Molar mass of hydrogen (H₂)

The molar mass of hydrogen (H₂) is 2.016 g/mol, summed from the IUPAC standard atomic weights of H x 2. Molecular hydrogen, not the atomic weight of the element.

Mass of sample

Amount of substance

mol

Molar mass

2.016g/mol

= Exact Molar mass of hydrogen

Moles in the sample mass: 4.960 317 5 mol
Mass of that amount of substance: 2.016
Molecules in the sample mass: 2.98717e+24

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 1.008*2 = 2.016
Moles in the sample mass = 10 / 2.016 = 4.960 32
Mass of that amount of substance = 1 * 2.016 = 2.016
Molecules in the sample mass = 4.960 32 * NA = 2.98717e+24

Values are shown to six significant figures here; the arithmetic itself runs on exact fractions and is only rounded where a number is printed.

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The formula

Molar mass = sum over elements of (atomic weight x number of atoms)
For H₂: 1.008 x 2 = 2.016 g/mol
Moles = mass / molar mass; mass = moles x molar mass
Molecules = moles x 6.02214076 x 10^23 (the Avogadro constant, exact by definition)

Molar mass in grams per mole is numerically equal to the molecular mass in daltons, so this figure doubles as the molecular weight.

Atomic weights are the IUPAC 2021 standard values. Several elements have a range rather than a single value because isotope ratios vary between sources; the conventional single value is used here.

Molecular hydrogen, not the atomic weight of the element.

Composition by mass

Element	Atoms	Atomic weight	Contribution (g/mol)	Share of mass
Hydrogen (H)	2	1.008	2.016	100 %

Contributions add to the molar mass of 2.016 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of hydrogen?

2.016 g/mol, for the formula H₂.

How do you convert grams of hydrogen to moles?

Divide the mass in grams by 2.016 g/mol. One gram of hydrogen is 0.496032 mol.

How many grams are in one mole of hydrogen?

2.016 g, by definition of the molar mass.

Is molar mass the same as molecular weight?

Numerically yes, for the purposes of this calculation. Molecular weight is a dimensionless ratio and molar mass carries units of g/mol, but the digits are identical.

Where the numbers come from

IUPAC 2021 standard atomic weights; Avogadro constant fixed by the 2019 SI.