa values below. Remember that certain factors will affect these general pKa values.

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Circle the most acidic proton in each of the following molecules.

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Rank the acidity of the labeled protons in the following molecule from lowest to highest acidity. 

 

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Circle the weakest base.

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Glutamic acid, being a constituent of protein, is present in every food that contains protein, but it can only be tasted when it is present in an unbound form. Glutamic acid is often used as a food additive and flavor enhancer when it is sold as its salt monosodium glutamate (MSG). The structure of glutamic acid is given below. Determine the site of deprotonation and convert the structure to the sodium salt. The answer's carbon skeleton is provided to give you a head start on the answer, just fill it in the rest of the way. Label acid, base, conjugate acid, and conjugate base. 

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Which is the order from the most acidic to least acidic?

(A) III > IV > II > I
(B) II > UV > I > III
(C) II > III > IV > I 
(D) IV > II > III > I 

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Rank the following from least to most acidic.

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Which of the indicated protons in this compound would have the smallest pKa value?

a) A

b) B

c) C

d) D

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Which proton in this compound would be most acidic?

A) A

B) B

C) C

D) D

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BONUS: Using pK a values given, what is the major product of the following reaction of the acetylide base with guanine (HCCH/HCC-, pK a = 24)?

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Which statement regarding the two amino acids (phenylalanine & tryptophan) below is true?

A) tryptophan is a stronger acid than phenylalanine as it has a larger pKa

B) tryptophan is a weaker acid than phenylalanine as it has a larger pKa

C) phenylalanine is a stronger acid than tryptophan as it has a smaller pKa

D) phenylalanine is a weaker acid than tryptophan as it has a smaller pKa

E) B) and C) are both true 

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Identify the strongest Bronsted acid:

 

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Order the following in increasing order of acidity.

Hl, Acetic Acid, Ethanol, and Octane. 

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Consider the acidity/basicity of each group on the main molecule.

A) Determine the site of protonation/deprotonation in the reactant and use electron arrows to react the structures with the acid or base provided to produce the correct corresponding salt. The answer’s skeleton is provided to give you a head start on the answer.

B) Label acid, base, conjugate acid and conjugate base for each reaction. 

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Consider the acidity/basicity of each group on the main molecule. 

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Which one has the lowest pKa?

a) HO

b) H2O

c) H3O+

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​​Circle the least acidic proton in the following compound and explain your answer.

 

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Hydrogen atom(s) from which position(s) is/are most easily abstracted when the following organic compound is treated with BuLi?

 

a. 1

b. 7

c. 3, 4

d. 1, 6, 7, 8

e. 1, 3, 4, 7

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Rank the acidity of the labeled protons in the following molecule from the most acidic to least acidic:

 

a. Hb > Ha > Hc

b. Ha > Hb > Hc

c. Hc > Hb > Ha

d. Hc > Ha > Hb

e. Hb > Ha > Hc

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