Metals and Their Extractions

Question 1

Where are metals extracted from?

Answer 1

Ores

Question 2

What does the method of extraction depend on?

Answer 2

The stability of its compound in the ore, which in turn depends upon the reactivity of the metal

Question 3

What do very reactive metals form?

Answer 3

Form stable oxides and other compounds.
Electrolysis is commonly used to extract these metals and requires a lot of electric current (energy) to reduce them to extract the metal.

Question 4

What do less reactive metals form?

Answer 4

Form less stable oxides and other compounds. Reduction with carbon is often used to extract these metals and requires less energy to reduce them to extract the metal.

Question 5

What metals are extracted via electrolysis?

Answer 5

Metals more reactive than carbon

Question 6

What metals are extracted via reduction/displacement?

Answer 6

Metals less reactive than carbon

Question 7

What do more reactive metals have a tendency to do?

Answer 7

lose electrons and form positive ions

Question 8

What is the acronym for the reactivity series?

Answer 8

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Question 9

What does the speed of fizzing hydrogen bubbles tell us?

Answer 9

The speed at which hydrogen bubbles are produced tells us how reactive a metal is with acid. The quicker the fizzing, the more reactive the metal.

Question 10

Rules of displacement?

Answer 10

A more reactive metal will displace a less reactive metal from a compound.

Question 11

What is a thermite reaction?

Answer 11

Shows aluminium and iron oxide reacting violently in a thermit to produce metallic iron, using magnesium as a fuse. The aluminium changes to aluminium oxide. This is called a redox reaction as it combines reduction with oxidation

Question 12

What is reduction and oxidation?

Answer 12

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Oxidation is loss of electrons, gain of oxygen
Reduction is gain of electrons, loss of oxygen
example - iron from iron ore

Question 13

How does a blast furnace work?

Answer 13

1 - raw materials (iron ore, coke and limestone) added
2 - blasts of hot air are blown in at the bottom
3 - oxygen in air reacts with coke (carbon) to form carbon monoxide
4 - as the carbon monoxide rises up the furnace, it reacts with iron ore to form iron
5 - the molten iron runs to the bottom and is tapped off
6 - the molten iron is used to make steel or poured into moulds. the large chunks of iron that form are called pigs

Question 14

Chemical reactions in a blast furnace?

Answer 14

carbon + oxygen = carbon monoxide
2C + o2 = 2CO

iron oxide + carbon monoxide = iron + carbon dioxide
Fe203 +3CO = 2Fe + 3CO2

Question 15

How is aluminium extracted from electrolysis?

Answer 15

• Aluminium is heated to high temp to melt
• Positively charged aluminium ions move towards negatively charged cathode
• Aluminium atoms form that can be extracted as bulk metal

Question 16

What are the sustainability issues regarding extracting metals from their ores?

Answer 16

• Siting of the plants can have environmental effect and effect on local population
• Fuel and energy costs
• Greenhouse gas emissions
• ## Impact of recycling

Question 17

What properties do the transition metals have?

Answer 17

• malleable
• high melting points
• good conductors of electricity and heat
• form ions with different charges
• less chemically active than the alkali metals
• form coloured chemical compounds

Question 18

Where are the transition metals found on a periodic table?

Answer 18

In the centre.

Question 19

What colour precipitate forms when you add copper(II) to dilute sodium hydroxide solution?

Answer 19

Blue (jelly like)

Question 20

What colour precipitate forms when you add iron(II) to dilute sodium hydroxide solution?

Answer 20

Green (jelly like)

Question 21

What colour precipitate forms when you add iron(III) to dilute sodium hydroxide solution?

Answer 21

Rust-brown (jelly like)

Question 22

What is electrolysis?

Answer 22

Electrolysis is the process by which ionic substances are decomposed (broken down) into simpler substances when an electric current is passed through them.

Question 23

What happens during electrolysis?

Answer 23

Positively charged ions move to the negative electrode (cathode). They receive electrons and are reduced. (metals)

Negatively charged ions move to the positive electrode (anode). They lose electrons and are oxidised. The substance that is broken down is called the electrolyte.

Question 24

How would the electrolysis of zinc chloride work?

Answer 24

Zinc ions are changed into zinc atoms at the cathode, as they gain electrons.
Zn2+ + 2e- = Zn

Chloride ions change into chlorine gas at the anode, as they give up electrons.
2Cl- = Cl2 + 2e-
REMEBER GASSES GO ROUND IN PAIRS SO BALANCE EQUaTION

Question 25

What will happen at the cathode in electrolysis of ionic solutions?

Answer 25

Metal ions and hydrogen ions are positively charged. Whether you get the metal or hydrogen during electrolysis depends on the position of the metal in the reactivity series:

• the metal will be produced if it is less reactive than hydrogen
• hydrogen will be produced if the metal is more reactive than hydrogen

EXAMPLE***
the electrolysis of copper chloride solution produces copper at the negative electrode
the electrolysis of sodium chloride solution produces hydrogen.

Question 26

What will happen at the anode in electrolysis of ionic solutions?

Answer 26

If the negative ion from the ionic compound is simple (eg Cl- or Br-), then that element is produced. If the negative ion is a complex ion (eg NO3-, SO42-, CO32-), then oxygen is produced from the hydroxide ion present instead.

Question 27

What do halide solutions give off in electrolysis?

Answer 27

If a halide solution is very dilute (eg NaCl), then oxygen will be given off instead of the halogen. This is because the halide ions are outnumbered by the hydroxide ions from the water.

Question 28

What happens during the electrolysis of water?

Answer 28

Oxygen gas forms at anode
4OH = 2H20 + O2 + 4e-

Hydrogen gas forms at chathode
4H+ +4e- = 2H2

Both electrodes are usually made from platinum metal strips

2H2O = 2H +O2

Small number of ions produce -
H2O = 2H+ + OH-