How many hydrogen molecules are needed to form a saturated hydrocarbon?
The correct answer and explanation is:
To form a saturated hydrocarbon, the number of hydrogen molecules needed depends on the number of carbon atoms in the molecule. A saturated hydrocarbon, also known as an alkane, follows the general formula CnH2n+2C_nH_{2n+2}, where nn is the number of carbon atoms. This formula applies to alkanes because they have single bonds between carbon atoms and each carbon atom is bonded to enough hydrogen atoms to satisfy the carbon’s four bonds.
The simplest example is methane (CH4CH_4), where one carbon atom is bonded to four hydrogen atoms. As the number of carbon atoms increases, the number of hydrogen atoms also increases to maintain the saturated nature of the compound, where every carbon-carbon bond is a single bond and no carbon-carbon double or triple bonds exist.
For example:
- Ethane (C2H6C_2H_6): Two carbon atoms require six hydrogen atoms.
- Propane (C3H8C_3H_8): Three carbon atoms require eight hydrogen atoms.
- Butane (C4H10C_4H_{10}): Four carbon atoms require ten hydrogen atoms.
The key point is that each additional carbon atom in a saturated hydrocarbon requires two additional hydrogen atoms to maintain the stability and single-bond structure of the molecule.
In general, the number of hydrogen molecules required to form a saturated hydrocarbon is determined by the equation CnH2n+2C_nH_{2n+2}, with each hydrogen atom represented as part of the molecule, not as a molecule of H2H_2.
Therefore, when you are considering how many hydrogen molecules are needed, each molecule of hydrogen H2H_2 contains two hydrogen atoms, so you can divide the total number of hydrogen atoms in the molecule by two to find the number of H2H_2 molecules required.