Metals And Metal Extraction

Question 1

What are alloys

Answer 1

Alloys are a mixture of a metal and another element

They tend to be stronger and harder than pure metals and are therefore much more useful

Question 2

What are the types of alloys and why are they important

Answer 2

Brass - made by mixing copper and zinc. Brass is resistant to corrosion and has an attractive golden colour. These properties allow it to be used to improve the looks of objects that would come into contact with the weather

Steel - alloys made with iron. It is used to make things like car engines because it is both hard and strong.

Question 3

What are redox reaction

Answer 3

Redox reactions are reactions involving simultaneous (existing or occurring at the same time), oxidation (loss of electrons or gain of oxygen) and reduction (gain of electrons or loss of oxygen) reactions

Question 4

Identify redox reactions by changes in oxidation number

Answer 4

An element always has an oxidation state of zero

For a compound the sum of the oxidation state is zero

For an ion, the charge on the ion must equal the sum of the oxidation states

The oxidation number of a monatomic ion is the same as the charge on the ion

Question 5

How do you know if a substance is being oxidized or reduced

Answer 5

During a redox reaction, if the oxidation state of a substance becomes more positive, then oxidation is occurring. If it becomes less positive, than reduction is occurring

Question 6

Define an oxidizing agent

Answer 6

An oxidizing agent is a substance that oxidizes another substance during a redox reaction, while itself is reduce

Question 7

Define a reducing agent

Answer 7

A reducing agent is a substance that reduces another substance during a redox reaction, while itself is oxidized

Question 8

Describe the ease in obtaining metals from their ores

Answer 8

Most metals are too reactive to be found in their metallic state but are instead trapped as ions in ionic compounds in ores

Question 9

How do you extract iron

Answer 9

1. Hematite (iron ore), coke (carbon) and limestone (silicon) is added
2. Solids are preheated
3. Solids are added in carefully controlled proportions
4. Limestone thermally decomposes into calcium oxide
5. Iron(III) oxide reduced to iron
6. Carbon monoxide made
7. Hot air blasted in
8. Removal of slag
9. Molten iron is collected
10. Exhaust gases removed

Question 10

How do you extract aluminum

Answer 10

Aluminium is extracted from an ore called bauxite.

The bauxite processed to remove impurities until aluminium oxide is produced

Aluminium is more reactive than carbon, so it cannot be extracted using the blast furnace, therefore electrolysis is used instead

Question 11

Name how chemical reactions occur in the blast furnace

Answer 11

Combustion of carbon - carbon + oxygen —> carbon dioxide (C + O2 —> CO2)
Production of carbon monoxide - carbon dioxide + carbon —> carbon monoxide (CO2 + C —> 2CO)
Reduction of iron oxide - iron(III) oxide + carbon monoxide —> iron + carbon dioxide (Fe2O3 + 3CO —> 2Fe + 3CO2)
Combustion of sulfur - sulfur + oxygen —> sulfur dioxide (S + O2 —> SO2)
Thermal decomposition of calcium carbonate - calcium carbonate —> calcium oxide + carbon dioxide (CaCO3 —> CaO + CO2)
Formation of slag - calcium oxide + silicon dioxide —> slag (CaO + SiO2 —> CaSiO3)