Molar mass of histidine (C₆H₉N₃O₂)

The molar mass of histidine (C₆H₉N₃O₂) is 155.157 g/mol, summed from the IUPAC standard atomic weights of C x 6, H x 9, N x 3, O x 2.

Mass of sample

Amount of substance

mol

Molar mass

155.157g/mol

= Exact Molar mass of histidine

Moles in the sample mass: 0.064 450 847 mol
Mass of that amount of substance: 155.157
Molecules in the sample mass: 3.88132e+22

Show the working

Mass of sample = 10
Amount of substance = 1
Molar mass = 12.011*6 + 1.008*9 + 14.007*3 + 15.999*2 = 155.157
Moles in the sample mass = 10 / 155.157 = 0.064 450 8
Mass of that amount of substance = 1 * 155.157 = 155.157
Molecules in the sample mass = 0.064 450 8 * NA = 3.88132e+22

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 C₆H₉N₃O₂: 12.011 x 6 + 1.008 x 9 + 14.007 x 3 + 15.999 x 2 = 155.157 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.

Composition by mass

Element	Atoms	Atomic weight	Contribution (g/mol)	Share of mass
Carbon (C)	6	12.011	72.066	46.447 %
Nitrogen (N)	3	14.007	42.021	27.083 %
Oxygen (O)	2	15.999	31.998	20.623 %
Hydrogen (H)	9	1.008	9.072	5.847 %

Contributions add to the molar mass of 155.157 g/mol. Atomic weights are the IUPAC 2021 standard values.

Frequently asked

What is the molar mass of histidine?

155.157 g/mol, for the formula C₆H₉N₃O₂.

How do you convert grams of histidine to moles?

Divide the mass in grams by 155.157 g/mol. One gram of histidine is 0.00644508 mol.

How many grams are in one mole of histidine?

155.157 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.