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Chapter 10: Problem 162

In each equilibrium, label the stronger acid, the stronger base, the weaker arid, and the weaker base. Also estimate the position of each equilibrium. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{CH}_{3} \mathrm{CHH} \rightleftharpoons \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{CH}_{3}=\mathrm{C}^{-}\) (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{HCl} \rightleftharpoons \mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}+\mathrm{Cl}^{-}\) (c) \(\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-} \rightleftharpoons \mathrm{CH}_{3} \mathrm{COO}^{-}+\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{OH}\) Reactions of Alcohols

Short Answer

Expert verified
Question: In each given equilibrium, label the stronger acid, stronger base, weaker acid, and weaker base. Also, estimate the position of the equilibrium. (a) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{CH}_{3}\mathrm{CHH} \rightleftharpoons \mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}+\mathrm{CH}_{3}=\mathrm{C}^{-}\) Answer: In this equilibrium, the stronger acid is \(\mathrm{CH}_{3}\mathrm{CHH}\), the stronger base is \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}\), the weaker acid is \(\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}\), and the weaker base is \(\mathrm{CH}_{3}=\mathrm{C}^{-}\). The position of the equilibrium lies to the right. (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{HCl}\rightleftharpoons \mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}+\mathrm{Cl}^{-}\) Answer: In this equilibrium, the stronger acid is \(\mathrm{HCl}\), the stronger base is \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}\), the weaker acid is \(\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}\), and the weaker base is \(\mathrm{Cl}^{-}\). The position of the equilibrium lies to the right. (c) \(\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{O}^{-} \rightleftharpoons \mathrm{CH}_{3}\mathrm{COO}^{-}+\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}\) Answer: In this equilibrium, the stronger acid is \(\mathrm{CH}_{3}\mathrm{COOH}\), the stronger base is \(\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{O}^{-}\), the weaker acid is \(\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}\), and the weaker base is \(\mathrm{CH}_{3}\mathrm{COO}^{-}\). The position of the equilibrium lies to the right.

Step by step solution

01

Identify the Acid/Base Pairs

In this equilibrium, the acid/base pairs are: (\(\mathrm{CH}_{2}\mathrm{CH}\mathrm{O}^{-}\), \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\)) and (\(\mathrm{CH}_{3}\mathrm{CHH}\), \(\mathrm{CH}_{3}=\mathrm{C}^{-}\)).
02

Compare Acid/Base Strengths

To determine which species is the stronger or weaker acid or base, we can look at their pKa values. The pKa values are: 16 for \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\) (ethanol) and 25 for \(\mathrm{CH}_{3}\mathrm{CHH}\). From this, we can conclude that \(\mathrm{CH}_{3}\mathrm{CHH}\) is the stronger acid and \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{O}^{-}\) is the stronger base, while \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\) is the weaker acid and \(\mathrm{CH}_{3}=\mathrm{C}^{-}\) is the weaker base.
03

Estimate Equilibrium Position

Since the stronger acid and the stronger base are reacting, their pKa values indicate the reaction will lie to the right. The weaker acid and the weaker base will be major products in the equilibrium. (b) \(\mathrm{CH}_{3} \mathrm{CH}_{2} \mathrm{O}^{-}+\mathrm{HCl}\rightleftharpoons \mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}+\mathrm{Cl}^{-}\)
04

Identify the Acid/Base Pairs

In this equilibrium, the acid/base pairs are: (\(\mathrm{CH}_{2}\mathrm{CH}\mathrm{O}^{-}\), \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\)) and (\(\mathrm{HCl}\), \(\mathrm{Cl}^{-}\)).
05

Compare Acid/Base Strengths

The pKa values are: -7 for \(\mathrm{HCl}\) and 16 for \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\). Therefore, \(\mathrm{HCl}\) is the stronger acid, and \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{O}^{-}\) is the stronger base, while \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\) is the weaker acid and \(\mathrm{Cl}^{-}\) is the weaker base.
06

Estimate Equilibrium Position

This reaction will favor the products (right side) as the strong acid and strong base react completely to form a weaker acid/base pair. (c) \(\mathrm{CH}_{3} \mathrm{COOH}+\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{O}^{-} \rightleftharpoons \mathrm{CH}_{3}\mathrm{COO}^{-}+\mathrm{CH}_{3} \mathrm{CH}_{2}\mathrm{OH}\)
07

Identify the Acid/Base Pairs

In this equilibrium, the acid/base pairs are: (\(\mathrm{CH}_{3}\mathrm{COOH}\), \(\mathrm{CH}_{3}\mathrm{COO}^{-}\)) and (\(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{O}^{-}\), \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\)).
08

Compare Acid/Base Strengths

The pKa values are: 4.75 for \(\mathrm{CH}_{3}\mathrm{COOH}\) (acetic acid) and 16 for \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\). Thus, \(\mathrm{CH}_{3}\mathrm{COOH}\) is the stronger acid and \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{O}^{-}\) is the stronger base, while \(\mathrm{CH}_{3}\mathrm{CH}_{2}\mathrm{OH}\) is the weaker acid and \(\mathrm{CH}_{3}\mathrm{COO}^{-}\) is the weaker base.
09

Estimate Equilibrium Position

This reaction will again lie to the right side as the stronger acid and base react to form the weaker acid/base pair.

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Most popular questions from this chapter

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