Consider the molecular models shown here, where X represents a halogen atom. (b) Does the acidity of each molecule increase or decrease as the electronegativity of the atom X increases?

Name: Identifying Acids and Bases
Uploaded: 2022-07-23T00:00:00.000Z
Duration: 50 s
Description: Watch the video explanation for the concept: Identifying Acids and Bases

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Identify the relationship between electronegativity and acidity. Generally, as electronegativity increases, the ability of an atom to attract electrons increases, which can affect acidity.

Consider the role of the halogen atom X in the molecule. A more electronegative halogen will pull electron density away from the rest of the molecule, potentially stabilizing the negative charge on the conjugate base after the acid donates a proton.

Recall that the stability of the conjugate base is a key factor in determining the strength of an acid. A more stable conjugate base corresponds to a stronger acid.

Analyze how the increased electronegativity of X affects the stability of the conjugate base. If X is more electronegative, it can better stabilize the negative charge, making the conjugate base more stable.

Conclude that as the electronegativity of the halogen atom X increases, the acidity of the molecule is likely to increase due to the increased stability of the conjugate base.

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Key Concepts

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

Electronegativity

Electronegativity is a measure of an atom's ability to attract and hold onto electrons in a chemical bond. In the context of halogens, as electronegativity increases, the atom's ability to stabilize negative charge also increases, which can influence the acidity of the molecule. Higher electronegativity typically leads to stronger bonds with hydrogen, affecting the molecule's tendency to donate protons.

Acidity

Acidity refers to the ability of a substance to donate protons (H⁺ ions) in a solution. The strength of an acid is often determined by the stability of the conjugate base formed after the proton is lost. In the case of halogen-containing acids, the more electronegative the halogen, the more stable the conjugate base, which generally results in increased acidity.

Conjugate Base Stability

The stability of a conjugate base is crucial in determining the strength of an acid. A more stable conjugate base is less likely to re-accept a proton, thus favoring the dissociation of the acid. In halogen acids, as the electronegativity of the halogen increases, the conjugate base becomes more stable due to the effective delocalization of negative charge, leading to increased acidity.

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Textbook Question

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Textbook Question

Consider the molecular models shown here, where X represents a halogen atom. (a) If X is the same atom in both molecules, which molecule will be more acidic?

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Textbook Question

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