Molar MassMolar mass of calcium fluoride (CaF2)
The molar mass of calcium fluoride, CaF2, is 78.07 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 78.07 grams.
78.07 g/mol
40.078 + 2 × 18.998 = 78.074 · 3 atoms in the formula · also called fluorite, fluorspar
About calcium fluoride
Calcium fluoride is the mineral fluorite, the main source of fluorine and hydrofluoric acid. Its crystals glow under ultraviolet light, the effect that gave fluorescence its name.
Other names: fluorite, fluorspar.
The working
The formula CaF2 has 1 calcium atom and 2 fluorine 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 |
|---|---|---|---|---|
| Calcium (Ca) | 1 | 40.078 | 40.078 | 51.33% |
| Fluorine (F) | 2 | 18.998 | 37.996 | 48.67% |
40.078 + 2 × 18.998 = 78.074 g/mol
With the rounded atomic masses used in many school books (Ca = 40, F = 19) the answer is 78 g/mol. The difference from 78.07 is too small to matter in most school sums.
Percentage composition
By mass, CaF2 is 51.33% calcium and 48.67% fluorine. The largest share comes from calcium. In a 100 g sample there are 51.3 g of calcium and 48.7 g of fluorine.
Notice that fluorine has more atoms in the formula (2) than calcium (1), yet gives a smaller share of the mass. Percentage by mass depends on how heavy each atom is, not only on how many there are.
Worked examples
Grams to moles. How many moles are in 10 g of CaF2? Divide the mass by the molar mass: 10 ÷ 78.07 = 0.1281 mol.
Moles to grams. What is the mass of 1.5 mol of CaF2? Multiply: 1.5 × 78.07 = 117.1 g.
Counting particles. 10 g contains 0.1281 mol × 6.022 × 1023 = 7.713 × 1022 formula units.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 7.807 g |
| 0.5 mol | 39.04 g |
| 1 mol | 78.07 g |
| 2 mol | 156.1 g |
| 5 mol | 390.4 g |
| Mass | Moles |
|---|---|
| 1 g | 0.01281 mol |
| 10 g | 0.1281 mol |
| 100 g | 1.281 mol |
| 1 kg | 12.81 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of CaF2?
The molar mass of calcium fluoride (CaF2) is 78.07 g/mol, or 78.074 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of CaF2?
100 ÷ 78.07 = 1.281 mol.
What is the mass of one formula unit of CaF2?
Divide the molar mass by the Avogadro constant: 78.07 ÷ 6.022 × 1023 = 1.296 × 10-22 g.
What is the percentage of calcium in CaF2?
Calcium makes up 51.33% of the mass of CaF2: 1 × 40.078 ÷ 78.074 × 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.