Molar MassMolar mass of copper(II) sulphate (CuSO4)
The molar mass of copper(II) sulphate, CuSO4, is 159.60 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 159.60 grams.
159.60 g/mol
63.546 + 32.06 + 4 × 15.999 = 159.602 · 6 atoms in the formula · also called anhydrous copper sulfate
About copper(II) sulphate
Anhydrous copper(II) sulphate is a white powder. It turns blue when it takes up water, a change used as a test for water. The familiar blue crystals are the pentahydrate, which has a much larger molar mass.
Other names: anhydrous copper sulfate.
The working
The formula CuSO4 has 1 copper 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 |
|---|---|---|---|---|
| Copper (Cu) | 1 | 63.546 | 63.546 | 39.82% |
| Sulphur (S) | 1 | 32.06 | 32.060 | 20.09% |
| Oxygen (O) | 4 | 15.999 | 63.996 | 40.10% |
63.546 + 32.06 + 4 × 15.999 = 159.602 g/mol
With the rounded atomic masses used in many school books (Cu = 63.5, S = 32, O = 16) the answer is 159.5 g/mol. The difference from 159.60 is too small to matter in most school sums.
Percentage composition
By mass, CuSO4 is 39.82% copper, 20.09% sulphur and 40.10% oxygen. The largest share comes from oxygen. In a 100 g sample there are 39.8 g of copper, 20.1 g of sulphur and 40.1 g of oxygen.
Worked examples
Grams to moles. How many moles are in 10 g of CuSO4? Divide the mass by the molar mass: 10 ÷ 159.60 = 0.06266 mol.
Moles to grams. What is the mass of 1.5 mol of CuSO4? Multiply: 1.5 × 159.60 = 239.4 g.
Counting particles. 10 g contains 0.06266 mol × 6.022 × 1023 = 3.773 × 1022 formula units.
Making a solution. A 0.1 mol/L solution contains 0.1 × 159.60 = 15.96 g of CuSO4 in each litre. For 250 mL, weigh 3.99 g and make it up to the mark with water.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 15.96 g |
| 0.5 mol | 79.8 g |
| 1 mol | 159.6 g |
| 2 mol | 319.2 g |
| 5 mol | 798 g |
| Mass | Moles |
|---|---|
| 1 g | 0.006266 mol |
| 10 g | 0.06266 mol |
| 100 g | 0.6266 mol |
| 1 kg | 6.266 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of CuSO4?
The molar mass of copper(II) sulphate (CuSO4) is 159.60 g/mol, or 159.602 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of CuSO4?
100 ÷ 159.60 = 0.6266 mol.
What is the mass of one formula unit of CuSO4?
Divide the molar mass by the Avogadro constant: 159.60 ÷ 6.022 × 1023 = 2.650 × 10-22 g.
What is the percentage of oxygen in CuSO4?
Oxygen makes up 40.10% of the mass of CuSO4: 4 × 15.999 ÷ 159.602 × 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.