metals

Question 1

List the general physical properties of metals

Answer 1

Question 2

Diagram showing bonding and structure in metals

Answer 2

Question 3

General chemical properties of Metals

Answer 3

The chemistry of metals is studied by analysing their reactions with water, dilute acid and oxygen.

Based on these reactions a reactivity series
of metals can be produced.

Question 4

Reactivity with water

Answer 4

Some metals react with water, either warm or cold, or with steam.

Metals that react with cold water form a metal hydroxide and hydrogen gas, for example calcium:

Question 5

Reactivity with acids

Answer 5

Most metals react with dilute acids such as HCl.

When acids and metals react, the hydrogen atom in the acid is replaced by the metal atom to produce a salt and hydrogen gas, for example iron:

Question 6

Reactivity with oxygen

Answer 6

Unreactive metals such as gold and copper do not react with acids.

Some reactive metals such as the alkali metals react with oxygen.

Copper and iron can also react with oxygen although much more slowly.

When metals react with oxygen a metal oxide is formed, for example copper:

Question 7

Alloys

Answer 7

An alloy
is a mixture of two or more metals or a metal and a nonmetal.

Alloys often have properties that can be very different to the metals they contain, for example can have more strength, hardness or resistance to corrosion or extreme temperatures.

Alloys contain atoms of different sizes, which distorts normally regular arrangements of atoms in metals.

This makes it more difficult for the layers to slide over each other, so alloys are usually much harder than the pure metal.

Question 8

Alloys arrangement of a metal lattice structure

Answer 8

Question 9

Alloys are mixtures of…

They are not …combined.

An alloy is not a…

Answer 9

• substances.
• chemically
• compound.

Question 10

Common alloys and their uses

Answer 10

Brass is an alloy of copper and zinc and is much stronger than either metal.

Alloys of iron with tungsten are extremely hard and resistant to high temperatures.

Alloys of iron mixed with chromium or nickel are resistant to corrosion.

Aluminium is mixed with copper, manganese and silicon for aircraft body production as the alloy is stronger but still has a low density.

Question 11

The Reactivity Series

Answer 11

The chemistry of the metals is studied by analysing their reactions with water, dilute acid and oxygen.

Based on these reactions a reactivity series of metals can be produced.

The series can be used to place a group of metals in order of reactivity based on the observations of their reactions with water, acid and oxygen.

Question 12

The reactivity series mnemonic

Answer 12

“Please send lions, cats, monkeys and cute zebras into hot countries signed Gordon”.

Question 13

Displacement reactions between metals and metal oxides

Answer 13

The reactivity of metals increases going up the reactivity series.

This means that a more reactive metal can displace a less reactive metal from its oxide by heating.

Example: Copper(II) Oxide

It is possible to reduce copper(II) oxide by heating it with magnesium.

As magnesium is above copper in the reactivity series, magnesium is more reactive so can displace copper.

The reducing agent in the reaction is magnesium:

Question 14

they are all

Answer 14

Displacement reactions between metals and metal oxides

Question 15

Answer 15

Question 16

Displacement reactions between metals and aqueous solutions of metal salts

Answer 16

Any metal will displace another metal that is below it in the reactivity series from a solution of one of its salts.

This is because more reactive metals lose electrons and form ions more readily than less reactive metals, making them better reducing agents.

The less reactive metal is a better electron acceptor than the more reactive metal, thus the less reactive metal is reduced. (OIL-RIG: reduction is gain of electrons).

Question 17

expalin example and write an equation for it

Example: Zinc and copper(II) sulfate

Answer 17

As Zinc is above copper in the reactivity series, zinc is more reactive so can displace copper from copper(II) sulfate solution:

Question 18

these are all…

Answer 18

Displacement reactions between metals and aqueous solutions of metal salts

Question 19

Thermal decomposition reactions

Answer 19

Some compounds decompose or breakdown when they are heated to sufficiently high temperatures.

These reactions are called thermal decomposition reactions.

A common example is the thermal decomposition of calcium carbonate (limestone), which occurs at temperatures above 800ºC:

Question 20

Thermal decomposition of metal hydroxides

Answer 20

Most metal hydroxides undergo thermal decomposition.

Water and the corresponding metal oxide are the products formed, for example zinc hydroxide thermally decomposes as follows:

Group II metal hydroxides decompose similarly but the Group I hydroxides (apart from lithium) do not decompose due to their having a higher thermal stability.

Question 21

Thermal decomposition of metal carbonates

Answer 21

Most of the metal carbonates and hydrogen carbonates undergo thermal decomposition.

The metal oxide and carbon dioxide are the products formed, for example magnesium carbonate thermally decomposes as follows:

Group I carbonates (again apart from lithium carbonate) do not decompose when heated.

This is due to the high thermal stability of reactive metals; the more reactive the metal then the more difficult it is to decompose its carbonate.

CuCO3 for example is relatively easy to thermally decompose but K2CO3 does not decompose.

Question 22

Thermal decomposition of metal nitrates

Answer 22

All of the metal nitrates decompose when they are heated.

Group I nitrates decompose forming the metal nitrite and oxygen, for example sodium nitrate decomposes as follows:

Question 24

Aluminium and its apparent lack of reactivity

Answer 24

Aluminium is a curious metal in terms of its reactivity.

It is placed high on the reactivity series but it doesn’t react with water or acids.

This is because the surface of aluminium metal reacts with oxygen in the air forming a protective coating of aluminium oxide:

Question 25

Extraction of ores from the Earth’s crust

Answer 25

The Earth’s crust contains metals and metal compounds such as gold, iron oxide and aluminium oxide.

When found in the Earth, these are often mixed with other substances.

To be useful, the metals have to be extracted from their ores through processes such as electrolysis, using a blast furnace or by reacting with more reactive material.

The extraction of metals is a reduction process.

Unreactive metals do not have to be extracted as they are often found as the uncombined element as they do not easily react with other substances.

Question 26

Extraction of metal and the reactivity series

Answer 26

The position of the metal on the reactivity series influences the method of extraction.

Those metals placed higher up on the series (above carbon) have to be extracted using electrolysis.

Metals lower down on the series can be extracted by heating with carbon.

Question 27

The extraction of iron in the blast furnace

Answer 27

Question 28

The extraction of iron in the blast furnace

Answer 28

Raw Materials:

Iron Ore (Haematite), Coke, Limestone and Air

Explanation:

Iron Ore, Coke and Limestone are mixed together and fed into the top of the blast furnace. Hot air is blasted into the bottom of the blast furnace

Question 29

Describe the conversion of iron into steel using basic oxides and oxygen

Answer 29

Molten iron is an alloy of 96% iron, with carbon, phosphorus, silicon and sulfur impurities.

It is too brittle for most uses, so most of it is converted into steel by removing some of the impurities.

Not all of the carbon is removed as steel contains some carbon, the percentage of which depends on the use of the steel.

The molten iron is transferred to a tilting furnace where the conversion to steel takes place.

Oxygen and powdered calcium oxide are added to the iron.

The oxygen oxidises the carbon, phosphorus, silicon and sulfur to their oxides which are all acidic.

CO2 and SO2 are gaseous so escape from the furnace.

The acidic silicon and phosphorus oxides react with the powdered calcium oxide and from a slag which is mainly calcium silicate:

SiO2(l) + CaO(s) → CaSiO3(s)

The slag floats on the surface of the molten iron and is removed.

Question 30

Extraction of aluminium

Answer 30

Aluminium is a reactive metal which sits above carbon on the reactivity series.

It cannot be extracted from its ore (bauxite) by carbon reduction, so electrolysis is used.

Question 31

Recycling metals: iron, steel and aluminium

Advantages and disadvantages

Answer 31

Advantages

Raw materials are conserved (bauxite and haematite).

Energy use is reduced, especially in the electrolysis of aluminium.

Less pollution is produced as both processes contribute to air pollution.

Disadvantages

More transport on roads carrying used metals to recycling centres.

Energy consumed in collecting materials and sorting them per material type.

Question 32

The Process of Alumium Extraction by Electrolysis

Answer 32

Diagram Showing the Extraction of Aluminium by Electrolysis

Raw Materials:

Aluminium Ore (Bauxite)

Explanation:

The Bauxite is first purified to produce Aluminium Oxide Al2O3

Aluminium Oxide has a very high melting point so it is first dissolved in molten Cryolite producing an electrolyte with a lower melting point, as well as a better conductor of electricity than molten aluminium oxide. This also reduces expense considerably.

The electrolyte is a solution of aluminium oxide in molten cryolite at a temperature of about 1000 °C. The molten aluminium is siphoned off from time to time and fresh aluminium oxide is added to the cell. The cell operates at 5-6 volts and with a current of 100,000 amps. The heat generated by the huge current keeps the electrolyte molten.

A lot of electricity is required for this process of extraction, this is a major expense.

Question 33

The Process of Alumium Extraction by Electrolysis

Supplement:

Answer 33

Question 34

The Process of Zinc Extraction

Answer 34

Question 35

Uses of Aluminium

use and most important properties in the use

Answer 35

Question 36

Uses of Copper and special properties for uses

Answer 36

Question 37

Uses of Steel and special properties for uses

Answer 37

Question 38

Steel Alloys and Their Properties

Answer 38

The amount of carbon removed depends on the amount of oxygen used.

By carefully controlling the amount of carbon removed and subsequent addition of other metals such as chromium, manganese or nickel, the particular type of steel alloy is produced.

Question 39

Explain the uses of zinc for galvanising and for making brass

Answer 39

Zinc is used in galvanising, the process of coating a metal such as iron or steel with a protective coating of zinc to prevent corrosion or rusting.

Galvanising is an effective way of rust protection as it works even if the zinc coating becomes scratched or damaged.

The process can be done electrolytically or by dipping the metal parts into baths of molten zinc.

Zinc is also used to make an alloy called brass.

Brass contains 70% copper and 30% zinc.

The addition of zinc makes the alloy much harder and corrosion resistant than copper alone.