C10 - Metals Flashcards

1
Q

Properties of metals (name 3)

A
  • Conduct heat and electricity
  • Are malleable (can be hammered and made into different shapes) and ductile (can be drawn into wires)
  • Tend to be lustrous (shiny)
  • Have high density and usually have high melting points
  • Form positive ions through electron loss
  • Form basic oxides
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2
Q

Properties of non-metals (name 3)

A
  • Do not conduct heat and electricity
  • Are brittle when solid and easily break up
  • Tend to be dull and nonreflective
  • Have low density and low melting points (many are gases at room temperature)
  • Form negative ions through electron gain (except for hydrogen)
  • Form acidic oxides
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3
Q

Metal and water reaction

A

metal + water → metal hydroxide + hydrogen

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4
Q

Metal and acid reaction

A

metal + acid → salt + hydrogen

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5
Q

Metal and oxygen reaction

A
  • Unreactive metals do not react with oxygen
  • Some reactive metals like alkali easily can
  • Copper and iron can also react but slowly

metal + oxygen → metal oxide

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6
Q

Uses of aluminium and their reason (name 3)

A
  • Aeroplane bodies
    • high strength-to-weight ratio, low density
  • Overhead power cables
    • good conductor of electricity, low density
  • Saucepand
    • good conductor of heat
  • Food cans
    • non-toxic, resistant to corrosion and acidic food stuffs
  • Window frames
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7
Q

Uses of copper and their reason (2)

A
  • Electrical wire
    • good conductor of electricity and malleable
  • Water piper
    • easy to work with and bent, non-toxic and unreactive with water
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8
Q

Alloy

A

A mixture of two or more metals or metal with a non-metal such as carbon

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9
Q

Metallic bonding

A

Metal atoms are held together strongly by metallic bonding in a giant metallic lattice wih delocalised electrons
* allows electrical conduction
* ductility and malleability as layers of atoms allows them to slide over each other

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10
Q

Brass (use)

A

An alloy of copper and zinc and is much stronger than either metal
* It is used in musical instruments, ornaments and door knobs

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11
Q

Stainless steel

A

Stainless steel is a mixture of iron and other elements, for example, chromium, nickel and carbon
* It is used in cutlery because of its hardness and resistance to corrosion

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12
Q

Why are metal alloys used more than pure metals?

A
  • Alloys often have properties that can be very different from the metals they contain, for example, they can have more strength, hardness or resistance to corrosion or extreme temperatures
  • These enhanced properties can make alloys more useful than pure metals
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13
Q

Iron and tungsten alloys (qualities)

A

Extremely hard and resistant to high temperatures

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14
Q

Iron and chromium or nickel alloy (qualities)

A

Resistant to corrosion

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15
Q

Reactivity series (from most to least reactive)

A
  • Potassium
  • Sodium
  • Calcium
  • Magnesium
  • Aluminium
  • Carbon
  • Zinc
  • Iron
  • Hydrogen
  • Copper
  • Silver
  • Gold
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16
Q

Reaction with cold water - metals in the reactivity series

A
  • More reactive metals will react with cold water to form metal hydroxide and hydrogen gas
    • these are potassium, sodium and calcium
17
Q

Reaction with steam - metals in the reactivity series

A

Only metals below calcium in the reactivity series do not react with cold water but will react with steam to form a metal oxide and hydrogen gas

18
Q

Reaction with dilute acids - metals in the reactivity series

A
  • Only metals above hydrogen in the reactivity series will react with dilute acids
  • High metals (potassium, sodium) react explosively to acids
  • General equation: metal + acid ⟶ salt + hydrogen
19
Q

Reaction with oxygen - metals in the reactivity series

A
  • Some reactive metals, such as the alkali metals, react easily with oxygen
  • Silver, copper and iron can also react with oxygen although much more slowly
  • Gold does not react
  • When metals react with oxygen a metal oxide is formed
20
Q

Displacement reaction

A

One in which a more reactive metal displaces a less reactive metal from a compound
* usually to form a salt and a metal

21
Q

Extraction of metals above carbon in the reactivity series

A
  • Extracted by electrolysis of the molten chloride or molten oxide
22
Q

Extraction of metals below carbon in the reactivity series

A
  • Extracted by heating with a reducing agent such as carbon monoxide in a blast furnace
  • They are found as pure elements
23
Q

Describe the process of extraction of iron from hematite (8 steps)

A
  1. Raw materials iron ore (hematite), coke (impure form of carbon) and limestone are added into the top of the blast furnace
  2. Hot air is blown into the bottom
  3. At the bottom of the furnace:
    1. Coke burns in the hot air forming carbon dioxide
    2. Exothermic reaction heats the furnace: carbon + oxygen -› carbon dioxide
  4. Middle of the furnace:
    1. At the high temperatures in the furnace, more coke reacts with carbon dioxide forming carbon monoxide
    2. Carbon dioxide has been reduced to carbon monoxide: carbon + carbon dioxide -› carbon monoxide
  5. Top of the furnace:
    1. Carbon monoxide reduces the iron(III) oxide in the iron ore to form iron
    2. This will melt and collect at the bottom of the furnace, where it is tapped off: iron (III) oxide + carbon monoxide -› iron + carbon dioxide
  6. Limestone is added to the furnace to remove impurities because calcium cabonate in limestone thermally decomposes to form calcium oxide
  7. The calcium oxide formed reacts with the silicon dioxide, which is an impurity in the iron ore, to form calcium silicate
  8. This melts and collects as a molten slag floating on top of the molten iron, which is tapped off separately
24
Q

Equation for zone 1 in iron extraction

A

The burning of carbon (coke) to provide heat and produce carbon dioxide:
C (s) + O2 (g) → CO2 (g)

25
Q

Equation for zone 2 in iron extraction

A

The reduction of carbon dioxide to carbon monoxide:
CO2 (g) + C (s) → 2CO (g)

26
Q

Equation for zone 3 in iron extraction

A

The reduction of iron(III) oxide by carbon monoxide:
Fe2O3 (s) + 3CO (g) → 2Fe (I) + 3CO2 (g)

27
Q

Equation for limestone in iron extraction

A

The thermal decomposition of calcium carbonate (limestone) to produce calcium oxide:
CaCO3 (s) → CaO (s) + CO2 (g)

28
Q

Equation for formation of slag in iron extraction

A

CaO (s) + SiO2 (s) → CaSiO3 (l) (calcium silicate)

29
Q

Main ore of aluminium

A

bauxite

30
Q

Process of extraction of aluminium from bauxite (5 steps)

A
  1. Bauxite is purified to produce aluminium oxide (Al2O3)
  2. Aluminium oxide is the dissolved in molten cryolite
    1. this is because aluminium oxide has a melting point of over 2000°C which would use a lot of energy and be very expensive so they lower the melting point
  3. The mixture is placed in an electrolysis cell made from steel, lines with graphite
    1. The graphite lining acts as the negative electrode, with several large graphite blocks as the positive electrodes
  4. At the cathode:
    1. Aluminium gains electrons and molten aluminium forms at the bottom of the cell and then is siphoned off from time to time as fresh aluminium is added: Al3+ + 3e- → Al
  5. At the cathode:
    1. Oxide ions lose electrons and oxygen is produced: 2O2- → O2 + 4e-
31
Q

Why does the graphite anode have to be replaced regularly in aluminium extraction?

A

The carbon in the graphite anodes reacts with the oxygen produced to produce CO2: C (s) + O2 (g) → CO2 (g)
* As a result the anode wears away and has to be replaced regularly

32
Q

Galvanising

A

Galvanising is a process where the iron to be protected is coated with a layer of zinc
* This can be done by electroplating or dipping it into molten zinc

33
Q

Sacrificial protection

A

A more reactive metal can be attached to a less reactive metal
* The more reactive metal will oxidise and therefore corrode first, protecting the less reactive metal from corrosion