Alkenes: structure and electrophilic additionEdexcel A-Level Chemistry: Mind map

Exam questions on Alkenes: structure and electrophilic addition

1. Margarine is made from vegetable oils. The oil molecules contain several C=C double bonds, which is why the oils are liquid at room temperature. The oil is hydrogenated by reacting it with hydrogen gas in the presence of a catalyst, so that it becomes a spreadable solid.
   One type of oil molecule has four C=C double bonds. Calculate the volume of hydrogen, at room temperature and pressure, needed to hydrogenate 0.0250 mol of this oil until it has no C=C bonds left. (1 mol of gas occupies 24.0 dm³ at room temperature and pressure.)2 marks
2. Propene, CH₃CH=CH₂, reacts with hydrogen bromide at room temperature by electrophilic addition. The product is mainly 2-bromopropane.
   Explain why 2-bromopropane is the major product of this reaction.2 marks
3. A technician has two colourless liquids, cyclohexane and cyclohexene, which both contain six carbon atoms. She tests both with bromine water and then plans to react the cyclohexene with liquid bromine.
   Describe a chemical test that distinguishes cyclohexene from cyclohexane, including the observation with each liquid.3 marks