Molar MassMolar mass of sodium fluoride (NaF)
The molar mass of sodium fluoride, NaF, is 41.99 g/mol. One mole of it, which is 6.022 × 1023 formula units, has a mass of 41.99 grams.
About sodium fluoride
Sodium fluoride is the source of fluoride in many toothpastes and in fluoridated water. It is a simple one to one ionic salt of two light elements.
The working
The formula NaF has 1 sodium atom and 1 fluorine atom, 2 atoms in all. Multiply each count by the atomic weight of the element and add:
| Element | Atoms | Atomic weight | Total | Share by mass |
|---|---|---|---|---|
| Sodium (Na) | 1 | 22.990 | 22.990 | 54.75% |
| Fluorine (F) | 1 | 18.998 | 18.998 | 45.25% |
22.990 + 18.998 = 41.988 g/mol
With the rounded atomic masses used in many school books (Na = 23, F = 19) the answer is 42 g/mol. The difference from 41.99 is too small to matter in most school sums.
Percentage composition
By mass, NaF is 54.75% sodium and 45.25% fluorine. The largest share comes from sodium. In a 100 g sample there are 54.8 g of sodium and 45.2 g of fluorine.
Worked examples
Grams to moles. How many moles are in 250 g of NaF? Divide the mass by the molar mass: 250 ÷ 41.99 = 5.954 mol.
Moles to grams. What is the mass of 0.2 mol of NaF? Multiply: 0.2 × 41.99 = 8.398 g.
Counting particles. 250 g contains 5.954 mol × 6.022 × 1023 = 3.586 × 1024 formula units.
Making a solution. A 0.1 mol/L solution contains 0.1 × 41.99 = 4.199 g of NaF in each litre. For 250 mL, weigh 1.05 g and make it up to the mark with water.
Quick conversion tables
| Amount | Mass |
|---|---|
| 0.1 mol | 4.199 g |
| 0.5 mol | 20.99 g |
| 1 mol | 41.99 g |
| 2 mol | 83.98 g |
| 5 mol | 209.9 g |
| Mass | Moles |
|---|---|
| 1 g | 0.02382 mol |
| 10 g | 0.2382 mol |
| 100 g | 2.382 mol |
| 1 kg | 23.82 mol |
For other amounts use the grams and moles converter.
Questions people ask
What is the molar mass of NaF?
The molar mass of sodium fluoride (NaF) is 41.99 g/mol, or 41.988 g/mol before rounding, using IUPAC abridged atomic weights.
How many moles are in 100 g of NaF?
100 ÷ 41.99 = 2.382 mol.
What is the mass of one formula unit of NaF?
Divide the molar mass by the Avogadro constant: 41.99 ÷ 6.022 × 1023 = 6.972 × 10-23 g.
What is the percentage of sodium in NaF?
Sodium makes up 54.75% of the mass of NaF: 1 × 22.990 ÷ 41.988 × 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.