What is the molar mass of methane (
)? 18 g/mol 20. g/mol 12 g/mol
The Correct Answer and Explanation is:
The correct answer is 16.04 g/mol .
The molar mass of a chemical compound represents the total mass of all the atoms in one mole of that substance. It is expressed in units of grams per mole ( g/mol ). To find the molar mass of methane (CH₄), one must sum the atomic masses of its constituent atoms based on its chemical formula.
The calculation proceeds in a straightforward manner. First, identify the elements present in the molecule and the number of atoms of each element. The formula CH₄ indicates that a single molecule of methane contains one carbon (C) atom and four hydrogen (H) atoms.
Next, find the standard atomic mass of each element from the periodic table. The atomic mass of carbon is approximately 12.011 g/mol , and the atomic mass of hydrogen is approximately 1.008 g/mol .
Then, calculate the total mass contribution from each element in the compound.
- For carbon, its contribution is the mass of one atom: 1 atom × 12.011 g/mol = 12.011 g/mol .
- For hydrogen, its contribution is the mass of four atoms: 4 atoms × 1.008 g/mol = 4.032 g/mol .
Finally, add the mass contributions from all the elements together to get the molar mass of the methane molecule.
Molar Mass of CH₄ = (Mass of Carbon) + (Mass of Hydrogen)
Molar Mass of CH₄ = 12.011 g/mol + 4.032 g/mol = 16.043 g/mol .
For most general chemistry purposes, this value is rounded to two decimal places, resulting in 16.04 g/mol . This number is fundamental in stoichiometry, as it provides a direct conversion factor between the mass of a methane sample and the number of moles it contains, which is crucial for predicting reactant and product quantities in chemical reactions.thumb_upthumb_down
