Ch08: BIT Question 1 Homework Unanswered Chapters have discussed acid-base reactions, but both chapters have focused primarily on the reactions of acids and how structure affects acidity. Which of the following best describes the relationship between acidity and basicity for a given molecule? Select all that apply: Multiple answers: You can select more than one option. 1. The greater the acidity of a molecule, the more basic that molecule will be. 2. The greater the acidity of a molecule, the less basic that molecule will be. 3. The greater the acidity of a molecule, the more basic the conjugate base of that molecule will be. 4. The greater the acidity of a molecule, the less basic the conjugate base of that molecule will be. The relationship between acidity and basicity of a molecule cannot be generalized. The relationship between the acidity of a molecule and the basicity of its conjugate base cannot be generalized.
The Correct Answer and Explanation is:
The correct answers are:
- The greater the acidity of a molecule, the less basic that molecule will be.
- The greater the acidity of a molecule, the less basic the conjugate base of that molecule will be.
Explanation:
- Acidity and Basicity Relationship for Molecules:
Acidity and basicity are inversely related. A more acidic molecule tends to be less basic. This can be explained by considering the tendency of acids to donate protons (H⁺). When an acid dissociates, it releases a proton, and the remaining species is the conjugate base. A strong acid is one that dissociates completely or nearly completely, which means its conjugate base is weak because it has little tendency to accept a proton. - Basicity of the Molecule Itself:
As a molecule becomes more acidic, it becomes less able to accept protons, which means its basicity decreases. This is because strong acids have a low tendency to attract protons themselves due to the strong electronegativity or stability of the molecule once protonated. - Basicity of the Conjugate Base:
The conjugate base of a strong acid is weak. A strong acid (like HCl) dissociates completely in solution, and the conjugate base (Cl⁻) has little tendency to accept a proton. Therefore, the stronger the acid, the weaker its conjugate base, which means the conjugate base is less basic. - Generalization of the Relationship:
The relationship between the acidity of a molecule and the basicity of its conjugate base is indeed a generalizable principle, with stronger acids having weaker conjugate bases and weaker acids having stronger conjugate bases. This relationship is fundamental in acid-base chemistry.
Thus, the stronger the acidity, the weaker both the molecule’s own basicity and its conjugate base’s basicity. This inverse relationship is an essential concept in understanding acid-base reactions and equilibrium.
