Moles to grams for propane is a multiplication by 44.097 g/mol. A mole weighs 44.097 g, 100 mmol weighs 4.4097 g, 10 mmol weighs 0.44097 g and a millimole is 44.097 mg. Those four figures cover most of what gets weighed out in practice, and the table below extends them from a micromole up to ten moles.
The figure comes from the formula. Propane is 3 × 12.011 (C) + 8 × 1.008 (H), which is 44.097 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Carbon makes up the largest share of the mass: 3 of the 11 atoms in a formula unit are carbon, and they account for 36.033 g of the 44.097 g, or 81.71% by mass. The derivation table below breaks the whole molecule down element by element.
Two habits make the weighed mass match the calculation. Weigh into a container you have tared rather than onto paper, because what stays behind on paper is a real loss — on a 100 mg weighing it is easily a percent. And when the target is under about 20 mg, weigh ten times that and dilute, since the absolute error of the balance does not shrink with the sample.
Bottled gas. The molar mass is what links a cylinder weight to the energy in it, which is how barbecue and heating cylinders are actually sold. At 44.097 g/mol it is heavier than 8 of the 11 gases and small molecules covered here, and that ranking matters more than it looks: carbon dioxide has a molar mass of 44.009 g/mol, so a gram of it contains 0.2% more formula units than a gram of propane. Weigh by mass and you are not weighing equal amounts of substance.
Because this is a gas, volume is often the easier measure. One mole of any ideal gas occupies 22.414 L at 0 °C and 1 atm and 24.4655 L at 25 °C, so 44.097 g of propane — one mole — fills about 24.47 litres at room temperature. Real gases depart from that by a percent or so, more near their boiling point, but for ordinary work the molar volume is the quickest route from grams to litres.
The formula
n- The amount of propane you need, in moles
44.097- The molar mass of propane in g/mol, derived from its formula
m- The mass to weigh out, in grams
How it works, step by step
- Enter the amount you need, in moles.
- It is multiplied by 44.097 g/mol.
- The result is the mass to weigh out, also given in milligrams.
- Weigh into a tared container; anything left in the boat is a real loss from the amount you calculated.
Worked examples
5 mmol of propane in grams
5 mmol × 44.097 g/mol = 0.220485 g, which is 220.485 mg. Doubling the amount doubles the mass to 0.44097 g, because the relationship is a plain proportion once the molar mass is fixed.
250 mmol of propane in grams
250 mmol × 44.097 g/mol = 11.0243 g, which is 11,024.2 mg. Doubling the amount doubles the mass to 22.0485 g, because the relationship is a plain proportion once the molar mass is fixed.
2 mol of propane in grams
2 mol × 44.097 g/mol = 88.194 g, which is 88,194 mg. Doubling the amount doubles the mass to 176.388 g, because the relationship is a plain proportion once the molar mass is fixed.
How to read your score
Frequently asked questions
What is the molar mass of propane (C3H8)?
It is 44.097 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 3 × 12.011 (C) + 8 × 1.008 (H). One mole of propane therefore weighs 44.097 g, and a gram of it is 22.677 mmol.
What percentage of propane is carbon?
81.71% by mass. Each formula unit contains 3 carbon atoms contributing 36.033 g of the 44.097 g total, so 100 g of propane contains 81.71 g of carbon and a kilogram contains 817.13 g of it.
How many grams is one mole of propane?
44.097 g, by definition of the molar mass. Two moles is 88.194 g and half a mole is 22.0485 g.
How many grams is 0.1 mol, and how many milligrams is 1 mmol?
0.1 mol of propane is 4.4097 g. One millimole is 44.097 mg and one micromole is 44.097 µg, which is the range most bench work sits in.
How do I weigh out an amount too small for my balance?
Weigh a larger mass and dilute it. To get 0.441 mg of propane, weigh 4.41 mg into 100 mL, then take 10 mL of that: the absolute error of the balance stays the same while the amount delivered falls by a factor of ten.
Should I use the hydrate or the anhydrous molar mass?
This page is the anhydrous form, C3H8, at 44.097 g/mol. If your jar is the other form the molar mass differs and so will every mass you weigh, so check the label before using the figure. Salts that are sold as hydrates weigh more per mole because the water is part of the crystal.
Moles to grams reference for propane
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Carbon (C) | 3 | 12.011 | 36.033 | 81.71% |
| Hydrogen (H) | 8 | 1.008 | 8.064 | 18.29% |
| Total — one mole of propane | 44.097 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 44.097 g/mol.
| Wanted | Weigh (g) | Weigh (mg) | With 2% over (g) |
|---|---|---|---|
| 1 µmol | 0.000044 | 0.044097 | 0.000045 |
| 10 µmol | 0.00044097 | 0.44097 | 0.000449789 |
| 100 µmol | 0.0044097 | 4.4097 | 0.00449789 |
| 1 mmol | 0.044097 | 44.097 | 0.0449789 |
| 10 mmol | 0.44097 | 440.97 | 0.449789 |
| 50 mmol | 2.20485 | 2204.85 | 2.24895 |
| 100 mmol | 4.4097 | 4409.7 | 4.49789 |
| 250 mmol | 11.0243 | 11,024.2 | 11.2447 |
| 500 mmol | 22.0485 | 22,048.5 | 22.4895 |
| 750 mmol | 33.0727 | 33,072.8 | 33.7342 |
| 1 mol | 44.097 | 44,097 | 44.9789 |
| 2 mol | 88.194 | 88,194 | 89.9579 |
| 5 mol | 220.485 | 220,485 | 224.895 |
| 10 mol | 440.97 | 440,970 | 449.789 |
Weigh is the amount multiplied by 44.097 g/mol. The last column carries a 2% allowance, which is what you take when some of the solid will be left in the weighing boat.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Nitrogen | N2 | 28.014 | 35.696 |
| Oxygen | O2 | 31.998 | 31.252 |
| Hydrogen peroxide | H2O2 | 34.014 | 29.4 |
| Carbon dioxide | CO2 | 44.009 | 22.723 |
| Propane (this page) | C3H8 | 44.097 | 22.677 |
| Butane | C4H10 | 58.124 | 17.205 |
| Sulfur dioxide | SO2 | 64.058 | 15.611 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.