14.5 Alkene

Question 1

Describe Alkene

Answer 1

CnH2n
functional group - C=C bond
It is unsaturated -

Question 2

Describe cracking

Answer 2

breaking down larger hydrocarbons into smaller, more useful hydrocarbons - thermal decomposition of alkane
Longer chained alkanes are cracked to form a mixture of shorter chain alkane and alkene and somtimes Hydrogen
need heat and catalyst

Question 3

What is additional polymerisation

Answer 3

many monomers bond together via rearrangement of bonds without the loss of any atom or molecule

Question 4

How are polyethene form

Answer 4

formed from alkene monomers
double bond breaks and the monomers link in a long chain to form an addition polymer
Need high pressure, high temp. and catalyst

Question 5

What is addition reaction

Answer 5

2 reactants add together to from only 1 products

Question 6

Reaction between alkene and bromine water

Answer 6

C2H4 + Br2 -> C2H4Br2 -

Question 7

Hydrogen reaction with alkene

Answer 7

Form alkane, need catalyst (nickel)
C2H4 + H2 -> C2H6
Double bond breaks down to form alkane

Question 8

Steam reaction with alkene

Answer 8

Form alcohol with heat, pressure and catalyst
Need high temp. 300c and high pressure
c2h4 + h2o -> c2h5oh

Question 9

Complete combustion of alkene

Answer 9

Form co2 and h2o