The molecular mass of hydrogen gas (H2) is approximately 2.02 grams per mole. Here's a detailed explanation of how to calculate it:
Understanding Molecular Mass
Molecular mass, also known as molecular weight, is the mass of a molecule. It is calculated as the sum of the atomic masses of all the atoms in the molecule. The unit for molecular mass is usually grams per mole (g/mol).
Atomic Mass of Hydrogen
- The atomic mass of a single hydrogen atom (H) is approximately 1.01 g/mol.
Calculating the Molecular Mass of Hydrogen Gas (H2)
Since hydrogen gas exists as a diatomic molecule (H2), it consists of two hydrogen atoms bonded together.
Steps to Calculate:
- Identify the number of atoms: In H2, there are two hydrogen atoms.
- Multiply by atomic mass: Multiply the number of atoms by the atomic mass of hydrogen.
- Calculate the molecular mass of H2: 2 atoms * 1.01 g/mol/atom = 2.02 g/mol.
| Element | Number of Atoms | Atomic Mass (g/mol) | Subtotal (g/mol) |
|---|---|---|---|
| Hydrogen (H) | 2 | 1.01 | 2.02 |
| Total (H2) | 2.02 |
Practical Insights
- Diatomic Molecules: Hydrogen naturally occurs as a diatomic molecule (H2) in its gaseous state, meaning two hydrogen atoms are bonded together.
- Units: Always include the units (grams per mole) when expressing molecular mass.
Summary
The molecular mass of hydrogen gas (H2) is calculated by adding the atomic masses of two hydrogen atoms. The atomic mass of one hydrogen atom is approximately 1.01 g/mol. Therefore, the molecular mass of H2 is 2.02 g/mol. This means that one mole of hydrogen gas has a mass of 2.02 grams.
