What is the molar mass of helium gas he2?
The Correct Answer and Explanation is :
The molar mass of helium gas (He) is approximately 4.00 g/mol. It’s important to note that helium exists as a monatomic gas in its natural state, meaning that it is composed of single helium atoms rather than diatomic molecules (like O₂ or N₂). Therefore, the correct chemical formula for helium gas is simply He, not He₂.
Explanation of Molar Mass
Molar Mass Definition: The molar mass is the mass of one mole of a substance, expressed in grams per mole (g/mol). It is numerically equivalent to the atomic or molecular weight of the substance but is reported in grams. Molar mass is essential for converting between the mass of a substance and the number of moles, which is crucial in stoichiometric calculations in chemistry.
Calculation for Helium: The molar mass of helium is derived from the atomic mass of a single helium atom. The atomic mass of helium, as found on the periodic table, is about 4.00 atomic mass units (amu). Since one mole of any element contains Avogadro’s number of atoms (approximately (6.022 \times 10^{23})), the molar mass reflects the mass of these atoms collectively. For helium, this translates to about 4.00 g/mol, indicating that one mole of helium gas weighs about 4 grams.
Properties of Helium: Helium is the second lightest element after hydrogen and is classified as a noble gas. It is colorless, odorless, and tasteless, with very low reactivity due to its complete electron shell, making it stable and non-combustible. Helium’s low molar mass contributes to its high diffusion rate, which is why it is often used in balloons and airships. Additionally, its unique properties, such as low boiling and melting points, make it suitable for applications in cryogenics and as a cooling medium in various technologies.
In summary, helium’s molar mass is 4.00 g/mol, and understanding this concept is essential for various applications in chemistry and physics.