The standard enthalpy change of combustion, ΔcH⊖, for alkanes increases by about 650 kJ/mol per CH2 group.
ðə stˈændɚd ɛnθˈælpi tʃˈeɪndʒ ʌv kəmbˈʌstʃən, dˈɛltək ˈeɪtʃ, fɔːɹ ˈælkeɪnz ˈɪŋkɹiːsᵻz baɪ ɐbˌaʊt sˈɪkshˈʌndɹɪd fˈɪfti kˈeɪ dʒˈeɪ slˈæʃ mˈɑːl pɜː sˌiːˈeɪtʃ tˈuː ɡɹˈuːp.