Final answer:
The molar mass of hydrogen gas (H₂) is ≈2.0158 g/mol. This value is crucial for conversions in chemical equations and is used along with Avogadro's number in stoichiometry.
Step-by-step explanation:
The molar mass of hydrogen gas (H₂) can be calculated by adding the atomic masses of the two hydrogen atoms in the molecule. Each hydrogen atom has an atomic mass of approximately 1.0079 amu (atomic mass units). Therefore, the molar mass of molecular hydrogen (H₂) is about 2.0158 grams per mole (g/mol). This value is essential in stoichiometry for converting between grams and moles, and it also appears in various equations, such as the ideal gas law where the number of moles (n) is used.
For instance, to determine the number of molecules in 6.022 grams of H₂, dimensional analysis can be used with Avogadro's number (6.02 × 10²³ molecules/mol), which represents the number of units in one mole of a substance. The calculation forms a basis for quantifying substances in chemical reactions, highlighted in stoichiometry scenarios such as those involving the formation of water from hydrogen and oxygen.