æz ðə bˈɔɪlɪŋ pˈɔɪnt ʌv ˈælkeɪnz ɪz pɹaɪmˈɛɹᵻli dɪtˈɜːmɪnd baɪ wˈeɪt, ɪt ʃˌʊd nˌɑːt biː ɐ sɚpɹˈaɪz ðætðə bˈɔɪlɪŋ pˈɔɪnt hɐz ɐn ˈɔːlmoʊst lˈɪnɪɹ ɹᵻlˈeɪʃənʃˌɪp wɪððə sˈaɪz məlˈɛkjʊlɚ wˈeɪt ʌvðə mˈɑːlɪkjˌuːl.
As the boiling point of alkanes is primarily determined by weight, it should not be a surprise that the boiling point has an almost linear relationship with the size (molecular weight) of the molecule.