Molar MassMolar mass of sulphuric acid (H2SO4)
The molar mass of sulphuric acid, H2SO4, is 98.07 g/mol. One mole of it, which is 6.022 × 1023 molecules, has a mass of 98.07 grams.
98.07 g/mol
2 × 1.0080 + 32.06 + 4 × 15.999 = 98.072 · 7 atoms in the formula · also called sulfuric acid, oil of vitriol
About sulphuric acid
Sulphuric acid is a dense, oily liquid and one of the most produced chemicals in the world. It is used to make fertilisers, in lead-acid batteries and in refining. Each molecule can give two hydrogen ions, which is why 1 mole of it neutralises 2 moles of sodium hydroxide.
Other names: sulfuric acid, oil of vitriol.
The working
The formula H2SO4 has 2 hydrogen atoms, 1 sulphur atom and 4 oxygen atoms, 7 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Hydrogen (H) | 2 | 1.0080 | 2.016 | 2.06% |
| Sulphur (S) | 1 | 32.06 | 32.060 | 32.69% |
| Oxygen (O) | 4 | 15.999 | 63.996 | 65.25% |
2 × 1.0080 + 32.06 + 4 × 15.999 = 98.072 g/mol
With the rounded atomic masses used in many school books (H = 1, S = 32, O = 16) the answer is 98 g/mol. The difference from 98.07 is too small to matter in most school sums.
Percentage composition
By mass, H2SO4 is 2.06% hydrogen, 32.69% sulphur and 65.25% oxygen. The largest share comes from oxygen. In a 100 g sample there are 2.1 g of hydrogen, 32.7 g of sulphur and 65.3 g of oxygen.
Worked examples
Grams to moles. How many moles are in 10 g of H2SO4? Divide the mass by the molar mass: 10 ÷ 98.07 = 0.102 mol.
Moles to grams. What is the mass of 1.5 mol of H2SO4? Multiply: 1.5 × 98.07 = 147.1 g.
Counting particles. 10 g contains 0.102 mol × 6.022 × 1023 = 6.141 × 1022 molecules, and 4.298 × 1023 atoms in all.
Making a solution. A 0.1 mol/L solution contains 0.1 × 98.07 = 9.807 g of H2SO4 in each litre. For 250 mL, weigh 2.452 g and make it up to the mark with water.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 9.807 g |
| 0.5 mol | 49.04 g |
| 1 mol | 98.07 g |
| 2 mol | 196.1 g |
| 5 mol | 490.4 g |
| Mass | Moles |
|---|---|
| 1 g | 0.0102 mol |
| 10 g | 0.102 mol |
| 100 g | 1.02 mol |
| 1 kg | 10.2 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of H2SO4?
The molar mass of sulphuric acid (H2SO4) is 98.07 g/mol, or 98.072 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of H2SO4?
100 ÷ 98.07 = 1.02 mol.
What is the mass of one molecule of H2SO4?
Divide the molar mass by the Avogadro constant: 98.07 ÷ 6.022 × 1023 = 1.629 × 10-22 g.
What is the percentage of oxygen in H2SO4?
Oxygen makes up 65.25% of the mass of H2SO4: 4 × 15.999 ÷ 98.072 × 100.
Which values? This site uses the abridged standard atomic weights published by IUPAC (CIAAW), read on 12 November 2026. Your textbook or question paper may round them differently, for example H = 1 and O = 16, so its answer can differ slightly. In an exam, use the values the paper gives.