AQA A LEVEL CHEMISTRY: YEAR 1- ALKENES QUESTIONS AND ANSWERS WITH SOLUTIONS 2024

AQA A LEVEL CHEMISTRY: YEAR 1 - ALKENES QUESTIONS AND ANSWERS WITH SOLUTIONS 2024 What is an alkene? - ANSWER An unsaturated hydrocarbon What is an unsaturated hydrocarbon? - ANSWER A compound containing only carbon and hydrogen atoms and containing at least one carbon carbon double bond What are van der Waals forces? - ANSWER Relatively weak intermolecular forces caused by temporary dipole dipole interaction What is the general formula for an alkene? - ANSWER CnH2n How would you name an alkene given its displayed formula? - ANSWER Identify the longest carbon chain Identify the position of the carbon carbon double bond Identify any side chains What are structural isomers? - ANSWER Molecules with the same molecular formula, but with different a structural formula What are stereoisomers? - ANSWER Molecules with the same molecular AND structural formula but a different 3D arrangement of their atoms in space What is E -Z isomerism? - ANSWER The highest priority groups are on the same side of the double bond Describe the C=C double bond - ANSWER Double covalent bond Planar bond Area of high electron density How do you assign the highest priority of groups in E -Z isomerism? - ANSWER The highest atomic number closest to the double bond has the highest priority If two groups have e.g. Only carbon and hydrogen, then the one with the most carbon atoms is assigned the highest priority What are Z isomers? - ANSWER Molecules where the highest priority groups are on the same side What are E isomers? - ANSWER Molecules where the highest priority groups are on opposite sides What is addition polymerisation? - ANSWER The reaction by which alkenes (or substituted alkenes) react with other alkene (or substituted alkene) molecules to form polymers What polymer would the monomer ethene form? - ANSWER Poly(ethene) What is a polymer? - ANSWER A long chain of repeating monomer units joined together Why are addition polymers unreactive? - ANSWER They lack the reactive carbon -carbon double bond Which is an area of high electron density And so vulnerable to electrophilic attack What is PVC? - ANSWER Poly(chloroethene) What is PVC used for? - ANSWER PVC: Wellies, raincoats, uPVC: Drainpipes, window/door frames Electrical wire insulation Describe PVC - ANSWER A rigid plastic What is the difference between uPVC and PVC? - ANSWER A plasticiser molecule has been added to PVC to make it more flexible for its use in clothing