The molar mass of glycine, C2H5NO2, is 75.067 g/mol. That single number is what connects a mass you can weigh to an amount of substance you can react: one mole is 75.067 g, and a gram of it is 8.022e+21 formula units. The calculator turns any weighed mass into that count, and reports the amount in moles, millimoles and the mass of a single formula unit alongside it.
The figure comes from the formula. Glycine is 2 × 12.011 (C) + 5 × 1.008 (H) + 14.007 (N) + 2 × 15.999 (O), which is 75.067 g/mol, taking standard atomic weights, and every page here computes that sum rather than quoting it. Oxygen makes up the largest share of the mass: 2 of the 10 atoms in a formula unit are oxygen, and they account for 31.998 g of the 75.067 g, or 42.63% by mass. The derivation table below breaks the whole molecule down element by element.
The numbers a bench actually uses sit at the millimole scale. One millimole of glycine is 75.067 mg and one micromole is 75.067 µg, so a balance reading to a milligram places you within 13.32 µmol. A single formula unit weighs 1.2465e-22 g, which is why the count in the gauge runs into the sextillions for any mass you can see.
The smallest amino acid, a buffer component in electrophoresis and a sweetener. Highly soluble and stable in solution. At 75.067 g/mol it is heavier than 6 of the 21 organic compounds covered here, and that ranking matters more than it looks: ethylene glycol has a molar mass of 62.068 g/mol, so a gram of it contains 20.9% more formula units than a gram of glycine. Weigh by mass and you are not weighing equal amounts of substance.
Two practical things move the result. Purity below 100% means the weighed mass overstates how much compound you have — at 98% assay, 1.5013 g of every 75.067 g is not the compound — and any water picked up from the air does the same. Both are systematic, so they shift every solution made from that jar in the same direction.
The formula
m- The mass of glycine in grams
75.067- The molar mass of glycine in g/mol, derived from its formula
N- The number of formula units that mass contains
How it works, step by step
- Enter a mass of glycine in grams.
- It is divided by the molar mass, 75.067 g/mol, giving the amount in moles.
- That amount is multiplied by the Avogadro constant, 6.02214076 × 10²³ per mole, to give the number of formula units.
- The panel also reports the amount in moles and millimoles and the mass of one formula unit.
Worked examples
0.5 g of glycine as a molecule count
0.5 g divided by 75.067 g/mol is 0.00666072 mol, and multiplying by the Avogadro constant gives 4.011e+21 formula units of glycine. The same mass is 6.6607 mmol, which is the figure a reaction is actually planned in.
5 g of glycine as a molecule count
5 g divided by 75.067 g/mol is 0.0666072 mol, and multiplying by the Avogadro constant gives 4.011e+22 formula units of glycine. The same mass is 66.607 mmol, which is the figure a reaction is actually planned in.
50 g of glycine as a molecule count
50 g divided by 75.067 g/mol is 0.666072 mol, and multiplying by the Avogadro constant gives 4.011e+23 formula units of glycine. The same mass is 666.07 mmol, which is the figure a reaction is actually planned in.
How to read your score
Frequently asked questions
What is the molar mass of glycine (C2H5NO2)?
It is 75.067 g/mol. That is the sum of the standard atomic weights of every atom in the formula: 2 × 12.011 (C) + 5 × 1.008 (H) + 14.007 (N) + 2 × 15.999 (O). One mole of glycine therefore weighs 75.067 g, and a gram of it is 13.321 mmol.
What percentage of glycine is oxygen?
42.63% by mass. Each formula unit contains 2 oxygen atoms contributing 31.998 g of the 75.067 g total, so 100 g of glycine contains 42.63 g of oxygen and a kilogram contains 426.26 g of it.
How many molecules are in one gram of glycine?
About 8.022e+21. One gram is 0.0133214 mol, and each mole contains 6.02214076 × 10²³ formula units by definition of the mole, so the count is that constant divided by 75.067.
How much does a single molecule of glycine weigh?
1.2465e-22 g, which is 75.067 daltons. It is the molar mass divided by the Avogadro constant, and the number in daltons is numerically the same as the molar mass in g/mol — that equivalence is what makes the mole convenient.
Is molar mass the same as molecular weight?
They are the same number in ordinary use but not the same quantity. Molecular weight, properly relative molecular mass, is a ratio and has no unit: for glycine it is 75.067. Molar mass carries grams per mole: 75.067 g/mol. Because the mole is defined so those agree, you can read one off the other.
Why is the molar mass not a whole number?
Because standard atomic weights are averages over the isotopes found in nature. Oxygen is quoted as 15.999 rather than a whole number for that reason, and the same applies to the other elements here, which is why glycine comes out at 75.067 g/mol rather than 75.
Molar mass, composition and mole equivalents of glycine
| Element | Atoms | Atomic weight | Contribution (g/mol) | By mass |
|---|---|---|---|---|
| Oxygen (O) | 2 | 15.999 | 31.998 | 42.63% |
| Carbon (C) | 2 | 12.011 | 24.022 | 32% |
| Nitrogen (N) | 1 | 14.007 | 14.007 | 18.66% |
| Hydrogen (H) | 5 | 1.008 | 5.04 | 6.714% |
| Total — one mole of glycine | 75.067 | 100% |
Standard atomic weights, IUPAC 2021. The contribution column is atoms × atomic weight, and the total is the molar mass this page uses: 75.067 g/mol.
| Amount | Mass (g) | Mass (mg) | Formula units |
|---|---|---|---|
| 1 µmol | 0.000075 | 0.075067 | 6.022e+17 |
| 10 µmol | 0.00075067 | 0.75067 | 6.022e+18 |
| 100 µmol | 0.0075067 | 7.5067 | 6.022e+19 |
| 1 mmol | 0.075067 | 75.067 | 6.022e+20 |
| 10 mmol | 0.75067 | 750.67 | 6.022e+21 |
| 50 mmol | 3.75335 | 3753.35 | 3.011e+22 |
| 100 mmol | 7.5067 | 7506.7 | 6.022e+22 |
| 250 mmol | 18.7667 | 18,766.8 | 1.506e+23 |
| 500 mmol | 37.5335 | 37,533.5 | 3.011e+23 |
| 750 mmol | 56.3002 | 56,300.2 | 4.517e+23 |
| 1 mol | 75.067 | 75,067 | 6.022e+23 |
| 2 mol | 150.134 | 150,134 | 1.204e+24 |
| 5 mol | 375.335 | 375,335 | 3.011e+24 |
| 10 mol | 750.67 | 750,670 | 6.022e+24 |
Mass is the amount multiplied by 75.067 g/mol. The last column is that amount multiplied by the Avogadro constant, 6.02214076 × 10²³ per mole.
| Compound | Formula | Molar mass (g/mol) | Millimoles in 1 g |
|---|---|---|---|
| Urea | CH4N2O | 60.056 | 16.651 |
| Isopropyl alcohol | C3H8O | 60.096 | 16.64 |
| Ethylene glycol | C2H6O2 | 62.068 | 16.111 |
| Glycine (this page) | C2H5NO2 | 75.067 | 13.321 |
| Benzene | C6H6 | 78.114 | 12.802 |
| Glycerol | C3H8O3 | 92.094 | 10.858 |
| Toluene | C7H8 | 92.141 | 10.853 |
Ordered by molar mass. The last column is 1000/M, which is the number a weighed gram actually gives you.