The molecular mass of nitrogen is 28.02 atomic mass units (amu) or 28.02 grams per mole (g/mol).
Understanding Molecular Mass
The molecular mass represents the total mass of all atoms in a molecule. Nitrogen gas, found naturally, exists as a diatomic molecule (N₂), meaning two nitrogen atoms are bonded together.
Calculating Molecular Mass of Nitrogen (N₂)
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Find the atomic mass of nitrogen: The periodic table lists the atomic mass of nitrogen (N) as approximately 14.01 amu. Sources like the NIST Chemistry WebBook (https://webbook.nist.gov/cgi/cbook.cgi?ID=7727-37-9) provide more precise values (e.g., 14.0067 amu).
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Account for the diatomic nature: Since nitrogen gas is N₂, we multiply the atomic mass by 2: 14.01 amu/atom * 2 atoms = 28.02 amu.
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Units: The result, 28.02 amu, represents the molecular mass in atomic mass units. This is equivalent to 28.02 g/mol when considering molar mass (mass of one mole of molecules).
Different Sources, Similar Results
Several reputable sources confirm this calculation:
- Byjus.com: Calculates the molecular mass as 28.02 u (https://byjus.com/question-answer/what-is-the-molecular-mass-of-nitrogen/).
- Chemistry LibreTexts: States that the molecular mass of N₂ is (14.01 + 14.01) = 28.02 amu (https://chem.libretexts.org/Bookshelves/Introductory_Chemistry/Book%3A_Introductory_ChemistryOnline(Young)/04%3A_The_Mole_and_Measurement_in_Chemistry/4.2%3A_Molar_Mass).
- NIST Chemistry WebBook: Lists the molecular weight as 28.0134 (https://webbook.nist.gov/cgi/cbook.cgi?ID=7727-37-9).
- PubChem: Shows a molecular weight of 28.014 g/mol (https://pubchem.ncbi.nlm.nih.gov/compound/947).
Therefore, using the standard atomic mass of nitrogen, the molecular mass of nitrogen gas (N₂) is consistently determined to be approximately 28.02 amu or g/mol. Minor variations exist due to the use of slightly different atomic mass values from various sources.
