Condensation Polymerisation

Question 1

What is condensation polymerisation

Answer 1

Condensation ploymerisation occurs when monomers combine to form a macromolecule (polymer) with the removal of small molecules such as water

Question 2

Formation of nylon

Answer 2

Nylon is a synthetic fibre made by condensation polymerization. It is a polyamide made from a dicarboxlyic acid and a diamine

Dicarboxlyic acid( an amine with two -COOH groups)
Diamine( an amine with two -NH2 groups)

Question 3

How do monomers react to form nylon?

Step 1:

Answer 3

Write out the structural formula of several monomer molecules. Arrange the two types of monomers in alternating manner

Question 4

Step 2(nylon):

Answer 4

Remove a water molecule from each pair of monomer molecules.

Question 5

Step 3(nylon)

Answer 5

Join the monomer molecules together to form the polymer

Question 6

Why is nylon a polyamide?

Answer 6

As it contains many amide linkages

Question 7

Uses of nylon:

Answer 7

• strong yet light; can be stretched without breaking

- To make strong ropes, fishing lines and zippers

Question 8

Formation of terylene

Answer 8

A synthetic fibre made from condensation polymerisation

It is a polyester formed from a dicarboxlyic acid and diol

Question 9

How do monomers react to form terylene

Step 1:

Answer 9

Write out the structural formulae of several monomer molecules. Arrange the 2 types of monomers in alternating manner

Question 10

Step 2:

Answer 10

Remove a water molecule from each pair of monomer molecules

Question 11

Step 3:

Answer 11

Join the monomer molecules together to form the polymer

Question 12

Why is terylene a polyester

Answer 12

As it contains many ester linkages

Question 13

Uses of terylene

Answer 13

Used in making clothes, sails and sleeping bags

Question 14

Differences between addition polymerisation and condensation polymerisation

Answer 14

Addition polymerisation- condensation polymerisation

1) Only 1 product formed- 1 product formed and small molecules eliminated as byproducts
2) monomers are unsaturated (Contain C=C bond)- 2 sets of monomers(eg diol and dicarboxylic acids) with different functional groups
3) Mass of polymer is equal to the sum of the mass of its monomers- mass of polymer is less than the sum of the mass of its monomers(small molecules eliminated)
4) High temperature and pressure-Room temperature and pressure)

Question 15

Thermal stability of metal

Answer 15

The more reactive the metal, the more stable a combined it forms. Therefore, it is more difficult/requires more energy to thermally decompose.

Question 16

Thermal decomposition of metal carbonates

Answer 16

Potassium sodium———-may not thermally decompose

Calcium magnesium zinc iron lead copper silver——- thermal decomposes to tourism oxides and carbon dioxide gas

Question 17

Thermal decomposition of metal hydroxides

Answer 17

Potassium sodium may not thermally decompose

Calcium magnesium zinc iron lead copper silver——— thermally decomposes to form oxides and H2O

Question 18

Thermal decomposition of metal nitrates

Answer 18

Potassium sodium——— thermally decompose to form nitrates and oxygen
gas
Calcium magnesium zinc iron lead copper silver———thermally decomposes to form oxides, nitrogen dioxide and oxygen gas

Question 19

Thermal decomposition of metal sulfates

Answer 19

Potassium sodium calcium magnesium zinc———may not thermally decompose
Iron lead copper silver———-thermally decomposes to form oxides and SO2/SO3

Question 20

Obtaining metals from ores

Answer 20

The more reactive the metal, the more stable a compound it forms. Therefore, it requires more energy to reduce the ore to become a metal.

Question 21

Methods of extraction - electrolysis

Answer 21

Electricity is passed through the ore to reduce it into element form. Performed at high temperatures in order to maintain the ore in a molten state
Less reactive metals like copper can be extracted form aqueous solutions instead to save cost.

Question 22

Method of extraction- carbon and reduction

Answer 22

Potassium sodium calcium magnesium——- more reactive metals form extremely stable ores, and hence may not be extracted through carbon reduction
Zinc iron lead copper silver——- metal ore is heated Coke. The more reactive the metal, the higher the temperature required for the reaction

Question 23

Gold is a precious metal which is below silver in the reactivity series. Suggest why, in the extraction of gold from its ore, there is no need for reduction

Answer 23

Gold is highly unreactive and already occured naturally as an element, hence only purification of the ore is necessary, and nit reduction

Question 24

Properties of iron(iron ore) and (extraction)

Answer 24

Iron ore is a haematite which consists mainly of iron(lll)oxide
Extraction is done in a blast furnace, using coke as a reducing agent.

Question 25

Advantages of iron

Answer 25

When hardened as steel, it is very strong and dense, making it suitable for construction Very abundant and thus very cheap

Question 26

Disadvantages of iron

Answer 26

Iron rusts when exposed to water and air> this can be prevented by using a physical coating or by sacrificial protection Pure iron is too soft for commercial use>can be hardened by adding carbon to form steel

Question 27

Explain in terms of structure, why pure iron is soft when pure

Answer 27

In pure iron, the atoms are arranged in an orderly manner. Hence, when a force is applied to the layer of atoms, the atoms slide over each other easily.

Question 28

Suggest how the addition of carbon helps to strengthen iron

Answer 28

The presence of different sized foreign carbon atoms disrupts the orderly arrangement of iron atoms, hence preventing the layer of iron atoms from sliding over each other as easily

Question 29

Iron extraction in a blast furnace( 1)production of carbon monoxide)

Answer 29

Coke , which consists of carbon, is allowed to combust in air to form carbon dioxide. The combustion provides the heat which is necessary for the subsequent steps to occur Equation:C(s) + O2(g)———CO2(g) The carbon dioxide then reacts with more coke to form carbon monoxide. This reaction can only occur if coke is in excess, causing incomplete combustion to occur. Equation: CO2(g) + C(s)———- 2CO(g) Due to the sulfur impurities in coke, traces of sulfur dioxide may be produced as waste gas, leading to air pollution

Question 30

2) reduction of iron(III) oxide

Answer 30

The carbon monoxide produced reacts with iron(III) oxide in haematite, hence reducing the ore to from molten iron, which settles as a liquid at the bottom of the blast furnace. Equation: Fe2O3(s) + 3CO(g)——- 2 Fe(l) + 3 CO2(g) The molten iron formed contains impurities such as carbon and sulfur. However, it is good enough for industrial use and may be tapped off from the blast furnace to manufacture alloys

Question 31

3)removal of sand impurities

Answer 31

Due to the heat in the blast furnace, limestone(CaCO3) undergoes thermal decomposition to from quicklime(CaO). Carbon dioxide gas is evolved. CaCO3(s)——-CaO(s) + CO2(g) The quicklime then reacts with acidic impurities such as sand to form calcium silicate, known as slag. Slag may be used to from roads. Equation: CaO(s) + SiO2(s)——-CasiO3(l)