Polymers

Question 1

How are they made

Answer 1

Joining together thousands of identical molecules
= monomers

Question 2

How to form condensation polymers

Answer 2

React two different monomers
Each monomer has two main of the same functional groups
= lose small molecules like water

Question 3

Amino acid functional groups

Answer 3

• H2N
• COOH
• 2 different functional groups
  = means they can form condensation polymers

Question 4

How to form a protein

Answer 4

• combine different amino acids into the same chain
  = call the polymer a protein

Question 5

Two types of polymerisation

Answer 5

• condensation polymerisation
• addition polymerisation

Question 6

Compare condensation and addition polymerisation

Answer 6

Similarities
- Both processes produce large molecules / polymers
- All covalent bonds

Differences
In addition polymerisation:
- Usually identical monomers
- 100% atom economy

In condensation polymerisation:
- Requires monomers with different functional groups
- Can often be done at close to room temperature

Question 7

Properties of polymers are reliant on their

Answer 7

• Monomer units
• Size of chains
• Additional chemical attachment
• Molecular structure and density

Question 8

Describe thermosetting

Answer 8

• Harder plastics with denser structures.
• Do not melt easily
  = cross linking

Question 9

Describe thermosoftening

Answer 9

• Softer plastics with less dense structure
• Melt easily when heated

Question 10

Different types of polyethene

Answer 10

High density
Low density

Question 11

Describe HD polythene

Answer 11

• Use a catalyst at 50°C and slightly raised pressure
• Straighter chains packed closer together

Question 12

Describe LD polythene

Answer 12

• Uses very high pressures and a trace of oxygen
• Randomly branched, cannot pack closely together

Question 13

How to change polymers

Answer 13

We can soften polymers by adding plasticisers
= reduce the melting point and rigidity of the polymer chains
We can increase the hardness of soft polymers by adding cross-links between polymers chains
=These are covalently bonded therefore huge amounts of energy are needed to break them
Polymers, thermosetting,

Question 14

Types of glass

Answer 14

• Soda lime glass - windows etc (most of the glass we use)
• Borosilicate glass (pyrex) - cookware

Question 15

What is soda lime glass made of

Answer 15

• Sand (SiO2)
• Limestone (CaCO3)
• Soda (Na2CO3)
  These are heated to 1500oC.
  They melt and then react to form glass. The bonds are a mix of covalent and ionic.

Question 16

How is borosilicate glass made

Answer 16

• made of sand (SiO2) and boron trioxide (B2O3)
• It has a higher melting point than soda-lime glass and is used for ovenware and test tubes

Question 17

Ceramics properties

Answer 17

• The higher the firing temperature the harder the ceramic formed.
• The brittleness is due to the presence of crystaline regions.

Question 18

Describe reinforced concrete

Answer 18

• contains a steel mesh embedded in the concrete
• concrete provides compressive strength
• steel rods provide tensile strength

Question 19

Describe addition monomers

Answer 19

Repeating unit has same atoms as the monomer
= no other molecule formed in reaction

Question 20

Describe polypeptide

Answer 20

Polymer made of only one type of amino acid

Question 21

Describe structure of DNA

Answer 21

Consists of 2 polymer chains made from monomers called nucleotides
Double helix

Question 22

Examples of things made by naturally occurring polymers

Answer 22

Proteins
= polymers of amino acids
Starch
= polymer of glucose
Cellulose
= polymer of glucose

Question 23

What do thermosoftening polymers do when heated

Answer 23

Melt when heated
= we can reshape them while they’re soft
= then they go back to a solid when we cool them back down

Question 24

Reaction of thermosetting polymers when heated

Answer 24

Strong cross links aren’t broken by heat
= why they don’t melt when heated

Question 25

Describe addition polymers

Answer 25

Monomers are alkenes