O-LevelChemistryOrganic Chemistry5070/21 · Oct/Nov 2017 · Q55 Marks
A5 Hydrocarbons undergo complete combustion to form carbon dioxide and water.
- (a)Construct the equation for the complete combustion of butane, C4H10-[2]
- (b)The combustion of butane is exothermic. Explain in terms of bond making and bond breaking why this reaction is exothermic.[2]
- (c)Petroleum (crude oil) fractions contain hydrocarbons. Give one use of the paraffin (kerosene) fraction.[1]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.
- [1] A5(a) correct reactants and products
- [1] A5(a) balancing dependent on correct formulae
- [1] A5(b) bond breaking is endothermic and bond making is exothermic
- [1] A5(b) more energy released (in bond making) than absorbed (in bond breaking)
- [1] A5(c) jet fuel, heating oil
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