Molar mass of zinc chloride (ZnCl₂)
The molar mass of zinc chloride (ZnCl₂) is 136.28 g/mol, summed from the IUPAC standard atomic weights of Zn, Cl x 2.
- Moles in the sample mass
- 0.073 378 339 mol
- Mass of that amount of substance
- 136.28
- Molecules in the sample mass
- 4.41895e+22
Show the working
- Mass of sample = 10
- Amount of substance = 1
- Molar mass = 65.38 + 35.45*2 = 136.28
- Moles in the sample mass = 10 / 136.28 = 0.073 378 3
- Mass of that amount of substance = 1 * 136.28 = 136.28
- Molecules in the sample mass = 0.073 378 3 * NA = 4.41895e+22
Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.
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The formula
- Molar mass = sum over elements of (atomic weight x number of atoms)
- For ZnCl₂: 65.38 + 35.45 x 2 = 136.28 g/mol
- Moles = mass / molar mass; mass = moles x molar mass
- Molecules = moles x 6.02214076 x 10^23 (the Avogadro constant, exact by definition)
Molar mass in grams per mole is numerically equal to the molecular mass in daltons, so this figure doubles as the molecular weight.
Atomic weights are the IUPAC 2021 standard values. Several elements have a range rather than a single value because isotope ratios vary between sources; the conventional single value is used here.
Composition by mass
| Element | Atoms | Atomic weight | Contribution (g/mol) | Share of mass |
|---|---|---|---|---|
| Chlorine (Cl) | 2 | 35.45 | 70.9 | 52.025 % |
| Zinc (Zn) | 1 | 65.38 | 65.38 | 47.975 % |
Contributions add to the molar mass of 136.28 g/mol. Atomic weights are the IUPAC 2021 standard values.
Frequently asked
What is the molar mass of zinc chloride?
136.28 g/mol, for the formula ZnCl₂.
How do you convert grams of zinc chloride to moles?
Divide the mass in grams by 136.28 g/mol. One gram of zinc chloride is 0.00733783 mol.
How many grams are in one mole of zinc chloride?
136.28 g, by definition of the molar mass.
Is molar mass the same as molecular weight?
Numerically yes, for the purposes of this calculation. Molecular weight is a dimensionless ratio and molar mass carries units of g/mol, but the digits are identical.
Where the numbers come from
- IUPAC 2021 standard atomic weights; Avogadro constant fixed by the 2019 SI.