Hydrocarbons

General formula of alkanes: CnH2n+2

General formula of alkenes: CnH2n

General formula of alkynes: CnH2n-2

General formula of alkyl groups: CnH2n+1

General combustion of alkanes: CnH2n+2 + (3n+1)/2 O2 -> nCO2 + (n+1)H2O

General combustion of any hydrocarbon: CxHy + (x + y/4)O2 -> xCO2 + (y/2)H2O

Combustion of methane: CH4(g) + 2O2(g) -> CO2(g) + 2H2O(l); ΔcH° = -890 kJ mol-1

Combustion of butane: C4H10(g) + 13/2 O2(g) -> 4CO2(g) + 5H2O(l); ΔcH° = -2875.84 kJ mol-1

C=C sigma bond enthalpy about 397 kJ mol-1; pi bond about 284 kJ mol-1

C=C double bond length = 134 pm; C-C single bond = 154 pm

C=C bond enthalpy = 681 kJ mol-1; C-C single bond in ethane = 348 kJ mol-1