Alkenes Flashcards
Alkenes are…
Unsaturated hydrocarbons
What does a double covalent bond have that is important
High electron density, restricts rotation
What is the test for unsaturation
Add drops of bromine water, which should turn from orange to colourless if the substance is unsaturated
Reactivity of addition polymers
Unreactive
Uses of poly(chloroethene)
Pipes, bottles, insulation on cables
Why are addition polymers unreactive
Their backbone consists of strong, non-polar C-C bonds and are saturated. This means that they are not biodegradable
Explain the nature of intermolecular forces between polyalkane molecules
Since the hydrocarbon chains are often very long, the Van der Waal’s forces between the chains are often very strong and the polymers have relatively high melting and boiling points
What is a plasticiser for
Plasticisers are used to make a material like PVC softer and more flexible. They decrease the attraction between polymer chains by staying between the chains and allowing them to slide across each other
Conditions for addition polymerisation
High pressure, high temperature, O2 as the catalyst
What is the repeating unit of addition polymers
A part of a polymer whose repetition would produce the complete polymer chain
What is the difference between a monomer and a repeating unit
Monomer is the molecule before polymerisation, repeating unit is the molecule after polymerisation
What is stereoisomerism
Same molecular and structural formula, but different spatial arrangement of atoms
What is the monomer in PVC
Chloroethene
Uses of PVC before and after plasticising
Drainpipes before and plastic aprons after
What is a monomer
Small molecules, which bond together to form a polymer
How to produce alcohols from alkenes
React water with an alkene at 300 degrees, 70atms with conc. H3PO4
How to know the major product in the electrophilic addition of unsymmetrical alkenes
The more electronegative atom bonds with the carbon, which is bonded with the most carbons. This is a more stable carbocation. Tertiary > Secondary > Primary
What is an electrophile
An electron pair acceptor
Give an example of a plasticiser
Ester
What is the functional group isomer of an alkene
Cycloalkane
What cracking produces alkenes
Thermal cracking. High temperature and high pressure.
Why does bromine, a non-polar molecule, react with an alkene
The carbon- carbon double bond has a high electron density, which causes an induced dipole in bromine
