alkenes

Question 1

What are alkenes?

Answer 1

Alkenes are unsaturated hydrocarbons.

Question 2

What is the general formula for alkenes?

Answer 2

The general formula for alkenes is CnH2n.

Question 3

What does it mean for alkenes to be unsaturated?

Answer 3

It means there is at least one double covalent bond.

Question 4

What types of elements do alkenes contain?

Answer 4

Alkenes contain hydrogen and carbon only.

Question 5

What is the significance of double bonds in alkenes?

Answer 5

Double bonds have a high electron density, making alkenes fairly reactive.

Question 6

How do cycloalkenes differ from their straight-chain counterparts?

Answer 6

Cycloalkenes have 2 fewer hydrogens than their straight-chain version.

Question 7

Why are alkenes attacked by electrophiles?

Answer 7

Alkenes are attacked by electrophiles due to their double bond having a high density of electrons.

Question 8

What role does an electrophile play in reactions with alkenes?

Answer 8

An electrophile is an electron pair acceptor that is attracted to the double bond.

Question 9

What is a test for alkenes involving bromine?

Answer 9

A test for alkenes is the decolouration of bromine water.

Question 10

What color change indicates the presence of an alkene when bromine water is added?

Answer 10

The color changes from brown-orange to colorless.

Question 11

What happens when bromine is added to an alkene?

Answer 11

Bromine, as the electrophile, adds to the alkene forming a dibromoalkane (colorless).

Question 12

What are allenes?

Answer 12

Allenes are monomers which join to form addition polymers.

Allenes can participate in polymerization reactions to create complex structures.

Question 13

What are the two types of polymers?

Answer 13

Polymers can be classified as:
* Natural
* Synthetic

Natural polymers include proteins and natural rubber, while synthetic polymers include poly(ethene) and poly(propene).

Question 14

What are examples of natural polymers?

Answer 14

Natural polymers include:
* Proteins
* Natural rubber

These polymers are derived from natural sources and play critical roles in biological systems.

Question 15

What are examples of synthetic polymers?

Answer 15

Synthetic polymers include:
* Poly(ethene)
* Poly(propene)

These polymers are manufactured through chemical processes and are widely used in various industries.

Question 16

What are alkenes?

Answer 16

Alkenes are monomers which join to form addition polymers.

Alkenes contain at least one carbon-carbon double bond, making them reactive in polymerization.

Question 17

What is Addition polymerisation?

Answer 17

A process where small molecules join together to make polymers

It involves the formation of long chain molecules from monomers.

Question 18

Define Monomer.

Answer 18

A small molecule that can join together to form a polymer

Monomers are the building blocks of polymers.

Question 19

What is a Polymer?

Answer 19

A long chain molecule made from many small molecules joined together

Polymers can have various properties depending on their monomers.

Question 20

What is Condensation polymer?

Answer 20

A polymer formed by the joining of small molecules with the release of another small molecule (e.g., water)

This process often involves the formation of covalent bonds.

Question 21

What characterizes an Addition polymer?

Answer 21

Formation of long chain molecules from small molecules joining together without any other products

This process typically does not release small molecules like water.

Question 22

Fill in the blank: A _______ is a small molecule that can join together to form a polymer.

Answer 22

Monomer

Question 23

Fill in the blank: A _______ is a long chain molecule made from many small molecules.

Answer 23

Polymer

Question 24

True or False: Addition polymerisation produces other small molecules as byproducts.

Answer 24

False

Question 25

What happens during the process of condensation in polymer formation?

Answer 25

Small molecules join together, releasing another small molecule, such as water ## Footnote This is a key difference from addition polymerisation.

Question 26

What is the main difference between Addition and Condensation polymerisation?

Answer 26

Addition polymerisation does not produce byproducts, while condensation does ## Footnote This distinction is crucial for understanding different polymerization methods.

Question 27

What is needed to make poly(propene)?

Answer 27

The monomer propene and a few of these bonded together to form poly(propene) ## Footnote Poly(propene) is a polymer derived from the monomer propene

Question 28

What happens to the double bond in propene when forming the polymer?

Answer 28

The double bond opens up to form the polymer ## Footnote This process is known as polymerization

Question 29

What type of forces are present between most polyalkene chains?

Answer 29

Van der Waals forces ## Footnote These forces are weak intermolecular interactions

Question 30

How do van der Waals forces relate to the length of polymer chains?

Answer 30

The longer the chain and the closer they are to each other, the more van der Waals forces you have ## Footnote This affects the physical properties of the polymer

Question 31

What characteristics do shorter polymer chains with a lot of branching tend to have?

Answer 31

More flexible and weaker ## Footnote Branching affects the packing and overall strength of the polymer

Question 32

What characteristics do polymers with little or no branching and long chains tend to have?

Answer 32

More rigid and stronger ## Footnote The structure allows for better alignment and packing

Question 33

What is an example of a polymer that can have halogens, such as chlorine?

Answer 33

PVC (polyvinyl chloride) ## Footnote PVC is widely used in construction and plumbing due to its properties

Question 34

What type of forces can polymers with halogens form?

Answer 34

Stronger permanent dipole-dipole forces ## Footnote These forces lead to different properties compared to non-polar polyalkenes

Question 35

True or False: Most polyalkenes are polar.

Answer 35

False ## Footnote Most polyalkenes are non-polar

Question 36

What are plasticisers?

Answer 36

Plasticisers are added to polymers to change their properties ## Footnote Plasticisers make polymers more flexible by sliding between the polymer chains, pushing them apart.

Question 37

How do plasticisers affect polymer chains?

Answer 37

Plasticisers weaken the intermolecular forces between the chains, allowing them to slide over each other more easily ## Footnote This makes the polymer easier to bend.

Question 38

Which polymer is commonly modified by plasticisers?

Answer 38

PVC - poly (vinyl chloride) ## Footnote PVC is made from long, closely packed polymer chains that are hard but brittle.

Question 39

What is the effect of adding plasticisers to PVC?

Answer 39

It makes PVC more flexible ## Footnote Flexible PVC is used for applications like electrical cable insulation and clothing.

Question 40

Fill in the blank: Plasticisers are commonly used to change the properties of _______.

Answer 40

PVC

Question 41

True or False: Plasticisers make polymers more rigid.

Answer 41

False

Question 42

What is the structural formula for chloroethene?

Answer 42

C=C ## Footnote Chloroethene is also known as vinyl chloride.

Question 43

What is one application of flexible PVC?

Answer 43

Electrical cable insulation ## Footnote Flexible PVC is preferred for applications requiring bendability.