Alkenes And Polymers Flashcards
What 2 types of bonds make the C=C double bond?
Sigma and pi bonds
How are pi bonds formed?
2 p-orbitals overlap, forming second bond. It fixes the C atoms into place, at either end of double bonds -> this prevents any rotation on bond
Describe the structure of an alkene
Trigonal planar arrangement
Bond angle of 120*
3 electron density areas surround each carbon
Electron pairs repel as far out to minimise repulsions
Which are more reactive, alkanes or alkenes?
Alkenes
What reaction mechanism does an alkene undergo?
Electrophyllic addition
What is an electrophile?
Electrophile is an electron pair acceptor
What type of bond fission is required for an electrophyllic addition?
Heterolytic fission
What is heterolytic fission?
Heterolytic fission is the breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ve) and an anion (-ve)
Give an example of an industrial use of alkenes and explain how it is manufactured
Margarine
The manufacture of margarine:
Made from veg oil (liquids containing long hydrocarbon chains, C=C double bonds and polyunsaturated)
The oil must be hardened so it doesn’t soak.
Hydrogenation -> adds H molecules across double bonds in an addition reaction.
-> alters individual molecules
-> partially solidifies and hardens
What is a polymer?
A polymer is a long molecular chain built up from monomer units
What is a monomer?
A monomer is small molecules combine with many other monomers to form a polymer
What are addition polymers?
Addition polymer is a very long molecular chain, formed by repeated addition reactions of monomers
What is a repeat unit?
Specific arrangements of atoms that occurs in structure over and over again
What are the 2 industrial processes to produce polymers?
Radical polymerisation
The Ziegler-natha process
Give examples for the different uses of polymers
Polystyrene -> foam, packaging
Polypropylene -> containers, lab equipment (highly resistant to chemical attacks)
Polyethene -> grocery bags, bottles
