Metals And Redox

Question 1

Which metals react very slowly with cold water but react when heated in steam to produce an insoluble metal oxide and hydrogen?

Answer 1

Magnesium, aluminium, zinc, iron

Question 2

Which metals do not react with water or steam?

Answer 2

Copper, silver, gold

Question 3

What is an ore?

Answer 3

A mineral containing a metal compound from which the metal can be economically extracted

Question 4

When is a metal compound not an ore?

Answer 4

Aluminium is the most abundant element in the earths crust and it is extracted from bauxite, impure aluminium oxide, soil also contains aluminium compounds however it would be much more expensive to extract it from so bauxite is an aluminium ore but soil is not

Question 5

What are the three stages involved in metal extraction?

Answer 5

• Mining the metal ore and concentrating it
• Conversion of the metal ore into metal
• Purification of the metal

Question 6

How is ease of reduction related to the position of the metal in the reactivity series?

Answer 6

Oxides of metals high in reactivity are harder to reduce

Oxides of metals low in reactivity are easier to reduce

Question 7

What are the methods used to reduce metals?

Answer 7

• A more reactive metal
• Carbon
• Carbon monoxide
• Electricity

Question 8

What is coke?

Answer 8

Heat treated coal

Question 9

What is the main ore of iron?

Answer 9

Haematite

Question 10

What are the four raw materials/substances that do in to the blast furnace?

Answer 10

• Iron ore (Fe2O3)
• Coke (C)
• Limestone (CaCO3)
• Air (O2)

Question 11

What 3 substances come out of the blast furnace?

Answer 11

• Molten iron
• Molten slag
• Waste gases

Question 12

What reaction provides the heat in the blast furnace?

Answer 12

C + O2 -> CO2

Question 13

What is the reaction where carbon dioxide is reduced by coke?

Answer 13

CO2 + C -> CO

Question 14

What is the reaction that decomposes limestone?

Answer 14

CaCO3 -> CaO + CO2

Question 15

What is the reaction that reduces Haematite

Answer 15

Fe2O3 + 3CO -> 2Fe + 3CO2

Question 16

What reaction removes impurities from molten iron?

Answer 16

(CaCO3 -> CaO + CO2 (if asked for 2 reactions))

CaO + SiO2 -> CaSiO3

Question 17

What gases are in the waste gases produced in a blast furnace?

Answer 17

Mainly nitrogen, with carbon monoxide and carbon dioxide

Question 18

What is molten slag used for in a blast furnace?

Answer 18

It prevents re oxidation of the iron by the air (it is less dense and so can also be tapped out separately)

Question 19

What is an alloy?

Answer 19

A mixture of metals or of a metal and carbon

Question 20

What substances are needed for iron to rust?

Answer 20

Water and oxygen

Question 21

What is rust?

Answer 21

Hydrated iron oxide (Fe2O3)

Question 22

What are 3 ways of rust prevention?

Answer 22

• Paint
• Grease/Oil
• Plastic

Question 23

What is sacrificial protection?

Answer 23

Attaching a block of metal that is more reactive than iron, to the iron, zinc is often used. The more reactive metal will corrode before the iron

Question 24

What is galvanising?

Answer 24

Dipping iron into molten zinc so the iron is completely coated, used on dustbins and buckets for example. However tin is used for food containers, such as tin cans

Question 25

What are the main properties of transition metals?

Answer 25

- They all show variable valences - They form coloured compounds - They and their compounds are used as catalysts - They have high melting points, boiling points and densities (except Mercury) - They have high tensile strengths which makes them structurally useful

Question 26

What is the name and formula of aluminium ore?

Answer 26

Bauxite, Al2O3

Question 27

What are the anode and cathode made of?

Answer 27

Carbon, in the form of graphite

Question 28

What is the equation at the cathode?

Answer 28

Al3+ + 3e− → Al

Question 29

What's the equation at the anode?

Answer 29

2O2− → O2 + 4e−

Question 30

Why does the anode require frequent replacement?

Answer 30

At the operating temperature of about 1000°C, the graphite anodes burn away in the oxygen to give carbon dioxide.

Question 31

Which metals react with cold water to give soluble metal hydroxide and hydrogen?

Answer 31

Potassium, sodium, lithium, calcium

Question 32

What is the other substance present in manufacture/extraction of aluminium?

Answer 32

Cryolite- it is added to reduce the operating temperature, once molten it acts as a solvent for aluminium oxide, reducing the operating temperature from around 2000°c to 800°c

Question 33

Why is aluminium not extracted in the same way as iron?

Answer 33

Iron ore is less reactive so it can be extracted with carbon, however aluminium is more reactive than carbon and so cannot be reduced by it

Question 34

Why is iron not extracted by electrolysis?

Answer 34

Because reduction is a cheaper way of extracting iron and it would be unnecessary to use electrolysis

Question 35

What are the main properties of aluminium?

Answer 35

- Conducts electricity well - Conducts heat well - Alloys have low density (most important property) - Does not corrode - Malleable - Lustrous