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Edexcel IAL Chemistry 4.17 Alkane combustion and halogenation

Identify complete or incomplete combustion from oxygen supply, conserve carbon and hydrogen in the equation and use light conditions to predict halogen reaction evidence.

Syllabus
First assessment 2019
Course
Chemistry YCH11
Level
AS

Exam points

  • Write balanced complete or incomplete combustion equations for named alkanes.
  • Define complete combustion through sufficient oxygen and fully oxidised products.
  • Predict alkane–halogen observations from light conditions and substitution products.

4.17—The reactions of alkanes with: i oxygen in the air (combustion) ii halogens question 1

[Maximum number: 2]

Fuels

Fuels burn in oxygen to release a lot of energy.
Many hydrocarbons and alcohols are used as fuels. During complete combustion, they produce carbon dioxide and water.

Petrol contains 2,2,4-trimethylpentane, an isomer of octane, that promotes smooth combustion.

Figure for Question 4.17—The reactions of alkanes with: i oxygen in the air (combustion) ii halogens question 1 — Edexcel A-Level Chemistry AS

2,2,4-trimethylpentane

Alcohols, such as methanol and ethanol, can be used as fuels either on their own or as additives in petrol.

The standard enthalpy change of combustion, ΔcH⊖\Delta_{\mathrm{c}} H^{\ominus}, of 2,2,4-trimethylpentane is −5461 kJ mol−1-5461 \mathrm{~kJ} \mathrm{~mol}^{-1}.

Write the equation for the complete combustion of 2,2,4-trimethylpentane, using molecular formulae. State symbols are not required.

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