Metals And Redox Flashcards

1
Q

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

A

Magnesium, aluminium, zinc, iron

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2
Q

Which metals do not react with water or steam?

A

Copper, silver, gold

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3
Q

What is an ore?

A

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

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4
Q

When is a metal compound not an ore?

A

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

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5
Q

What are the three stages involved in metal extraction?

A
  • Mining the metal ore and concentrating it
  • Conversion of the metal ore into metal
  • Purification of the metal
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6
Q

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

A

Oxides of metals high in reactivity are harder to reduce

Oxides of metals low in reactivity are easier to reduce

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7
Q

What are the methods used to reduce metals?

A
  • A more reactive metal
  • Carbon
  • Carbon monoxide
  • Electricity
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8
Q

What is coke?

A

Heat treated coal

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9
Q

What is the main ore of iron?

A

Haematite

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10
Q

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

A
  • Iron ore (Fe2O3)
  • Coke (C)
  • Limestone (CaCO3)
  • Air (O2)
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11
Q

What 3 substances come out of the blast furnace?

A
  • Molten iron
  • Molten slag
  • Waste gases
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12
Q

What reaction provides the heat in the blast furnace?

A

C + O2 -> CO2

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13
Q

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

A

CO2 + C -> CO

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14
Q

What is the reaction that decomposes limestone?

A

CaCO3 -> CaO + CO2

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15
Q

What is the reaction that reduces Haematite

A

Fe2O3 + 3CO -> 2Fe + 3CO2

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16
Q

What reaction removes impurities from molten iron?

A

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

CaO + SiO2 -> CaSiO3

17
Q

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

A

Mainly nitrogen, with carbon monoxide and carbon dioxide

18
Q

What is molten slag used for in a blast furnace?

A

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

19
Q

What is an alloy?

A

A mixture of metals or of a metal and carbon

20
Q

What substances are needed for iron to rust?

A

Water and oxygen

21
Q

What is rust?

A

Hydrated iron oxide (Fe2O3)

22
Q

What are 3 ways of rust prevention?

A
  • Paint
  • Grease/Oil
  • Plastic
23
Q

What is sacrificial protection?

A

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

24
Q

What is galvanising?

A

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

25
Q

What are the main properties of transition metals?

A
  • 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
26
Q

What is the name and formula of aluminium ore?

A

Bauxite, Al2O3

27
Q

What are the anode and cathode made of?

A

Carbon, in the form of graphite

28
Q

What is the equation at the cathode?

A

Al3+ + 3e− → Al

29
Q

What’s the equation at the anode?

A

2O2− → O2 + 4e−

30
Q

Why does the anode require frequent replacement?

A

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

31
Q

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

A

Potassium, sodium, lithium, calcium

32
Q

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

A

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

33
Q

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

A

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

34
Q

Why is iron not extracted by electrolysis?

A

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

35
Q

What are the main properties of aluminium?

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