CaCl₂ Molar Mass
Calcium chloride (anhydrous)
The molar mass of anhydrous calcium chloride (CaCl₂) is approximately 110.98 g/mol. Each formula unit contains one calcium atom and two chlorine atoms. Using Ca = 40.078 and Cl = 35.45 gives 40.078 + 2 × 35.45 = 110.978 g/mol — about 36.11% calcium and 63.89% chlorine by mass. Because CaCl₂ is an ionic compound, this same number is properly called the formula mass.
Molar mass of CaCl₂
110.98 g/mol
Atomic-weight sum before rounding: 110.978 g/mol
| Formula | CaCl₂ |
|---|---|
| Molar Mass | 110.98 g/mol |
| Formula Mass | ≈ 110.978 u |
| Calcium Atoms | 1 |
| Chlorine Atoms | 2 |
| Ion Ratio | 1 : 2 |
| Atoms per Formula Unit | 3 |
Good to know
This result is for anhydrous CaCl₂ — calcium chloride without water of crystallization. Common hydrates such as CaCl₂·2H₂O and CaCl₂·6H₂O have higher molar masses because the waters of hydration add mass.
How to Calculate the Molar Mass of CaCl₂
The calcium chloride molar mass is the sum of one calcium atomic weight and two chlorine atomic weights. Using Ca = 40.078 and Cl = 35.45 gives approximately 110.978 g/mol — commonly rounded to 110.98 g/mol. The same number also goes by "formula mass of calcium chloride", because CaCl₂ is an ionic compound counted in formula units rather than discrete molecules.
CaCl₂
- Calcium: 1 × 40.078 = 40.078
- Chlorine: 2 × 35.45 = 70.9
40.078 + 70.9 = 110.978 g/mol
≈ 110.98 g/mol
Step 1 Read the chemical formula
CaCl₂ contains 1 calcium atom and 2 chlorine atoms. Subscripts count atoms, and a symbol without a subscript counts one.
Step 2 Find the atomic masses
Use the listed, rounded standard atomic weights: Ca = 40.078 and Cl = 35.45. Most atomic weights are not whole numbers — each one averages an element's naturally occurring isotopes.
Step 3 Multiply by the atom counts
Each element contributes its atomic weight once per atom: Ca: 1 × 40.078 = 40.078; Cl: 2 × 35.45 = 70.9.
Step 4 Add the contributions
40.078 + 70.9 = 110.978 g/mol. The total using these atomic weights is approximately 110.978 g/mol, usually reported as 110.98 g/mol. One mole of CaCl₂ — 6.022 × 10²³ formula units, 3 atoms each — has approximately this mass in grams.
CaCl₂ Formula Breakdown
CaCl₂
- Ca = Calcium × 1
- Cl = Chlorine × 2
- Total atoms = 3
The subscript ₂ applies only to chlorine — calcium keeps its implied subscript of 1. Coefficients written in front of a formula (the 2 in 2CaCl₂) count separate formula units and do not change the unit itself.
Elemental Composition of CaCl₂
Each element's share of the total mass of one mole of CaCl₂. One mole — about 110.98 g — contains 40.078 g of calcium and 70.9 g of chlorine, and every sample scales by the same ratio. Stated as percent composition, CaCl₂ is 36.11% calcium and 63.89% chlorine by mass.
| Element | Atoms | Atomic Weight | Mass Contribution | Mass % |
|---|---|---|---|---|
| Calcium (Ca) | 1 | 40.078 | 40.078 | 36.11% |
| Chlorine (Cl) | 2 | 35.45 | 70.9 | 63.89% |
| Total | 3 | 110.978 | 100% |
What Is the Formula Mass of CaCl₂?
The formula mass of CaCl₂ is approximately 110.98 u per formula unit — numerically the same number as the molar mass, 110.98 g/mol, because one mole of formula units weighs as many grams as one formula unit weighs in unified atomic mass units. A formula unit is the smallest electrically neutral bundle: one Ca²⁺ ion paired with two Cl⁻ ions in a 1 : 2 ratio. Solid calcium chloride is a crystal lattice of those ions, so there is no isolated "CaCl₂ molecule" — the formula unit is the counting unit that plays the molecule's role.
Textbooks and homework may still say "molecular weight of CaCl₂" or "molecular mass of CaCl₂". Those phrases are informal and still mean 110.98 — the more precise terms are formula mass and formula weight. Tables that list 110.98 or 110.984 are using the same quantity with slightly different chlorine rounding; with Ca = 40.078 and Cl = 35.45 the sum is 110.978, which rounds to 110.98 g/mol.
| Molar mass | 110.98 g/mol — the mass of one mole of CaCl₂ formula units |
|---|---|
| Formula mass | ≈ 110.978 u (Da) — the mass of one single CaCl₂ formula unit |
What Is the Chemical Formula for Calcium Chloride?
The chemical formula for anhydrous calcium chloride is CaCl₂. The compound is built from ions, not neutral atoms: each calcium atom loses two electrons to become a Ca²⁺ ion, and each chlorine atom gains one electron to become a Cl⁻ ion.
Ca²⁺ carries a +2 charge and Cl⁻ carries a −1 charge, so two chloride ions are needed to cancel one calcium ion: Ca²⁺ + 2Cl⁻ → CaCl₂. The ion ratio is therefore 1 : 2 — one Ca²⁺ for every two Cl⁻ — which is why the formula carries the subscript ₂ on chlorine and none on calcium. Ionic formulas report that simplest whole-number ratio of ions, the formula unit, rather than a count of atoms bonded into a molecule.
How Many Grams Are in One Mole of CaCl₂?
One mole of anhydrous CaCl₂ has a mass of approximately 110.98 grams. That is the whole conversion — the molar mass is the conversion factor between moles and grams. 0.5 mol × 110.98 g/mol = 55.49 g, 1 mol = 110.98 g, and 2 mol = 221.96 g. Going the other way, divide by the same factor: 55.49 g of anhydrous CaCl₂ is 55.49 ÷ 110.98 ≈ 0.5 mol. Enter an amount below to convert either way, using 110.98 g/mol.
1 mol of CaCl₂ has a mass of 110.98 g
Convert grams ↔ moles of CaCl₂ in the full calculator →
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Anhydrous vs Hydrated Calcium Chloride
110.98 g/mol is for anhydrous CaCl₂ only. Calcium chloride also forms hydrates that lock water molecules into the crystal; each water of crystallization adds the molar mass of H₂O (18.015 g/mol) and changes the elemental mass percentages. Use the anhydrous mass only when the label says anhydrous — otherwise match the hydrate formula on the bottle.
The hydrate masses follow directly from the anhydrous total: 110.978 + 2 × 18.015 = 147.008 g/mol for the dihydrate, and 110.978 + 6 × 18.015 = 219.068 g/mol for the hexahydrate.
| Formula | Name | Molar mass |
|---|---|---|
| CaCl₂ | Anhydrous | 110.978 g/mol |
| CaCl₂·2H₂O | Dihydrate | 147.008 g/mol |
| CaCl₂·6H₂O | Hexahydrate | 219.068 g/mol |
Need a hydrate mass instead? Open the molar mass calculator for CaCl₂·6H₂O, or change the water count there for another hydrate.
CaCl₂ Molar Mass Units and Conversions
Molar mass is normally quoted in grams per mole (g/mol), because lab-scale amounts are measured in grams and moles. The same number scales across units: 110.98 g/mol = 110,980 mg/mol = 0.11098 kg/mol. Per formula unit, the same value appears in unified atomic mass units — one CaCl₂ formula unit has a formula mass of about 110.98 u. The number never changes; only the unit — and the amount of CaCl₂ it describes — does.
CaCl₂ molar mass in every unit
- grams per mole: 110.98 g/mol
- milligrams per mole: 110,980 mg/mol
- kilograms per mole: 0.11098 kg/mol
- per formula unit: ≈ 110.978 u
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Frequently Asked Questions
What is the molar mass of CaCl2?
Approximately 110.98 g/mol for anhydrous calcium chloride. Using the listed atomic weights, 1 × 40.078 (calcium) + 2 × 35.45 (chlorine) = 110.978 g/mol, which rounds to 110.98 g/mol. Because CaCl₂ is ionic, the same number is also called the formula mass.
How do you calculate the molar mass of CaCl2?
Add one calcium atomic mass to two chlorine atomic masses: 40.078 + (2 × 35.45) = 40.078 + 70.9 = 110.978 ≈ 110.98 g/mol. In general: read the subscripts in the formula, multiply each element's atomic weight by its atom count, then add the contributions.
What is the formula mass of CaCl2?
Approximately 110.98 u per formula unit. One formula unit is one Ca²⁺ ion paired with two Cl⁻ ions in a 1 : 2 ratio; numerically, formula mass in u and molar mass in g/mol are the same number.
How many grams are in one mole of CaCl2?
About 110.98 grams of anhydrous CaCl₂. One mole contains 6.022 × 10²³ formula units, and the molar mass converts that amount directly to mass: 1 mol × 110.98 g/mol = 110.98 g.
What is the chemical formula for calcium chloride?
CaCl₂ for the anhydrous salt. Each Ca²⁺ ion balances two Cl⁻ ions, so the charges cancel in a 1 : 2 ratio and the formula carries the subscript ₂ on chlorine.
How many chlorine atoms are in CaCl2?
Two chlorine atoms (as two Cl⁻ ions) in every formula unit, together with one calcium atom.
Is the molar mass of CaCl2 different from CaCl2·2H2O?
Yes. Anhydrous CaCl₂ is about 110.978 g/mol; the dihydrate CaCl₂·2H₂O is about 147.008 g/mol because two waters of crystallization add 2 × 18.015 g/mol.
What is the molar mass of CaCl2·6H2O?
About 219.07 g/mol (219.068 g/mol before rounding). Six waters of crystallization add 6 × 18.015 = 108.090 g/mol to the anhydrous 110.978 g/mol total.
Atomic weight reference
Calculations use the rounded standard atomic weights shown in the breakdown, not exact isotope masses. Natural isotope composition can vary, and some standard atomic weights are reported as intervals. See the CIAAW standard atomic weights for the reference values. Use your course’s table when its rounding differs.