Metals And Alloys

Question 1

What is an alloy?

Answer 1

A mixture of a metal and one or more elements, usually other metals or carbon

Question 2

Preventing Rust Formation: Barrier Method

Answer 2

A barrier of paint is placed above the surface of the iron object. Then the oxygen molecules won’t collide with the iron.

Examples of barriers: Painting
Grease/oil
Metals less reactive than iron (e.g chromium)

Question 3

Preventing Rust Formation: Galvanisation

Answer 3

Specifically zinc coating.
Zinc coating is put on the surface of a steel object and then another protective layer of zinc coating is put on top.
Zinc is more reactive than iron.
Zinc reacts/corrodes before iron.
Iron doesn’t oxidize in the reaction.

Question 4

Preventing Rust Formation: Sacrificial Protection

Answer 4

Iron nail wrapped in Magnesium.
Any metal more reactive than iron.
Not completely coating the iron
The iron does not oxidize in the reaction.

Question 5

Oxidation definition 1 and 2

Answer 5

Loss of electrons

Gain of oxygen atoms

Question 6

Reduction definition 1 and 2

Answer 6

Gain of electrons

Loss of oxygen atoms

Question 7

Redox

Answer 7

Electrons lost from one substance must be gained by another substance.

Reduction and Oxidation - REDOX

Question 8

Oxidizing agent

Answer 8

Substance that oxidizes another and itself is reduced in the process.
Always a reactant

Question 9

Reducing agent

Answer 9

Substance that reduced another and is itself oxidized in the process.
Always a reactant

Question 10

Where are most metals extracted from?

Answer 10

Most metals are extracted from ores found in the Earth’s crust
Unreactive metals are often found as the unconvinced elements.

Question 11

How is the method of extraction of a metal related to its place in the reactivity series?

Answer 11

Metals with high reactivity are extracted with electrolysis.
Metals with medium reactivity are extracted by reduction with carbon.
Metals with low reactivity are found pure in nature.

Question 12

The Blast Furnace:

Steps 1 - 4

Answer 12

3 raw materials are added to the top of the furnace: iron ore (haematite), coke (carbon), and limestone (calcium carbonate).
Hot air (2000°C) is blown in the bottom, which causes carbon (coke) to burn, giving out energy. CO2 gas is formed.
C reacts with the CO2 rising up the furnace, forming carbon monoxide.
The CO takes the O2 away from the Fe2O3 to become CO2, making iron metal. It is poured out at the bottom of the furnace - it is a liquid.

Question 13

The Blast Furnace:

Steps 5 - 6

Answer 13

The limestone (calcium carbonate) takes in heat and begins to thermally decompose into calcium oxide and carbon dioxide.

The Calcium oxide reacts with any impurities in iron (mainly sand - silicon dioxide SiO2) forming slag (calcium silicate CaSiO2) which sits on top of the molten iron. The slag is scraped off and used as a foundation for roads.

Question 14

Why are alloys harder than pure metals?

Answer 14

Alloys have different sized atoms, so they don’t slide over each other easily when a force is applied.

Question 15

Explain the electron static attraction

Answer 15

The electrostatic attraction between positively charged metal ions (cations) and a sea of negatively charged delocalized electrons.

Question 16

Physical Properties:

Conduct Electricity

Answer 16

Electricity -> moving electrons -> current

Delocalized electrons are able to move when a voltage is applied.

Question 17

Physical Properties:

Malleable

Answer 17

Can be shaped by hammering, without breaking.
When a force is applied, the rows of cations slide over on another without breaking the metallic bond/attraction between cations and delocalized electrons.

Question 18

Physical Properties:

Ductile

Answer 18

Can be pulled/stretched into a wire without being damaged.

When a force is applied, the rows of cations slide over one another into a line.

Question 19

Aluminium

Answer 19

Used in planes, electricity cables, pots and pans.
Aluminum resists corrosion because it has a very thin but very strong layer of aluminum oxide on the surface. This prevents anything from reaching the surface and reacting with it.

Question 20

High-carbon

Answer 20

Is harder and more resistant to wear than mild steel but more brittle (not as malleable and ductile).
Used for cutting tools.

Question 21

Mild-Steel

Answer 21

A strong material that is malleable and ductile.

It is used in nails, car bodies, ship building and bridges.

Question 22

Copper

Answer 22

Used in electrical wires - good conductor of electricity
Pots and pans - good conductor of heat
Water pipes - unreactive and malleable
Surfaces in hospitals - antimicrobial materials and malleable

Question 23

Electrolysis

Answer 23

High reactivity metals are extracted using electricity.

The ions must be able to move. It must be a liquid.