Molar MassMolar mass of lead(II) sulphate (PbSO4)
The molar mass of lead(II) sulphate, PbSO4, is 303.26 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 303.26 grams.
303.26 g/mol
207.2 + 32.06 + 4 × 15.999 = 303.256 · 6 atoms in the formula · also called lead sulfate
About lead(II) sulphate
Lead(II) sulphate is a white solid that is almost insoluble in water. It forms on both plates of a lead-acid battery as the battery discharges. Lead is so heavy that it gives about two thirds of the mass.
Other names: lead sulfate.
The working
The formula PbSO4 has 1 lead atom, 1 sulphur atom and 4 oxygen atoms, 6 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Lead (Pb) | 1 | 207.2 | 207.200 | 68.33% |
| Sulphur (S) | 1 | 32.06 | 32.060 | 10.57% |
| Oxygen (O) | 4 | 15.999 | 63.996 | 21.10% |
207.2 + 32.06 + 4 × 15.999 = 303.256 g/mol
With the rounded atomic masses used in many school books (Pb = 207, S = 32, O = 16) the answer is 303 g/mol. The difference from 303.26 is too small to matter in most school sums.
Percentage composition
By mass, PbSO4 is 68.33% lead, 10.57% sulphur and 21.10% oxygen. The largest share comes from lead. In a 100 g sample there are 68.3 g of lead, 10.6 g of sulphur and 21.1 g of oxygen.
Worked examples
Grams to moles. How many moles are in 5 g of PbSO4? Divide the mass by the molar mass: 5 ÷ 303.26 = 0.01649 mol.
Moles to grams. What is the mass of 0.25 mol of PbSO4? Multiply: 0.25 × 303.26 = 75.81 g.
Counting particles. 5 g contains 0.01649 mol × 6.022 × 1023 = 9.929 × 1021 formula units.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 30.33 g |
| 0.5 mol | 151.6 g |
| 1 mol | 303.3 g |
| 2 mol | 606.5 g |
| 5 mol | 1516 g |
| Mass | Moles |
|---|---|
| 1 g | 0.003298 mol |
| 10 g | 0.03298 mol |
| 100 g | 0.3298 mol |
| 1 kg | 3.298 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of PbSO4?
The molar mass of lead(II) sulphate (PbSO4) is 303.26 g/mol, or 303.256 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of PbSO4?
100 ÷ 303.26 = 0.3298 mol.
What is the mass of one formula unit of PbSO4?
Divide the molar mass by the Avogadro constant: 303.26 ÷ 6.022 × 1023 = 5.036 × 10-22 g.
What is the percentage of lead in PbSO4?
Lead makes up 68.33% of the mass of PbSO4: 1 × 207.2 ÷ 303.256 × 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.