Chapter 2, Problem 53P

Which is a stronger base?

1. a. HS^– or HO^–
2. b. CH₃O^– or CH₃ $\stackrel{\text{+}}{\text{N}}$H
3. c. CH₃OH or CH₃O $\stackrel{\text{+}}{\text{N}}$
4. d. Cl^– or Br^–
5. e. CH₃COO^– or CF₃COO^–
6. f. CH₃CHClCOO^– or CH₃CHBrCOO^–

Interpretation Introduction

Interpretation:

The stronger base among $H{S}^{-}$ and $H{O}^{-}$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity:

The chemical behavior of an atom where it attracts the shared electron pair to itself. Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$H{O}^{-}$ is the stronger base.

Explanation of Solution

If an acid lose one proton, then the formed species is a conjugated base. The stronger base is more likely to get protonated. Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base. Electronegativity increases as the size of the atom decreases. Thus, atom with small size is more basic since stability is determined by the size of the atom rather than electronegativity. Oxygen atom has least volume comparing to sulfur atom. Therefore, $H{O}^{-}$ is the stronger base.

Interpretation Introduction

Interpretation:

The stronger base among $C{H}_3{O}^{-}$ and $C{H}_3\stackrel{-}{N}H$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity:

The chemical behavior of an atom where it attracts the shared electron pair to itself.  Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$C{H}_3\stackrel{-}{N}H$ is the stronger base.

Explanation of Solution

If an acid lose one proton, then the formed species is a conjugated base.  The stronger base is more likely to get protonated.  Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.  Electronegativity increases as the size of the atom decreases.  Thus, atom with small size is more basic since stability is determined by the size of the atom rather than electronegativity. Nitrogen atom has least volume comparing to oxygen atom.  Therefore, $C{H}_3\stackrel{-}{N}H$ is the stronger base.

Interpretation Introduction

Interpretation:

The stronger base among $C{H}_{3}OH$ and $C{H}_3{O}^{-}$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity:

The chemical behavior of an atom where it attracts the shared electron pair to itself. Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$C{H}_3{O}^{-}$ is the stronger base.

Explanation of Solution

If an acid lose one proton, then the formed species is a conjugated base. The stronger base is more likely to get protonated. In $C{H}_3{O}^{-}$, the negative charge is stabilizes the compound making it a strong base. Nitrogen atom has least volume comparing to oxygen atom. Therefore, $C{H}_3{O}^{-}$ is the stronger base.

Interpretation Introduction

Interpretation:

The stronger base among $C{l}^{-}$ and $B{r}^{-}$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity:

The chemical behavior of an atom where it attracts the shared electron pair to itself. Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$C{l}^{-}$ is the stronger base.

Explanation of Solution

If an acid lose one proton, then the formed species is a conjugated base.  The stronger base is more likely to get protonated. Electronegativity depends on the acidity of a species.  The species having high electronegativity is the strongest base.  Electronegativity increases as the size of the atom decreases.  Thus, atom with small size is more basic since stability is determined by the size of the atom rather than electronegativity. $C{l}^{-}$ has least volume comparing to $B{r}^{-}$.  Therefore, $C{l}^{-}$ is the stronger base.

Interpretation Introduction

Interpretation:

The stronger base among $C{H}_{3}CO{O}^{-}$ and $C{F}_{3}CO{O}^{-}$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity:

The chemical behavior of an atom where it attracts the shared electron pair to itself. Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$C{H}_{3}CO{O}^{-}$ is the stronger base.

Explanation of Solution

In hydrocarbons, if hydrogen atoms are replaced by electronegative atoms, it causes inductive effect due to electron withdrawing nature of electronegative atoms.  This effect stabilizes its conjugate base thus increases the strength of the acid.  The conjugated base of a weak acid is very strong.  As the electronegativity of substituent increases, the greater will be the inductive effect and so electron withdrawal of the substituent.  Thus the acid of brominated compound is weak.  Therefore, $C{H}_{3}CO{O}^{-}$ is the stronger base.

Interpretation Introduction

Interpretation:

The stronger base among $C{H}_{3}ClCO{O}^{-}$ and $C{H}_{3}BrCO{O}^{-}$ has to be identified.

Concept introduction:

If a base receives one proton, then the formed species is a conjugate acid whereas an acid lose one proton, then the formed species is a conjugated base.

If an acid lose one proton, then the formed species is a conjugated base. Weak base forms stronger conjugated acid.

Electronegativity: The chemical behavior of an atom where it attracts the shared electron pair to itself. Down the group, electronegativity decreases as the number of energy levels increases.

Electronegativity depends on the acidity of a species. The species having high electronegativity is the strongest base.

Answer to Problem 53P

$C{H}_{3}CHBrCO{O}^{-}$ is the stronger base.

Explanation of Solution

In hydrocarbon, if hydrogen atoms are replaced by electronegative atoms, it causes inductive electron withdrawal. It stabilizes its conjugate base thus increases the strength of the acid. The conjugated base of a weak acid is very strong. As the electronegativity of substituent increases, the greater will be the inductive electron withdrawal of the substituent. Electronegativity increases as the size of the atom decreases. Comparing to fluorine, chlorine is less electronegative and thus the acid of chlorinated compound is weak. Therefore, $C{H}_{3}CHBrCO{O}^{-}$ is the stronger base.

Conclusion

The stronger base among the following pairs was determined.