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Chemistry IGCSE > Unit 9 - Metals > Flashcards

Unit 9 - Metals Flashcards

1
Q

Reason for electrical conductivity in metals

A

Presence of delocalized electrons which can conduct electricity

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2
Q

Reason for thermal conductivity in metals

A

High density makes heat easier to pass through particles via vibrations

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3
Q

Reason for high melting and boiling points in metals

A

Strong forces of attraction need high temperatures to break bonds

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4
Q

Malleability

A

The ability to shape a substance

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5
Q

Ductility

A

The ability to pull a substance into stretched out wires

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6
Q

Reason for malleability and ductility in metals

A

Metals are arranged in layers with delocalized electrons that allow them to slide past each other easily

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7
Q

Reactions with metals and dilute acids

A

Metal + Acid –> Salt + Hydrogen

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8
Q

Reactions with metals and water

A

Metal + Water –> Metal hydroxide + Hydrogen

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9
Q

Reactions with metal and oxygen

A

Metal + Oxygen –> Metal oxide

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10
Q

Aluminum features

A
  • Exceptionally low density but relatively strong
  • Conducts electricity
  • Corrosion resistant
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11
Q

Uses of aluminum

A
  • Aircrafts - strong but low density
  • Overhead cables - good conductor, low density
  • Storing food - corrosion resistant
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12
Q

Uses of copper

A
  • Wiring - high conductivity, very ductile, flexible
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13
Q

Alloys

A

Mixture of a metal and another element - tend to be stronger and harder than pure metals

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14
Q

Bronze composition

A

Tin and copper

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15
Q

Brass composition

A

Copper and zinc - causes it to be corrosion resistant and gold color

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16
Q

Steel composition

A

Group of alloys made with iron

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17
Q

Uses of steel

A
  • Car engines
  • Drill bits
  • Cutting tools
18
Q

Stainless steel composition

A
  • Iron mixed with carbon and other metals e.g. chromium and nickel - protects rusting
19
Q

Uses of stainless steel

A
  • Cutlery
  • Specialist equipment that process corrosive substances in chemical industry
20
Q

Reasons for alloys’ lack of malleability and ductility

A

The admixture of particles of different sized causes the layers to not be able to slide/ interlocks them

21
Q

Order of reactivity series

A

1.Potassium - K
2.Sodium - Na
3.Calcium - Ca
4.Magnesium - Mg
5.Aluminum - Al
6.Carbon - C
7.Zinc - Zn
8.Iron - Fe
9.Hydrogen - H
10.Copper - Cu
11.Silver - Ag
12.Gold - Au

22
Q

Elements of the reactivity series and their reaction with water

A
  • Aluminum and below don’t react
  • Magnesium only reacts with steam
  • Calcium reacts strongly
  • Sodium reacts vigorously/violently
  • Potassium reacts the most vigorous/violent
23
Q

Elements of the reactivity series and their reactions with dilute HCl

A
  • Magnesium - strong, forms bubbles quickly
  • Zinc - bubbles form slowly
    -Iron - Very slow, must be powdered iron
  • Rest don’t react
24
Q

Displacement reaction

A

When a more reactive element takes the place of a less reactive element in a compound

25
Q

Relationship with the reactivity of a metal and its ions

A
  • The more reactive the metal, the less reactive the ions
  • The less reactive the metal, the more reactive the ions
26
Q

Reason for aluminum being corrosion resistant

A

When aluminum is exposed to air, it creates a microscopic layer that is a perfect barrier around the metal and prevents corrosion

27
Q

Corrosion

A

Caused by metal reactions with oxygen

28
Q

Rusting

A

The oxidation of iron

29
Q

Rust chemical equation

A
  • Iron + Water + Oxygen –> Hydrated iron(III) oxide
    -2Fe(s) + 2H2O(l) + O2(g) –> Fe2O3·H2O(s)
30
Q

Barrier methods for corrosion prevention

A
  • Painting - Protects and colors
  • Plastic coating - Protects and colors with thick-polymer based coating
  • Lubricants - e.g. grease or oil - prevent corrosion and reduce friction to assist movement
  • Electroplating
31
Q

Sacrificial protection

A

Covering a metal like Iron with a more reactive metal e.g. zinc, magnesium, aluminum - more reactive metal would lose electrons that would prevent iron from oxidizing

32
Q

Galvanizing

A
  • Uses barrier method and sacrificial protection
  • Coated in a thin layer of zinc + barrier e.g. paint
33
Q

Hematite

A

Iron ore

34
Q

Bauxite

A

Aluminum ore

35
Q

Extraction of Iron

A

1.Carbon + oxygen –> carbon dioxide - hot air blasted in, complete combustion of carbon
2.Carbon dioxide + carbon –> carbon monoxide - oxygen gets used as hot air moves into the furnace, carbon dioxide reacts with coke, incomplete combustion of carbon makes carbon monoxide gas
3.Iron(III) oxide + carbon monoxide –> iron + carbon dioxide - carbon monoxide moves higher and reacts with iron (III) oxide, iron ions in iron(III) oxide are reduced to molten iron and is collected

36
Q

Reducing impurities of Carbon

A

Carbon + oxygen –> carbon dioxide - most coke is combusted and can dissolve into the liquid iron, carbon reacts with oxygen and carbon dioxide gas is released and flows out the blast furnace

37
Q

Reducing impurities of Sulfur

A

Sulfur + oxygen –> sulfur dioxide -
Sulfur impurities react with oxygen in air blast to form Sulfur dioxide which flows out the blast furnace

38
Q

Reducing impurities of Silicon

A

1.Calcium carbonate –> calcium oxide + carbon dioxide - calcium carbonate in limestone thermally decomposes to become more reactive than calcium oxide
2.Calcium oxide + silicon dioxide –> slag - acidic impurity, calcium oxide and silicon dioxide react to make molten liquid slag, less dense and floats to top of liquid iron to collect at the bottom

39
Q

Problems with Aluminum electrolysis

A
  • Aluminum is more reactive than hydrogen - can’t be electrolyzed from an aqueous solution
  • Melting point of aluminum oxide is too high
40
Q

How to overcome problems with aluminum electrolysis

A
  • Aluminum oxide is dissolved into a salt - cryolite
  • Cryolite - doesn’t have any elements less reactive than aluminum or oxygen and has a high melting point but lower than aluminum oxide
  • Cryolite heated to molten and then aluminum oxide added
  • Dissolved solution has a melting point of 900-1000˚C
  • Steel bath can be used due to lower melting point
  • Anode and cathode made of graphite - good conductor
  • Oxygen reacts with carbon anode to make CO2
    -Molten aluminum is denser and sinks to the bottom to be removed and collected
41
Q

Chemical half equations for aluminum oxide electrolysis

A
  • Anode: 2O^-2 –> O2 + 4e^- oxide ion loses electrons - oxidized
  • oxygen gas produced reacts with graphite anode: O2 + C –> CO2
  • Cathode: Al^3+ + 3e^- –> Al aluminum ion gaining electrons and is being reduced
42
Q

Overall balanced equation of aluminum oxide electrolysis

A

2Al2O3(l) –> 4Al(l) + 3O2(g)

Chemistry IGCSE (7 decks)

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