Fractions of distillation..... Some of the fractions which result from fractional distillation seem to share carbons of the same length - yet these form different fractions. Why? Eg - Petrol is carbon chain length 4 - 12, naptha is 7 - 14 and kerosine is 11 -15; why the overlap when they boil at very distinct temps. ie - petrol 40 - 100, naptha is 100 - 150 and kerosine is 150 - 250 degrees C. Thanks.