Ch. 2 - Acids and Bases; Functional Groups

Wade9th EditionOrganic ChemistryISBN: 9780135213728Not the one you use?Change textbook

Wade 9th Edition

Ch. 2 - Acids and Bases; Functional Groups

Problem 42g,h

Chapter 2, Problem 42g,h

Predict the products of the following acid–base reactions.
(g) HCOOH + CH₃O^– ⇌
(h) ⁺NH₃CH₂COOH + 2 ^–OH ⇌

Verified step by step guidance

Step 1: Identify the acid and base in each reaction. In reaction (g), HCOOH (formic acid) is the acid, and CH3O- (methoxide ion) is the base. In reaction (h), +NH3CH2COOH (aminoacetic acid) is the acid, and -OH (hydroxide ion) is the base.

Step 2: Determine the conjugate base and conjugate acid formed in each reaction. For reaction (g), the acid HCOOH will donate a proton (H+) to the base CH3O-, forming HCOO- (formate ion) and CH3OH (methanol). For reaction (h), the acid +NH3CH2COOH will donate a proton to the base -OH, forming NH2CH2COO- (glycinate ion) and H2O (water).

Step 3: Write the balanced chemical equation for each reaction. For reaction (g), the equation is:

{HCOOH}_{+} {CH 3_{O}}_{-} ⇌ {HCOO}_{-} + CH 3_{OH}

. For reaction (h), the equation is:

+ NH 3_{CH 2_{COOH}} + 2 - OH ⇌ {NH 2_{CH 2_{COO}} -}_{+ H 2_{O}}

Step 4: Consider the equilibrium position of each reaction. The position of equilibrium depends on the relative strengths of the acids and bases involved. Stronger acids and bases will drive the equilibrium towards the formation of weaker conjugate acids and bases.

Step 5: Verify the stability of the products formed. Ensure that the products are stable and make sense chemically. For example, methanol and water are stable products in their respective reactions, and the conjugate bases formed are reasonable given the starting materials.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Acid-Base Reaction

An acid-base reaction involves the transfer of a proton (H+) from an acid to a base. In organic chemistry, this often results in the formation of a conjugate acid and a conjugate base. Understanding the strength and structure of acids and bases helps predict the direction and products of the reaction.

Conjugate Acid-Base Pairs

Conjugate acid-base pairs are related by the gain or loss of a proton. When an acid donates a proton, it forms its conjugate base, and when a base accepts a proton, it forms its conjugate acid. Identifying these pairs is crucial for predicting the products of acid-base reactions.

pKa and Reaction Direction

The pKa value indicates the strength of an acid; lower pKa values mean stronger acids. In acid-base reactions, the equilibrium favors the formation of the weaker acid and base. Comparing the pKa values of the reactants and products helps determine the direction and extent of the reaction.

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Related Practice

Textbook Question

Predict the products of the following acid–base reactions.

(h)

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Textbook Question

Predict the products of the following acid–base reactions.

(f)

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Textbook Question

Compare the relative acidity of 1-molar aqueous solutions of the following acids.

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Textbook Question

Consider the following proposed Brønsted–Lowry acid–base reactions. In each case, draw the products of a transfer of the most acidic proton on the acid to the most basic site on the base. Use Appendix 4 to find or estimate the pK_a values for the acids and the pK_b values for the bases. Then determine which side of the reaction is favored, either reactants or products.

(a)

(b)

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Textbook Question

Predict the products of the following acid–base reactions.

(e) H₂O + NH₃ ⇌

Predict the products of the following acid–base reactions.