What is the general formula for alkanes, and are they saturated?

What is the general formula for alkanes, and are they saturated?

• A. CnH2n+2; unsaturated
• B. CnH2n; unsaturated
• C. CnH2n+2; saturated
• D. CnH2n+1; saturated

Answer: (C)

Alkanes are saturated hydrocarbons, meaning all carbon–carbon bonds are single bonds and each carbon has as many hydrogens as possible. With n carbon atoms, there are n−1 C–C bonds and the remaining bonds are C–H, which adds up to 2n + 2 hydrogens. So the general formula for open-chain alkanes is CnH2n+2. This maximum hydrogen content is what makes them saturated. For example, CH4, C2H6, and C3H8 fit the pattern as n = 1, 2, and 3, respectively. If you see CnH2n, that indicates an unsaturated hydrocarbon (such as an alkene) or a cycloalkane, not a standard alkane. A formula like CnH2n+1 would not represent a complete, stable alkane.

Alkanes are saturated hydrocarbons, meaning all carbon–carbon bonds are single bonds and each carbon has as many hydrogens as possible. With n carbon atoms, there are n−1 C–C bonds and the remaining bonds are C–H, which adds up to 2n + 2 hydrogens. So the general formula for open-chain alkanes is CnH2n+2. This maximum hydrogen content is what makes them saturated. For example, CH4, C2H6, and C3H8 fit the pattern as n = 1, 2, and 3, respectively. If you see CnH2n, that indicates an unsaturated hydrocarbon (such as an alkene) or a cycloalkane, not a standard alkane. A formula like CnH2n+1 would not represent a complete, stable alkane.