metals and their extractions

Question 1

what is metal extraction

Answer 1

metals are extracted from ores which are rocks containing metal compounds found in the earths crust

these metals can be extracted using chemical reactions

Question 2

what is the relationship between metal reactivity and extraction

Answer 2

the more reactive the metal is the more stable its metal compound so the harder it is ti extract the pure metal

Question 3

what are the extraction processes depending in the reactivity series

Answer 3

electrolysis - for metals more reactive than carbon

reduction with carbon - for metals less reactive than carbon (cheap process and is favoured over electrolysis)

metals less reactive than hydrogen are found pure in their native form

Question 4

what is a displacement reaction and how is it useful

Answer 4

when a more reactive metal displaces a less reactive metal from a compound

they can be used to investigate the relative reactivities of metals

Question 4

what is oxidation

Answer 4

gain of oxygen

loss of electrons

loss of hydrogen

the species oxidised is known as the reducing agent

Question 5

what is reduction

Answer 5

loss of oxygen

gain of electrons

gain of hydrogen

the species reduced is known as the oxidising agent

Question 6

what are the reactions involved in the extraction of iron in a blast furnace

Answer 6

the process is a reduction process

coke reacts with oxygen in the air to form carbon dioxide (exothermic combustion reaction)

C + O2 —> CO2

the carbon dioxide reacts with more coke to form carbon monoxide (the carbon is reduced)

CO2 + C —>2CO

the iron oxide reacts with the coke or carbon monoxide and is reduced to form molten iron

3CO + FE2O3 —>3CO2 +2FE

Question 7

how are impurities remove from the iron ore in a blast furnace

Answer 7

The main impurity in the mixture is silicon dioxide (sand)

Limestone and those thermal decomposition in calcium oxide

The calcium oxide reacts to silicon dioxide to from solid calcium silicate which can be removed from the furnace

this is a neutralisation reaction

Question 8

how does electrolysis work

Answer 8

When metallic compounds is melted or dissolved ions are free to move within the liquid or solution

passing a current through the molten liquid or solution means that their solution can be broken down into elements

during electrolysis the substance being broken down is the electrolyte

Question 9

what are the properties and uses of iron

Answer 9

malleable

an alloy, steel, can be forged from iron and carbon

steel is harder and stronger than iron and is less likely to rust

used to build cars and used in the construction industry

Question 10

what are the properties and uses of aluminium

Answer 10

low density

light weight for its size

resists corrosion due to very thin layer of oxides on the surface

used in aircraft, trains, overhead power cables, saucepans and cooking foil

Question 11

what are the properties and uses of copper

Answer 11

good conductor of electricity and heat

soft, easily bent and shaped (malleable)

resistant to corrosion (very unreactive)

used in electrical wiring, gas and water pipes, and plumbing in houses as copper does not react with water

Question 12

what are the properties and uses of titanium

Answer 12

low density

light weight for its size

resists corrosion

used in fighter aircraft, artificial hip joints and pipes in nuclear power

Question 13

what are the general properties of transition metals

Answer 13

high melting points

form coloured compounds

have the ability to form ions with different charges

most are malleable and ductile

good conductors of both heat and electricity due to their delocalised electrons

hard

less reactive than alkali metals ( group 1 metals )

Question 14

what is the test for metal ions

Answer 14

when sodium hydroxide (NaOH) is added:

copper (II) ions give a blue precipitate

iron (II) ions give a green precipitate

iron (III) ions give a brown precipitate

Question 15

what is an alloy

Answer 15

a substance made of a mixture of 2 or more elements, of which at least one is metal

they are made by mixing molten metals

the composition of alloys can be changed to produce alloys with desired properties

Question 16

explain what happens during the electrolysis of water

Answer 16

Electrolysis can be used to separate water into hydrogen gas and oxygen gas

positively charged hydrogen ions move to the negative electrode and gain electrons in a reduction reaction

negatively charged hydroxide ions move to the positive electrode and lose electrons to form water and oxygen in oxidation reaction

Question 17

what are the half equation in the electrolysis of water

Answer 17

at the cathode the equation is 2H+ + 2e- –> H2

at the anode the equation is
2OH- –> O2 + 2H+ + 4E-

Question 18

Explain what happens during the electrolysis of aqueous solutions

Answer 18

An ionic solution contains the irons that make up the ionic compound and the ions in water (OH- and H+)

at the cathode hydrogen is produced unless the positively charged ions in the ionic compound are from a metal less reactive than hydrogen than this metal will be produced it instead

at the anode, oxygen will be produced unless the ionic compound contains halide ions (Cl-, Br-, I-) in this case the halogen will be produced

Question 19

what are the electrode equations in the electrolysis of copper (II) chloride

Answer 19

At the cathode cup is less reactive than hydrogen copper ions are reduced to solid copper:
Cu2+ + 2e- –> Cu

At the aloe chloride ions are oxidised:

2Cl- –> Cl2 + 2e-

Question 20

What are the electrode equation in the electrolysis of sodium chloride

Answer 20

At the cathode hydrogen ions are reduced as sodium is more reactive than hydrogen
2H+ + 2e- —> H2

at the anode chloride ions are oxidised:
2Cl- –> Cl2 + 2e-

Question 21

what are the uses of electrolysis

Answer 21

Electroplating – covering the surface of one met up with another matter

Example: jewellery coated in silver to make it silver plated

manufacture of copper

Manufacture of sodium hydroxide, are you on gas and chlorine gas

Question 22

what factors must be considered when extracting metals

Answer 22

Site of extraction plants:
Good infrastructure, close to power station, near a city as a source for workers, away from built-up areas due to noise and pollution

The method used – reduction with carbon can be used where possible to lower energy and cost needed

Recycling – Using recycling plant to recycle and reuse material as opposed to extract new raw materials

Question 23

why is aluminium oxide dissolved in molten cryolite

Answer 23

Alumina (aluminium oxide) dissolves in molten cryolite at a
temperature much lower than its melting point, therefore
saving energy