Extraction and use of metals Flashcards Preview

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Flashcards in Extraction and use of metals Deck (56):
1

the more reactive a metal is...

the harder it is to extract it from a compound

2

lots of common metals react with...to form...

oxygen...oxides

3

what is the reaction that involves the separation of a metal from the oxygen?

a reduction reaction

4

what is the reducing agent?

the substance that reduces the metal

5

what is the most common reducing agent?

carbon

6

copper oxide is reduced to copper:

2CuO + C = 2Cu + CO2

7

Methods of extraction are linked to the...

order of reactivity

8

only metals...than...can be reduced by...

less reactive...carbon...carbon

9

very reactive metals form...

very stable ores

10

metals that are more reactive than carbon need to be extracted using...

electrolysis

11

what is the melting point of aluminium?

2000 degrees celcius

12

what is aluminium dissolved in?

molten cryolite (a less common ore than aluminium)

13

What does the molten cryolite do?

it brings the temperature down to about 900 degrees celcius

14

what electrode are the aluminium ions attracted to?

the negative

15

what happens to the aluminium atoms once they gain electrons?

they sink to the bottom

16

why do the positive electrodes always need to be replaced?

they get worn down by reacting with oxygen

17

at the negative electrode:

Al3+ + 3e- --> Al

18

at the positive electrode:

202- --> O2 + 4e-

19

why is electrolysis expensive?

-it uses lots of electricity
-the need to heat the electrolyte
-the frequent replacement of electrodes

20

what are the raw materials used for extracting iron from iron ore?

-iron ore
-coke
-limestone

21

what is coke?

almost pure carbon

22

what is the purpose of limestone?

to take away impurities in the form of slag

23

step 1:

hot air is blasted into the furnace, making the coke burn much faster than normal
this raises the temperature to about 1500 degrees Celsius

24

Step 2:

the coke burns to produce carbon dioxide

25

step 2 equation:

C + O2 --> CO2

26

step 3:

the carbon dioxide then reacts with the unburnt coke to form carbon monoxide

27

step 3 equation:

CO2 + C --> 2CO

28

Step 4:

the carbon monoxide then reduces the iron ore to iron

29

step 4 equation:

3CO + Fe2O3 --> 3CO2 + 2Fe

30

step 5:

the iron is molten at this temperature but is also very dense, so it runs straight to the bottom of the furnace where it's tapped off

31

What is the main impurity from this process?

sand (silicon dioxide)

32

what removes the impurity?

the limestone

33

Step 1 of removing the impurity:

the limestone is decomposed by the heat into calcium oxide and carbon dioxide

34

Step 1 of removing the impurity: equation

CaCO3 --> CaO + CO2

35

Step 2 of removing the impurity:

the calcium oxide reacts with the sand to form calcium silicate, or slag, which is molten and can be tapped off

36

What is the cooled slag used for?

-road building
-fertiliser

37

what are the properties of aluminium and iron? (6)

-both dense and lustrous (shiny)
-high melting points
-high tensile strength
-malleable
-good conductors of electricity
-good conductors of heat energy

38

uses of iron:

-wrought iron (malleable)
-alloys

39

what is cast iron made of?

iron, carbon and silicon

40

what is steel made of?

iron, carbon and usually some other metals

41

what is the main problem with iron?

it corrodes easily

42

uses of aluminium:

-it doesnt corrode so is used for products that come into contact with water (eg drinks cans)
-aluminium is much less dense than iron so can be used for bicycle frames and aeroplanes

43

What is ammonia used for?

Fertilisers
Making nitric acid
Making nylon

44

Where does the nitrogen come from?

Air

45

Where does the hydrogen come from?

Natural gas

46

What temperature does the Haber process happen at?

450

47

What pressure does the haber process happen at?

200 atm

48

What is the catalyst used for the Haber process?

Iron

49

First step contact process

Majing sulfur dioxide

50

Second step contact process

Making sulfur trioxide

51

Third step contact process

Making liquid oleum

52

Fourth step contact process

Making concentrated sulfuric acid

53

Uses for sulfuric acid

Fertilisers
Detergents
Paints

54

Temperature contact process

450

55

Pressure contact process

2 atm

56

Catalyst contact process

Vanadium(v) oxide