The molecular formula C8H18 can be categorized as which type of hydrocarbon?

The molecular formula C8H18 can be categorized as which type of hydrocarbon?

• A. Alkane
• B. Alkene
• C. Alkyne
• D. Aromatic

Answer: (A)

Recognize hydrocarbon families by saturation and bonding. Alkanes are saturated hydrocarbons with only single bonds and follow the formula CnH2n+2. For eight carbons, that gives H = 2(8) + 2 = 18, which matches C8H18 exactly. This means the molecule is an alkane (octane), with no rings or multiple bonds. Alkenes would have at least one C=C double bond and a hydrogen count of 2n, giving 16 hydrogens for eight carbons. Alkynes would have C≡C triple bonds with H = 2n − 2, giving 14 hydrogens for eight carbons. Aromatic hydrocarbons typically have ring structures and hydrogen counts that don’t fit 8 carbons with 18 hydrogens (for a monocyclic example, C8 would usually pair with far fewer than 18 hydrogens).

Recognize hydrocarbon families by saturation and bonding. Alkanes are saturated hydrocarbons with only single bonds and follow the formula CnH2n+2. For eight carbons, that gives H = 2(8) + 2 = 18, which matches C8H18 exactly. This means the molecule is an alkane (octane), with no rings or multiple bonds.

Alkenes would have at least one C=C double bond and a hydrogen count of 2n, giving 16 hydrogens for eight carbons. Alkynes would have C≡C triple bonds with H = 2n − 2, giving 14 hydrogens for eight carbons. Aromatic hydrocarbons typically have ring structures and hydrogen counts that don’t fit 8 carbons with 18 hydrogens (for a monocyclic example, C8 would usually pair with far fewer than 18 hydrogens).