Which compound does H2SO4 represent when in an aqueous solution? a) sulfur oxide b) sulfuric acid c) hydrogen sulfide d) hydrogen disulfate
The correct answer and explanation is:
Correct Answer: b) sulfuric acid
H₂SO₄ in aqueous solution represents sulfuric acid. Sulfuric acid is a strong mineral acid composed of two hydrogen atoms, one sulfur atom, and four oxygen atoms. Its molecular formula, H₂SO₄, shows that it contains two replaceable hydrogen ions, making it a diprotic acid. When dissolved in water, sulfuric acid ionizes completely in a two-step process. In the first step, it releases one hydrogen ion (H⁺) and forms the hydrogen sulfate ion (HSO₄⁻). In the second step, it can release another hydrogen ion, forming the sulfate ion (SO₄²⁻).
The reaction in water is:
H₂SO₄ → H⁺ + HSO₄⁻
HSO₄⁻ ⇌ H⁺ + SO₄²⁻
Sulfuric acid is widely used in industry and laboratories. It is involved in processes such as fertilizer production, battery acid for lead-acid batteries, and in the refining of petroleum. Its strong acidity and dehydrating nature make it a key reagent in many chemical reactions.
It is important to distinguish sulfuric acid from other compounds in the answer choices. Sulfur oxide refers to gases like SO₂ or SO₃, not a liquid acid. Hydrogen sulfide (H₂S) is a toxic gas that smells like rotten eggs and contains no oxygen. Hydrogen disulfate is a less common name, and it does not refer to H₂SO₄ but could confusingly describe HSO₄⁻ ions in some contexts.
Therefore, when H₂SO₄ is placed in water, it forms an acidic solution recognized as sulfuric acid. Its strong acidic properties and complete dissociation in water define its behavior as a strong acid, making the correct answer sulfuric acid.