4:11 know that a fuel is a substance that, when burned, releases heat energy A fuel is a substance that, when burned, releases heat energy (exothermic reaction). Hydr0Gen2018-04-25T21:50:24+00:00Categories: (b) Crude oil, 4 Organic chemistry, Edexcel iGCSE Chemistry|Tags: 4:11, Chemistry, Double, GCSE, GCSE_Chemistry_SpecPoint, SpecPoint, Topic: Alkanes & Crude Oil, Topic: Alkenes & Polymers|