Molar MassMolar mass of zinc chloride (ZnCl2)
The molar mass of zinc chloride, ZnCl2, is 136.28 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 136.28 grams.
About zinc chloride
Zinc chloride is a white salt that takes up water readily. It is used as a flux for soldering and in dry cells. It can be made by dissolving zinc in hydrochloric acid, a reaction often used to prepare hydrogen.
The working
The formula ZnCl2 has 1 zinc atom and 2 chlorine atoms, 3 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Zinc (Zn) | 1 | 65.38 | 65.380 | 47.97% |
| Chlorine (Cl) | 2 | 35.45 | 70.900 | 52.03% |
65.38 + 2 × 35.45 = 136.280 g/mol
With the rounded atomic masses used in many school books (Zn = 65, Cl = 35.5) the answer is 136 g/mol. The difference from 136.28 is too small to matter in most school sums.
Percentage composition
By mass, ZnCl2 is 47.97% zinc and 52.03% chlorine. The largest share comes from chlorine. In a 100 g sample there are 48.0 g of zinc and 52.0 g of chlorine.
Worked examples
Grams to moles. How many moles are in 250 g of ZnCl2? Divide the mass by the molar mass: 250 ÷ 136.28 = 1.834 mol.
Moles to grams. What is the mass of 0.2 mol of ZnCl2? Multiply: 0.2 × 136.28 = 27.26 g.
Counting particles. 250 g contains 1.834 mol × 6.022 × 1023 = 1.105 × 1024 formula units.
Making a solution. A 0.1 mol/L solution contains 0.1 × 136.28 = 13.63 g of ZnCl2 in each litre. For 250 mL, weigh 3.407 g and make it up to the mark with water.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 13.63 g |
| 0.5 mol | 68.14 g |
| 1 mol | 136.3 g |
| 2 mol | 272.6 g |
| 5 mol | 681.4 g |
| Mass | Moles |
|---|---|
| 1 g | 0.007338 mol |
| 10 g | 0.07338 mol |
| 100 g | 0.7338 mol |
| 1 kg | 7.338 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of ZnCl2?
The molar mass of zinc chloride (ZnCl2) is 136.28 g/mol, or 136.280 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of ZnCl2?
100 ÷ 136.28 = 0.7338 mol.
What is the mass of one formula unit of ZnCl2?
Divide the molar mass by the Avogadro constant: 136.28 ÷ 6.022 × 1023 = 2.263 × 10-22 g.
What is the percentage of chlorine in ZnCl2?
Chlorine makes up 52.03% of the mass of ZnCl2: 2 × 35.45 ÷ 136.280 × 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.