Reaction mechanismsAQA A-Level Chemistry: Mind map

Exam questions on Reaction mechanisms

1. Methane reacts with chlorine in the presence of ultraviolet light to form chloromethane and hydrogen chloride. The reaction does not occur in the dark. It is a free-radical reaction.
   Write equations for the two propagation steps of this reaction.2 marks
2. An organic chemist is drawing the mechanism for the reaction of bromoethane with hydroxide ions: CH₃CH₂Br + OH⁻ → CH₃CH₂OH + Br⁻. The C–Br bond is polar, with the carbon atom δ+.
   Describe the two curly arrows needed to show this mechanism.2 marks
3. In the stratosphere, ultraviolet radiation breaks a C–Cl bond in the CFC dichlorodifluoromethane, CCl₂F₂, to form chlorine atoms. These chlorine atoms then take part in reactions that destroy ozone, O₃.
   Write an equation for this bond-breaking step, name the type of bond fission involved and state what happens to the pair of electrons in the C–Cl bond.3 marks