Alkanes and Alkenes

Question 1

Are alkanes and polar or non-polar, and why

Answer 1

Nonpolar because carbon and hydrogen have similar electronegativities

Question 2

What is the shape and bond angle of an alkane

Answer 2

Tetrahedral
109.5

Question 3

Describe the sigma bond in an alkane

Answer 3

The sigma bond is a covalent bond which has a direct overlap of electrons

Question 4

What type of intermolecular forces do alkanes have and why

Answer 4

London dispersion forces

Because bonds are non-polar

Question 5

What happens to the boiling point as alkane chain length increases and why

Answer 5

The boiling point increases because there is a larger surface area, so more London dispersion forces, so more energy is required to overcome the attraction

Question 6

How does branching affect boiling point of alkanes

Answer 6

Increased branching decreases boiling point, because there are fewer points of surface contact

So less London dispersion forces

So less energy needed to overcome the attractions

Question 7

Are alkanes soluble or insoluble

Answer 7

Insoluble

Question 8

What reactions do alkanes undergo

Answer 8

Combustion and free radical substitution

Question 9

what are the 3 stages of free radical substitution

Answer 9

Initiation
Propagation
Termination

Question 10

What bonds make up the C=c bond in alkenes

Answer 10

Pi and sigma bond

Question 11

How is a pi bond formed

Answer 11

Electrons in the adjacent p-orbitals overlap above and below the carbon atoms

Question 12

Which bond restricts rotation of carbon atoms

Answer 12

Pi bond

Question 13

What is the bond angle and shape of a double bond

Answer 13

Trigonal Planar
120

Question 14

Are alkenes more or less reactive than alkanes and why

Answer 14

More reactive due to high electron density of double bond and the fact the Pi bond is easier to break

Question 15

What intermolecular forces do alkenes have

Answer 15

London dispersion forces

Question 16

What is an electrophile

Answer 16

species that are electron pair acceptors

Question 17

what conditions are needed for electrophilic addition of H20 to an alkene

Answer 17

Steam
Acid catalyst

Question 18

What is the product of a hydration reaction

Answer 18

An alcohol

Question 19

What conditions are needed for the electrophilic addition of a hydrogen halide to alkenes

Answer 19

RTP

Question 20

What is the name given when a halogen reacts with an alkene

Answer 20

halogenation

Question 21

How can a alkene be converted to an alkane

Answer 21

Hydrogenation

150 degrees c
nickel catalyst

Question 22

What ways can plastics be disposed of

Answer 22

Landfill
Combustion
Reuse
Recycle
Feedstock

Question 23

Disadvantages of recycling

Answer 23

Expensive
Labour intensive
Require high technology

Question 24

How are photodegradable polymers broken down

Answer 24

Broken down chemically using energy with wavelengths similar to light

Question 25

What happens in organic feedstock

Answer 25

Plastics are separated and broken down into small organic molecules
Molecules can be used in other industries