The following compounds can all react as bases.

a. For each compound, show its conjugate acid. Show any resonance forms if applicable.

Verified step by step guidance

1. Identify the base in each compound and determine the site where protonation will occur to form the conjugate acid. For amines like CH3CH2NH2 and CH3CONH2, the nitrogen atom is the basic site. For NaOH and NaNH2, the hydroxide (OH-) and amide (NH2-) ions are the basic sites, respectively. For CH3CH2OH, the oxygen atom in the hydroxyl group is the basic site.
2. For each compound, add a proton (H+) to the basic site to form the conjugate acid. For example, CH3CH2NH2 becomes CH3CH2NH3+, CH3CONH2 becomes CH3CONH3+, NaOH becomes H2O, CH3CH2OH becomes CH3CH2OH2+, and NaNH2 becomes NH3.
3. Consider resonance stabilization for each conjugate acid. CH3CONH3+ can have resonance structures due to the carbonyl group adjacent to the nitrogen, which can delocalize the positive charge. This is not possible for the other conjugate acids.
4. Evaluate the stability of each conjugate acid based on factors such as resonance, electronegativity, and the inductive effect. Resonance-stabilized conjugate acids are generally more stable. The presence of electronegative atoms or groups can also stabilize the positive charge through the inductive effect.
5. Rank the conjugate acids from most stable to least stable based on the analysis. Consider that resonance and inductive effects play significant roles in determining stability. The more resonance-stabilized or inductively stabilized the conjugate acid, the more stable it is.

Key Concepts

Conjugate Acid-Base Pairs

In acid-base chemistry, a conjugate acid-base pair consists of two species that transform into each other by the gain or loss of a proton. When a base accepts a proton, it forms its conjugate acid. Understanding this relationship is crucial for predicting the behavior of compounds in acid-base reactions and determining the stability of conjugate acids.

Resonance Stabilization

Resonance stabilization occurs when a molecule can be represented by two or more valid Lewis structures, which helps distribute charge across the molecule. This distribution can enhance the stability of the molecule, particularly in conjugate acids, by delocalizing positive charge. Recognizing resonance forms is essential for assessing the relative stability of different conjugate acids.

Acid Stability and Electronegativity

The stability of conjugate acids is influenced by the electronegativity of atoms involved and the ability to stabilize positive charge. More electronegative atoms can better stabilize positive charges, making the conjugate acid more stable. Additionally, the presence of electron-withdrawing groups can enhance stability by dispersing charge, which is key in ranking the stability of conjugate acids.