Alkanes as fuels and pollutionEdexcel A-Level Chemistry: Mind map

Exam questions on Alkanes as fuels and pollution

1. A refinery separates crude oil by fractional distillation. One fraction contains mainly heptane, C₇H₁₆, a straight-chain alkane. Part of this fraction is processed further so that it can be blended into petrol for use in car engines.
   Explain why the refinery reforms some of the straight-chain alkanes in this fraction before blending them into petrol.2 marks
2. A petrol car is driven on a motorway. Air enters the engine and the fuel burns at a very high temperature in a limited supply of oxygen, so the exhaust gases contain carbon monoxide, nitrogen monoxide, unburned hydrocarbons and carbon particulates before they pass through the exhaust system.
   Write an equation for the formation of nitrogen monoxide in the engine and explain why it forms in the engine but not in the cold air outside the car.2 marks
3. The exhaust system of the car contains a catalytic converter. This is a honeycomb of ceramic coated with a thin layer of platinum, palladium and rhodium. The exhaust gases pass through it before leaving the car.
   The converter helps to solve two pollution problems when carbon monoxide reacts with nitrogen monoxide. Write an equation for this reaction and explain how it reduces each problem.3 marks