Metals

Question 1

Properties of metals

Answer 1

• Usually solid at room temp (high melting and boiling points
• Shiny and easily workable
• GOOD CONDUCTORS OF ELECTRICITY AND HEAT
• Form positive ions in their compounds
• HAVE OXIDES THAT ARE USUALLY BASIC, reacting with acids to give a salt and a water

Question 2

Properties of non-metals

Answer 2

• Low melting and boiling points (except silicon and carbon)
• Brittle as solids, not the same shine as in metals
• DON’T USUALLY CONDUCT ELECECTRICITY (EXCEPT SILICON AND CARBON)
• POOR CONDUCTORS OF HEAT
• Tend to form negative ions and covalent compounds
• HAVE OXIDES WHICH ARE ACIDIC OR NEUTRAL

Question 3

Reactivity series of metals

Answer 3

• Potassium
• Sodium
• Lithium
• Calcium
• Magnesium
• Aluminium
• (Carbon)
• Zinc
• Iron
• (Hydrogen)
• Copper
• Silver
• Gold

Question 4

Metallic crystals

Answer 4

Metals have a giant, 3D lattice structure where positive ions are arranged in a regular pattern in a ‘sea of electrons’.

• The outer shell (valence) electrons are detached from the atoms and are DELOCALISED/ spread out throughout the structure.
• They are good conductors of electricity because the delocalised electrons are free to move when voltage is applied to the metal.
• They are malleable and ductile- the layers of positive ions slide over one another and take up different positions (electrons move with them so bonds aren’t broken)

Question 5

Extraction of metals

Answer 5

How a metal is extracted partly depends on its position in the reactivity series.

Question 6

Extraction: Metals less reactive than zinc

Answer 6

IRON AND COPPER
The cheapest way of reducing the ore is to heat it with carbon or carbon monoxide. Carbon is cheap and can also be used as a source of heat, as with iron in a blast furnace.

Question 7

Extraction: Metals more reactive than zinc

Answer 7

They are usually produced by electrolysis, where metals’ ions are given electrons at the cathode. This is expensive, so metals like aluminium are more expensive than iron.

Question 8

Extraction- other methods

Answer 8

Some metals like titanium are extracted by heating the compound with a more reactive metal. This is also expensive as you need the reactive metal to be extracted as well.

Question 9

The rusting of iron

Answer 9

Iron rusts with oxygen and water, and is accelerated by electrolytes such as salt.

Question 10

Rust

Answer 10

Fe2O3·nH2O, where n is a variable number. It behaves as a mixture of iron (lll) oxide and water.

Question 11

Preventing iron from rusting: Barriers

Answer 11

-Paint/ oil/ grease coating
-Covering it in paint
PROBLEM: Once the coating breaks, it rusts.

Question 12

Preventing iron from rusting: Alloying iron

Answer 12

Mixing iron with chromium and nickel to make stainless steel.
It is expensive but effective.

Question 13

Preventing iron from rusting: Sacrificial metals

Answer 13

It can be coated with zinc to make galvanised iron, because zinc is more expensive so it corrodes instead. Zinc loses electrons in this process and they go to the iron- if it can’t form ions, it can’t rust!
Zn(s) –> Zn2+ + 2e-

Question 14

Extraction of iron from iron ore in a blast furnace: Materials to go in

Answer 14

Iron ore, coke (impure carbon) and limestone goes in, called charge. The limestone (CaCO3 is there to remove impurities.

Question 15

C + O2 –> CO2

Answer 15

To make Carbon dioxide, which is needed later, and to generate heat- it is a very exothermic reaction. The oxygen comes from the hot air blasted in.

Question 16

CO2 + C –> 2CO (reducing CO2)

Answer 16

To generate the reducing agent of CO2, Carbon monoxide

Question 17

Fe2O3 + 3CO –> 2Fe + 3CO2

Answer 17

To make iron in a redox reaction. The carbon dioxide is then recycled to the top of the blast furnace.

Question 18

Cast iron

Answer 18

4% carbon, brittle and very hard

Used for manhole covers, guttering and drainpipes and cylinder blocks in car engines.

Question 19

Mild iron

Answer 19

0.25% carbon, hard and strong

Used for wire, nails, car bodies, ship building, girders and bridges

Question 20

Wrought iron

Answer 20

Pure iron, soft and weak

Used to be used for decorative gates and railings. Never structural.

Question 21

High-carbon steel

Answer 21

1.5% carbon, brittle and hard

Used for masonry nails

Question 22

Stainless steel

Answer 22

An alloy with chromium and nickel to form strong oxide layers, resistant to corrosion.

Question 23

Extraction of aluminium from purified aluminium oxide

Answer 23

Because aluminium is fairly reactive, it is extracted using electrolysis. Aluminium oxide has a very high melting point and it isn’t practical to electrolyse molten aluminium oxide. Instead, it is dissolved in molten CRYOLITE. Cryolite is another aluminium compound that melts at a more reasonable temperature, around 1000C

Question 24

Extraction of aluminium from purified aluminium oxide: Conditions

Answer 24

The cell operates at about 5-6 volts but with 100,000 amps. The heat generated by the current keep the electrolyte molten. The anodes have to be replaced regularly because at the high temperature the carbon anodes react and form CO2.

Question 25

Extraction of aluminium from purified aluminium oxide: Cell

Answer 25

There is a carbon lining the container as the cathode.
There are carbon anodes as rods.
The steel tank is lined to be heat resistant.
Molten aluminium collects at the bottom, at the cathode.

Question 26

Extraction of aluminium from purified aluminium oxide: Equations

Answer 26

CATHODE: Al3+(l) + 3e- –> Al(l)
ANODE: 2O2-(l) –> O2(g) + 4e-

Question 27

Aluminium

Answer 27

It is not very strong so alloys are usually used instead, like silicon, copper or magnesium. It is low density, strong (when alloyed), a conductor of electricity and heat, shiny appearance and has an ability to resist corrosion.
It is used in wire cables, saucepans and engines.

Question 28

Burning Magnesium

Answer 28

2Mg(s) + O2(g) –> 2MgO(s)
Bright white flame- though brighter in pure O2.
Makes a white, powdery ash of magnesium oxide.

Question 29

Metals reactions with water/ steam

Answer 29

Metals above hydrogen in the reactivity series react with water or steam to produce hydrogen. Metals below hydrogen don’t react.

Question 30

Metals with steam

Answer 30

Metal + Steam –> Metal oxide + Hydrogen

Question 31

Metals with cold water

Answer 31

Metal + Cold water –> Metal hydroxide + Hydrogen

Question 32

Water with Sodium, Potassium and Lithium

Answer 32

Sodium, Potassium and Lithium are alkali metals so fizz on top of the surface of the water violently.
2x(s) + 2H2O(l) –> 2xOH(aq) + H2(aq)

Question 33

Water with Calcium

Answer 33

Calcium reacts gently, a warm mixture forming an insoluble Calcium hydroxide.
Ca(s) + 2H2O(l) –> Ca(OH)2 + H2(g)

Question 34

Steam with Magnesium

Answer 34

There is almost no reaction here, Magnesium becomes coated with insoluble Magnesium hydroxide when it is with steam in a boiling tube and mineral wool soaked in water.
Mg(s) + H2O(g) –> MgO(s) + H2(g)

Question 35

Steam with Zinc and Iron

Answer 35

Zinc and Iron reacts with steam, slowly producing hydrogen that can be collected.
Zn(s) + H2O(g) –> ZnO(s) + H2(g)
3Fe(s) + H2O(g) –> Fe3O4(s) + 4H2(g)

Question 36

Metal Oxide

Answer 36

Acid + Metal Oxide –> Salt + Water

Metal (above hydrogen) + Steam –> Metal Oxide + Hydrogen

• Mostly insoluble in water and they don’t react
• Though a very small amount does react with water and forms a slightly alkaline solution

Question 37

Metal Hydroxide

Answer 37

Acid + Metal Hydroxide –> Salt + Water

Metal (above hydrogen) + Cold water –> Metal Hydroxide + Hydrogen

Question 38

Metal Carbonate

Answer 38

Acid + Metal Carbonate –> Salt + Water + Carbon Dioxide