What is the correct chemical formula for sulphuric acid, the strong dibasic acid of sulphur commonly used in industry and laboratories?

Introduction / Context:
This question focuses on sulphuric acid, one of the most important industrial chemicals. Knowing its correct chemical formula is essential for writing reactions, doing stoichiometric calculations and understanding acid base chemistry. Sulphuric acid is a strong dibasic acid of sulphur in oxidation state plus six and is widely used in batteries, fertiliser production and chemical manufacturing.

Given Data / Assumptions:

• We are asked for the formula of sulphuric acid.
• Sulphuric acid is a strong acid and dibasic, meaning it can donate two hydrogen ions.
• Options include H2SO4, H2SO3, H3SO3, H3SO4 and HSO4.
• We assume standard nomenclature used in school textbooks.

Concept / Approach:
Sulphuric acid is the higher oxidation state oxyacid of sulphur compared to sulphurous acid. In sulphuric acid, sulphur has oxidation state plus six and the acid formula is H2SO4. It contains two ionisable hydrogen atoms attached to oxygen, making it dibasic. Sulphurous acid, by contrast, has formula H2SO3 and sulphur in oxidation state plus four. Formulas with three hydrogens would correspond to a tribasic acid, which is not how sulphuric acid is defined at this level. The HSO4 form represents the hydrogen sulphate ion, not the neutral acid.

Step-by-Step Solution:
Step 1: Recall that sulphuric acid is written as H2SO4 in almost all chemical equations involving this acid. Step 2: It is dibasic, so it must contain two acidic hydrogen atoms, matching the two hydrogens in H2SO4. Step 3: Check oxidation state of sulphur in H2SO4: let sulphur be x, hydrogen is plus one and oxygen is minus two. Step 4: Write the equation for neutrality: 2*(+1) + x + 4*(-2) = 0, which gives 2 + x - 8 = 0, so x = +6. Step 5: This plus six oxidation state agrees with sulphuric acid. Step 6: H2SO3 would give sulphur oxidation state plus four and is known as sulphurous acid, not sulphuric acid. Step 7: H3SO3 and H3SO4 would indicate three acidic hydrogens and are not standard formulas for ordinary sulphur oxyacids taught at this level. Step 8: HSO4 is an anion, hydrogen sulphate, which carries a negative charge and is not the neutral acid. Step 9: Therefore, the correct formula of sulphuric acid is H2SO4.

Verification / Alternative check:
Industrial chemistry and laboratory safety materials consistently denote sulphuric acid as H2SO4. It is one of the most produced chemicals worldwide. When you balance equations involving acid base neutralisation or dehydration reactions using sulphuric acid, the formula H2SO4 is used. In contrast, H2SO3 appears only in contexts discussing the less stable sulphurous acid and is usually associated with sulphur dioxide in water. This widespread consistency confirms that H2SO4 is the only correct choice.

Why Other Options Are Wrong:
H2SO3 is sulphurous acid and corresponds to a different oxidation state and different properties. H3SO3 and H3SO4 do not match the typical dibasic nature of sulphuric acid and are not standard simple acids in introductory chemistry. HSO4 is an ion, not a neutral molecular acid. Therefore, these options cannot represent sulphuric acid as described in the question.

Common Pitfalls:
Students sometimes confuse sulphuric and sulphurous acid names due to their similar spelling. A simple memory aid is that sulphuric acid, with the ic ending, is the more oxidised form with more oxygen atoms, H2SO4. Sulphurous acid, with the ous ending, has fewer oxygen atoms, H2SO3. Associating sulphuric acid with strong acid behaviour and heavy industrial use can also help firmly fix H2SO4 in memory.

Final Answer:
The correct chemical formula of sulphuric acid is H2SO4.