1What are alkenes?
Unsaturated hydrocarbons
2What is the general formula of an alkene?
CnH2n
3What is the bond angle of a Carbon carbon double bond?
120
4What shape is a carbon carbon double bond?
planar
5What type of bonds do carbon carbon double covalent bonds consist of?
sigma and pi
6what do pi bonds have
high electron density
7What are electrophiles?
Electron pair acceptors
8What are steroisomers?
Substances with same structual formula but different spatial arrangement of atoms
9Why does E Z isomers exist?
Exist due to restricted bond rotation of carbon carbon double bond and each carbon has two different groups attacher to it
10What other condition must there be for EZ stereoisomers to exist?
Two different groups attached to both ends of the double bond
11What is an addition reaction?
A reaction where two molecules react together to produce one
12Whata re the conditions for bromine reacting with an alkene via electrophilic addition?
Room temperature
13How is bromine attracted to double bond if its non polar
As Bromine is near alkene the pi bond is very electron dense which cause it to repel the electron pair in bromine and induce a dipole
14If an alkene is unsymmetrical how many products can be formed from electrophilic addition?
Two
15What is the major product?
Product formed by the more stable carbocation intermediate
16what is the most stable carbocation?
tertiary
17What does hydration of alkenes form?
Alcohols
18What are essential conditions for hydration reactions?
High temperatures, high pressure? concentrated acid catalyst
19Advantages and disadvantages of hydration?
High pressure ate costly, no waste products so high atom economy,
20What is the test for alkenes?
Add bromine water, alkenes decolourise it
21Why are poly alkenes unreactive?
strong C C bonds and C-H bonds
22What polymers are formed from alkenes?
addition polymers
23State general features of poly(chloroethene)?
water proof, an electrical insulator, doesnt react with acids,
24why is poly chloroethene rigid?
Strong intermolecular forces between polymer chains which prevents them sliding over each other
25what does plasticiser do to polychloroethene?
weakens the intermolecular forces which allows the chains to move more easily resulting in more flexibility
26What does sulfuric acid plus alkenes make?
alkyl hydrogen sulfate
27What is a hydration reaction?
Reaction where water is added to a molecule
28Why is there an attraction betwrrn C=C and Bromine?
C=C is very electron rich which polarises Br2 . Slightly positive region is attracted to C=C bond
29What happens if water in and water out is the wrong way?
Less efficient cooling and the product may not condense
30How does greenhouse gas contribute to global warming?
Absorbs IR radiation and molecule has polar bonds which can vibrate
31Why is polypropebe unreactive?
Has no polar bonds
32Explain pi bond in relation to the carbon carbon double bond of an alkene (1)
Bond in a double bond formedby the overlap of p orbitals
33Why are alkenes generally more reactive than alkanes? (2)
Alkenes have a carbon carbon double broken
pi bond is weaker than sigma bond so broken more readily
34Give one advantage and one disadvantage of the disposal of polyalkenes? (2)
Avoids landfill
release carbon dioxide which contributes to global warming