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GCSE AQA Chemistry > C15 - Haber process > Flashcards

C15 - Haber process Flashcards

1
Q

haber process

A

used to manufacture ammonia
- for nitrogen fertiliser

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2
Q

haber process materials

A

hydrogen
nitrogen

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3
Q

hydrogen from

A

natural gas

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4
Q

nitrogen from

A

air

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5
Q

Haber process steps

A
  • purified gases are passed over iron catalyst at high temp + pressure
  • react to form ammonia
    -ammonia is removed by cooling gases = liquifies
  • separated from unreacted gases
  • recycled into reaction mixture
  • recompressed/heated before returning to reaction vessel
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6
Q

reversible reaction - H2 + N2

A
  • some ammonia produced breaks down
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7
Q

nitrogen gas costs

A

-free from air
-costs to separate from other gases (fractional distillation)
- cooling process air must be pressurised - expensive pumps

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8
Q

hydrogen obtained by

A
  • react methane with steam at high temps
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9
Q

hydrogen costs

A

water = cheap
- heating is expensive
-methane = expensive

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10
Q

effect of pressure of haber process

A

-volume of reactants > products
- favours forward reaction

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11
Q

max ammonia yield

A
  • colder temps
    -max pressure
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12
Q

high pressure costs

A

expensive vessels

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13
Q

pressure in haber process

A

uses 200 atmospheres
- reduces cost but reasonable yield

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14
Q

effect of temp on haber process

A

forward reaction = exothermic
- lower temps favours forward

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15
Q

temp used in haber process

A

450 .c

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16
Q

too cold temps con in haber process

A

rate of reaction is slowed = less frequent collisions of gas
- must be quick = economical
- reduces effect of iron catalyst

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17
Q

iron catalyst

A
  • speeds up both reaction
  • doesn’t affect yield
  • speeds up rate of production to be economical
18
Q

ammonia purpose

A

to make nitric acid

19
Q

nitric acid purpose

A

reacts with more ammonia
-makes ammonium nitrate fertiliser

20
Q

ammoinia is an acid or alkali

A

alkali

21
Q

neutralisation of ammonia - sulfuric acid

A

ammonium sulfate fertiliser

22
Q

neutralisation of ammonia - phosphoric acid

A

-ammonium phosphate fertiliser

23
Q

acids used to neutralise ammonia

A

sulfuric
phosphoric

24
Q

NPK fertilisers

A

contain formulation of compounds to provide all 3 elements
- to improve agriculture
-nitrogen, phosphorus, potassium

25
Q

source of phosphorus

A

phosphorus rock -mined

26
Q

source of nitrogen

A

haber process

27
Q

why can’t phosphorus rock be used directly on soil

A

it is insoluble

28
Q

phosphate rock is treated with

A
  • nitric acid
  • sulfuric acid
  • phosphoric acid
29
Q

phosphate rock and nitric acid

A

-phosphoric acid + calcium nitrate
- then phosphoric acid is neutralised with ammonia = ammonium phosphate

30
Q

phosphate rock and sulfuric acid

A

single superphosphate (calcium phosphate)
and calcium sulfate

31
Q

superphosphate

A

calcium phosphate

32
Q

phosphate rock and phosphoric acid

A

calcium phosphate
triple superphosphate

33
Q

potassium

A

-potassium salts are mined
- eg potassium chloride or sulfate

34
Q

potassium prop

A

soluble
-just separated from impurities the used

35
Q

Temp - Industrial vs Lab Haber Process

A

I - 450.c
L - room temp and bunsen burner

36
Q

equipment and process - Industrial vs Lab Haber Process

A

I - expensive chemical plant machinery + continuous process
L - cheap + batch process

37
Q

Industrial vs Lab Haber Process - starting materials

A

I - raw materials
L - cheap supplier bought

38
Q

Industrial vs Lab Haber Process - scale/yield

A

I - large and quickly
L - small and slowly

39
Q

Industrial vs Lab Haber Process - running costs

A

I - low labour costs = machines
L - labour intensive and high running costs

40
Q

Industrial vs Lab Haber Process - reactant concentration

A

I - high concentrations + very exothermic
L - less so less heat given off

41
Q

Industrial vs Lab Haber Process - separation of product

A

I - heat produced evaporates water
- from reaction mixture
- makes concentrated ammonium nitrate
L - crystallisation = slow

GCSE AQA Chemistry (36 decks)

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