H₂SO₄ Molar Mass
Sulfuric acid
The molar mass of H₂SO₄ (sulfuric acid) is approximately 98.08 g/mol. Its chemical formula contains two hydrogen atoms, one sulfur atom, and four oxygen atoms — seven atoms in total. Using H = 1.008, S = 32.06, and O = 15.999, the calculated sum is 98.072 g/mol; 98.08 g/mol is a common reference value based on a different atomic-weight convention.
Molar mass of H₂SO₄
98.08 g/mol
Atomic-weight sum before rounding: 98.072 g/mol
| Formula | H₂SO₄ |
|---|---|
| Molar Mass | 98.08 g/mol |
| Molecular Weight | 98.072 |
| Hydrogen Atoms | 2 |
| Sulfur Atoms | 1 |
| Oxygen Atoms | 4 |
| Total Atoms | 7 |
Good to know
The listed atomic weights sum to 98.072 g/mol. The common 98.08 g/mol reference value uses a different atomic-weight convention, so the two values should not be treated as one number rounded in different ways.
How to Calculate the Molar Mass of H₂SO₄
Calculate the molar mass of H₂SO₄ by multiplying each atomic weight by its subscript, then adding the three contributions. Using H = 1.008, S = 32.06, and O = 15.999 gives 98.072 g/mol; the commonly quoted reference value of about 98.08 g/mol uses a different atomic-weight convention, rather than rounding this same total.
H₂SO₄
- Hydrogen: 2 × 1.008 = 2.016
- Sulfur: 1 × 32.06 = 32.06
- Oxygen: 4 × 15.999 = 63.996
2.016 + 32.06 + 63.996 = 98.072 g/mol
≈ 98.08 g/mol
Step 1 Count the atoms in H₂SO₄
H₂SO₄ contains 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms, for 7 atoms in each molecule.
Step 2 Find the atomic weights
Use H = 1.008, S = 32.06, and O = 15.999.
Step 3 Multiply each weight by its atom count
Hydrogen: 2 × 1.008 = 2.016; sulfur: 1 × 32.06 = 32.06; oxygen: 4 × 15.999 = 63.996.
Step 4 Add the contributions
2.016 + 32.06 + 63.996 = 98.072 g/mol. This is 98.07 g/mol to two decimal places using these weights. Other reference atomic-weight tables use a different atomic-weight convention and give approximately 98.08 g/mol, so 98.08 is not the rounded form of this 98.072 result.
Elemental Composition of H₂SO₄
Each element's share of the total mass of one mole of H₂SO₄. One mole — about 98.08 g — contains 2.016 g of hydrogen, 32.06 g of sulfur and 63.996 g of oxygen, and every sample scales by the same ratio. Stated as percent composition, H₂SO₄ is 2.06% hydrogen, 32.69% sulfur and 65.25% oxygen by mass.
| Element | Atoms | Atomic Weight | Mass Contribution | Mass % |
|---|---|---|---|---|
| Hydrogen (H) | 2 | 1.008 | 2.016 | 2.06% |
| Sulfur (S) | 1 | 32.06 | 32.06 | 32.69% |
| Oxygen (O) | 4 | 15.999 | 63.996 | 65.25% |
| Total | 7 | 98.072 | 100% |
What Is the Molecular Weight of H₂SO₄?
Molar mass is the mass of one mole of H₂SO₄ molecules, expressed in grams per mole (g/mol). Molecular mass is the mass of one H₂SO₄ molecule, expressed in unified atomic mass units (u, also called Da). Relative molecular mass compares a molecule’s mass with 1/12 of a carbon-12 atom and has no unit.
The corresponding numbers are the same when the same atomic-weight table is used: H = 1.008, S = 32.06, and O = 15.999 give about 98.072 u for one H₂SO₄ molecule and 98.072 g/mol for one mole. Common reference tables often report about 98.08 u and 98.08 g/mol instead. The small difference comes from the atomic-weight convention and retained precision, not from a difference between molecular mass and molar mass.
| Molar mass | 98.08 g/mol — the mass of one mole of H₂SO₄ molecules |
|---|---|
| Molecular mass | ≈ 98.072 u (Da) — the mass of one single H₂SO₄ molecule |
How Many Grams Are in One Mole of H₂SO₄?
One mole of pure H₂SO₄ has a mass of approximately 98.08 grams using the common reference value. The molar mass is the conversion factor: m = n × M, and n = m ÷ M. For example, 0.1 mol is 9.808 g, 0.5 mol is 49.04 g, 1 mol is 98.08 g, and 2 mol is 196.16 g. For sulfuric-acid solutions, first find the mass of pure H₂SO₄: 100 g of a 98% by-mass solution contains 98 g of H₂SO₄, or about 0.999 mol using 98.08 g/mol. Edit either value below to convert in either direction.
1 mol of H₂SO₄ has a mass of 98.08 g
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H₂SO₄ Formula Breakdown
H₂SO₄
- H = Hydrogen × 2
- S = Sulfur × 1
- O = Oxygen × 4
- Total atoms = 7
The subscript ₂ applies only to hydrogen and the subscript ₄ applies only to oxygen; sulfur has an implied subscript of 1. A coefficient written before the formula, such as 2H₂SO₄, counts separate molecules and does not change the molar mass of one H₂SO₄ molecule. For example, in H₂SO₄ + 2NaOH → Na₂SO₄ + 2H₂O, the coefficient 1 on H₂SO₄ means one mole of sulfuric acid; use the Chemical Equation Balancer to check the reaction coefficients. The 98.08 g/mol value describes pure H₂SO₄, not a sulfuric-acid solution that also contains water.
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Frequently Asked Questions
What is the molar mass of H₂SO₄?
About 98.08 g/mol. H₂SO₄ is sulfuric acid. H = 1.008, S = 32.06, and O = 15.999 sum to 98.072 g/mol, while common reference tables often report approximately 98.08 g/mol using a different atomic-weight convention.
How do you calculate the molar mass of H₂SO₄?
Add the atomic-mass contributions for 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms: 2 × 1.008 + 1 × 32.06 + 4 × 15.999 = 98.072 g/mol using H = 1.008, S = 32.06, and O = 15.999.
Why is the molar mass of H₂SO₄ sometimes 98.07 and sometimes 98.08?
The difference comes from the atomic-weight table and precision used. H = 1.008, S = 32.06, and O = 15.999 sum to 98.072 g/mol, which is 98.07 g/mol to two decimal places. Tables using another standard convention commonly give approximately 98.08 g/mol; it is not simply a different rounding of 98.072.
What is the molecular weight of sulfuric acid?
The relative molecular mass (often called molecular weight) of sulfuric acid is about 98.08 and has no unit. Its molecular mass is about 98.08 u (Da) per H₂SO₄ molecule, and its molar mass is 98.08 g/mol per mole when the same reference atomic weights are used.
How many atoms are in H₂SO₄?
Seven atoms: 2 hydrogen atoms, 1 sulfur atom, and 4 oxygen atoms in each H₂SO₄ molecule.
How many grams are in 1 mole of H₂SO₄?
About 98.08 grams using the common reference value. For a sample of sulfuric-acid solution, first determine the mass of pure H₂SO₄ because the solution also contains water.
Atomic weight reference
Calculations use the rounded standard atomic weights shown in the breakdown, not exact isotope masses. Natural isotope composition can vary, and some standard atomic weights are reported as intervals. See the CIAAW standard atomic weights for the reference values. Use your course’s table when its rounding differs.