H2SO4
Sulfuric acid (H2SO4)
Also known as: oil of vitriol, battery acid
Sulfuric acid is the world's most-produced industrial chemical — national economies have literally been gauged by their H₂SO₄ output. It is a strong diprotic acid: both hydrogens ionise in water. Concentrated sulfuric acid is also a fierce dehydrating agent, famously charring sugar into a column of carbon.
Molar mass breakdown
98.072 g/mol| Element | Atoms | Mass (g/mol) | % by mass |
|---|---|---|---|
| Oxygen (O) | 4 | 63.996 | 65.25% |
| Sulfur (S) | 1 | 32.06 | 32.69% |
| Hydrogen (H) | 2 | 2.016 | 2.056% |
What sulfuric acid is used for
- Fertiliser manufacturing (phosphates) — the biggest use
- Lead-acid car batteries (as ~35% solution)
- Metal processing, refining and chemical synthesis
- Drain cleaners (with extreme caution)
Key facts
- Molar mass ≈ 98.08 g/mol.
- Diprotic: one mole releases up to two moles of H⁺.
- Mixing with water is violently exothermic — always add acid to water, never the reverse.
Frequently asked questions
What is the molar mass of H2SO4?
About 98.08 g/mol: 2 × 1.008 + 32.06 + 4 × 15.999.
Why add acid to water and not water to acid?
Dilution releases intense heat. Adding water to concentrated acid can flash-boil the first drops and spatter acid; adding acid slowly to a large volume of water spreads the heat safely.
What does diprotic mean?
The molecule can donate two protons (H⁺ ions) — H₂SO₄ → HSO₄⁻ → SO₄²⁻.