Electrostatic potential maps of acetic acid (CH₃CO₂H) and ethyl alcohol (CH₃CH₂OH) are shown. Identify the most acidic hydrogen in each, and tell which of the two is likely to be the stronger acid.

Verified step by step guidance

1. Identify the acidic hydrogen in acetic acid (CH₃CO₂H) by looking for the hydrogen atom attached to the oxygen in the carboxyl group (COOH).
2. Identify the acidic hydrogen in trifluoroacetic acid (CF₃CO₂H) by looking for the hydrogen atom attached to the oxygen in the carboxyl group (COOH).
3. Compare the electrostatic potential maps: red areas indicate regions of high electron density, while blue areas indicate regions of low electron density.
4. Note that the presence of electronegative atoms like fluorine in CF₃COOH increases the acidity by stabilizing the negative charge on the conjugate base.
5. Conclude that CF₃COOH is likely the stronger acid due to the electron-withdrawing effect of the fluorine atoms, which stabilizes the conjugate base more effectively than in CH₃COOH.

Key Concepts

Acidity and Acidic Protons

Acidity refers to the ability of a substance to donate protons (H⁺ ions) in a chemical reaction. The acidic protons in a molecule are typically those attached to electronegative atoms, such as oxygen in carboxylic acids. In acetic acid (CH₃COOH), the hydrogen in the carboxyl group (-COOH) is the most acidic, while in ethyl alcohol (CH₃CH₂OH), the hydroxyl group (-OH) contains the acidic hydrogen.

Electrostatic Potential Maps

Electrostatic potential maps visually represent the distribution of electron density in a molecule, indicating regions of positive and negative charge. Areas of high electron density are shown in red and yellow, while low density appears in blue and green. These maps help identify the most acidic hydrogen by highlighting the regions where protons are more likely to dissociate, thus indicating acidity.

Comparative Acidity

Comparative acidity involves evaluating the strength of acids based on their ability to donate protons. Factors influencing acidity include the stability of the conjugate base formed after deprotonation and the electronegativity of atoms attached to the acidic hydrogen. In this case, acetic acid is generally a stronger acid than ethyl alcohol due to the resonance stabilization of its conjugate base, acetate, compared to the ethoxide ion formed from ethyl alcohol.