Alkenes

Question 1

How is a sigma bond formed ?

Answer 1

Direct overlap of s orbitals
between bonded atoms

Question 2

How can waste polymers of alkenes be processed sustainably ?

Answer 2

Combustion (Providing energy as an alternative to fossil fuels)
Using as organic feedstock
Recycling the waste polymer

Question 3

What are the reagents and conditions for hydration of alkenes to take place ?

Answer 3

H20(g)
High pressure
High temperature ( Greater than or equal to 100 degrees)
H3PO4 catalyst

Question 4

What are the reagents and conditions for hydrogenation of alkenes to take place ?

Answer 4

Ni Catalyst
150 degrees celsius

Question 5

What is observed when an alkene reacts with bromine ?

Answer 5

Bromine water
Orange - colourless

Question 6

What features of compounds allow for E/Z isomerism ?

Answer 6

C=C bond - limiting rotation of molecule
2 different groups attached to each carbon in the C=C bond

Question 7

What is the definition of homolytic fission ?

Answer 7

Covalent bond breaking
One electron from the bond goes to each specie

Question 8

When does homolytic fission often occur ?

Answer 8

In free radical substitution of alkanes

Question 9

What is the definition of heterolytic fission ?

Answer 9

Covalent bond breaking
More electronegative specie takes both electrons/all electrons go to 1 specie

Question 10

How is HCl removed from the waste gases produced ?

Answer 10

Passing through an alkali/carbonate

Question 11

How would you test for the presence of an alkene ?

Answer 11

React with Br2
Turns bromine water (Orange) to colourless

Question 12

Define ‘ Stereoisomers ‘

Answer 12

Same structural formula
Different arrangement of atoms in space

Question 13

Describe a difference between a sigma bond a pi bond

Answer 13

Pi bond is above nuclei, Sigma is between bonded atoms
Sigma bond is the direct overlap of orbitals, Pi bond is the sideways overlap of orbitals
Pi bond has a lower bond enthalpy than the sigma bond