Calculate the percentage by mass of the indicated element in the following compounds: (a) hydrogen in methane, CH4, the major hydrocarbon in natural gas

Verified step by step guidance

1. Determine the molar mass of methane (CH4). Methane consists of one carbon atom and four hydrogen atoms. Use the atomic masses from the periodic table: Carbon (C) approximately 12.01 g/mol and Hydrogen (H) approximately 1.008 g/mol.
2. Calculate the total molar mass of methane by adding the molar mass of carbon and the molar masses of the four hydrogen atoms.
3. Calculate the total mass of hydrogen in one mole of methane by multiplying the molar mass of hydrogen by the number of hydrogen atoms in the methane molecule.
4. To find the percentage by mass of hydrogen in methane, divide the total mass of hydrogen in the molecule by the total molar mass of methane.
5. Multiply the result from the previous step by 100 to convert it to a percentage. This will give you the percentage by mass of hydrogen in methane.

Key Concepts

Molar Mass

Molar mass is the mass of one mole of a substance, typically expressed in grams per mole (g/mol). It is calculated by summing the atomic masses of all the atoms in a molecule. For methane (CH4), the molar mass is derived from the atomic mass of carbon (C) and hydrogen (H), which are approximately 12.01 g/mol and 1.01 g/mol, respectively.

Percentage by Mass

Percentage by mass is a way to express the concentration of an element in a compound. It is calculated by dividing the mass of the element in one mole of the compound by the total molar mass of the compound, then multiplying by 100. This calculation helps in understanding the composition of compounds and is essential for stoichiometric calculations.

Hydrocarbons

Hydrocarbons are organic compounds composed solely of hydrogen and carbon atoms. They can be classified into aliphatic (alkanes, alkenes, alkynes) and aromatic hydrocarbons. Methane (CH4) is the simplest alkane and serves as a primary example of hydrocarbons, which are significant in energy production and various chemical processes.