Molar MassMolar mass of lead(II) oxide (PbO)
The molar mass of lead(II) oxide, PbO, is 223.20 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 223.20 grams.
223.20 g/mol
207.2 + 15.999 = 223.199 · 2 atoms in the formula · also called litharge
About lead(II) oxide
Lead(II) oxide is a yellow or reddish solid used in lead glass and in lead-acid battery plates.
Other names: litharge.
The working
The formula PbO has 1 lead atom and 1 oxygen atom, 2 atoms in all. Multiply each count by the atomic weight of the element and add:
207.2 + 15.999 = 223.199 g/mol
With the rounded atomic masses used in many school books (Pb = 207, O = 16) the answer is 223 g/mol. The difference from 223.20 is too small to matter in most school sums.
Percentage composition
By mass, PbO is 92.83% lead and 7.17% oxygen. The largest share comes from lead. In a 100 g sample there are 92.8 g of lead and 7.2 g of oxygen.
Worked examples
Grams to moles. How many moles are in 40 g of PbO? Divide the mass by the molar mass: 40 ÷ 223.20 = 0.1792 mol.
Moles to grams. What is the mass of 3 mol of PbO? Multiply: 3 × 223.20 = 669.6 g.
Counting particles. 40 g contains 0.1792 mol × 6.022 × 1023 = 1.079 × 1023 formula units.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 22.32 g |
| 0.5 mol | 111.6 g |
| 1 mol | 223.2 g |
| 2 mol | 446.4 g |
| 5 mol | 1116 g |
| Mass | Moles |
|---|---|
| 1 g | 0.00448 mol |
| 10 g | 0.0448 mol |
| 100 g | 0.448 mol |
| 1 kg | 4.48 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of PbO?
The molar mass of lead(II) oxide (PbO) is 223.20 g/mol, or 223.199 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of PbO?
100 ÷ 223.20 = 0.448 mol.
What is the mass of one formula unit of PbO?
Divide the molar mass by the Avogadro constant: 223.20 ÷ 6.022 × 1023 = 3.706 × 10-22 g.
What is the percentage of lead in PbO?
Lead makes up 92.83% of the mass of PbO: 1 × 207.2 ÷ 223.199 × 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.