From Atoms to Materials

80 ºC Fig. 13.32 During fractional distillation, hydrocarbons of different molecular sizes may be collected at different temperature ranges. Crude oil can be separated into fractions of different boiling point ranges by fractional distillation. During fractional distillation, different hydrocarbons in crude oil are heated to boil. They vaporize and rise. Then they condense at different temperature ranges, as separate fractions: • Fractions collected at lower temperature ranges contain hydrocarbons of smaller molecular sizes. (These hydrocarbons have lower boiling points.) • Fractions collected at higher temperature ranges contain hydrocarbons of larger molecular sizes. (These hydrocarbons have higher boiling points.) 160 ºC 120 ºC Molecular size: < < < 86 © United Prime Educational Publishing (HK) Limited 2024 All rights reserved; no part of this publication may be reproduced, photocopied, recorded or otherwise, without the prior written permission of the Publisher. Sample