Alkenes: structure and electrophilic additionEdexcel A-Level Chemistry: Flashcards

What these 15 flashcards ask

What is the general formula of alkenes?
What does unsaturated mean?
What bonds make up a C=C double bond?
What is an electrophile?
What is heterolytic fission?
What conditions and product form when an alkene reacts with hydrogen?
What does steam with an acid catalyst convert an alkene into?
What is the product of an alkene reacting with acidified potassium manganate(VII)?
What is the product when ethene reacts with bromine?
What is the test for a C=C double bond?
Why can bromine act as an electrophile in addition to alkenes?
What is a carbocation?
Put carbocations in order of stability.
Why is the tertiary carbocation the most stable?
Which is the major product of propene with HBr?

Exam questions on Alkenes: structure and electrophilic addition

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
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
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

Written by the Exaim team, led by Shaun Daswani (Head of Upper Secondary, Improve ME Institute; MSc Financial Mathematics, Imperial College London; BSc, UCL) and Jason Daswani (operational lead, Improve ME Institute; LSE).