Account for each of the following observations.
(a) H₂SO₄ is a stronger acid than H₂SO₃.

Verified step by step guidance

1. Understand the concept of acid strength: Acid strength is determined by the ability of an acid to donate protons (H+ ions) in solution. A stronger acid will dissociate more completely in water, releasing more H+ ions.
2. Compare the structures of H2SO4 and H2SO3: H2SO4 (sulfuric acid) has two hydroxyl groups (OH) and two double-bonded oxygens, while H2SO3 (sulfurous acid) has two hydroxyl groups and one double-bonded oxygen.
3. Consider the role of electronegativity and resonance: The presence of more electronegative oxygen atoms in H2SO4 allows for greater stabilization of the negative charge on the conjugate base (HSO4-) through resonance, compared to H2SO3.
4. Evaluate the stability of the conjugate bases: The conjugate base of H2SO4 (HSO4-) is more stable than the conjugate base of H2SO3 (HSO3-) due to the additional resonance stabilization provided by the extra oxygen atom in H2SO4.
5. Conclude based on the stability of conjugate bases: Since H2SO4 has a more stable conjugate base than H2SO3, it is a stronger acid, as the stability of the conjugate base is a key factor in determining acid strength.

Key Concepts

Acid Strength

Acid strength refers to the ability of an acid to donate protons (H⁺ ions) in a solution. Stronger acids dissociate more completely in water, leading to a higher concentration of H⁺ ions. The strength of an acid is influenced by its molecular structure, including the stability of its conjugate base after proton donation.

Conjugate Base Stability

The stability of a conjugate base is crucial in determining the strength of its corresponding acid. A more stable conjugate base results from factors such as resonance, electronegativity, and size of the atoms involved. In the case of H₂SO₄ and H₂SO₃, the conjugate base of H₂SO₄ (HSO₄⁻) is more stable than that of H₂SO₃ (HSO₃⁻), making H₂SO₄ a stronger acid.

Oxidation State and Acidic Behavior

The oxidation state of the central atom in an acid can influence its acidic behavior. In H₂SO₄, sulfur is in a higher oxidation state (+6) compared to H₂SO₃ (+4). Higher oxidation states typically lead to stronger acids due to increased positive charge on the central atom, which stabilizes the negative charge on the conjugate base after proton donation.