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C6- EQUILIBRIA > 6.3- EQUILIBRIUM REACTIONS IN INDUSTRY > Flashcards

6.3- EQUILIBRIUM REACTIONS IN INDUSTRY Flashcards

1
Q

What is around 80% of ammonia used to make?

A

fertilisers like ammonium nitrate, ammonium sulfate + urea

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2
Q

What is around 20% of ammonia used to make?

A

synthetic fibres (including nylon), dyes, explosives + plastics like polyurethane

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3
Q

Equation for making ammonia (reversible)?

A

N2(g) + 3H2(g) = 2NH3(g)

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4
Q

What does the percentage of ammonia obtained at equilibrium depend on?

A

temperature + pressure

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5
Q

What conditions would give close to 100% conversion to ammonia in N2(g) + 3H2(g) = 2NH3(g) reaction?

A

low temp + high pressure

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6
Q

By what process is almost all ammonia made by?

A

Haber process

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7
Q

What are the raw materials for the Haber process?

A

air (provides nitrogen), water + natural gas (methane, CH4)

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8
Q

Equation for how the hydrogen is provided in the Haber process?

A

CH4(g) + H20(g) -> CO2(g) + 3H2(g)

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9
Q

In what ratio is the nitrogen and hydrogen fed into the converter for the Haber process?

A

1:3

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10
Q

What catalyst does the nitrogen + hydrogen pass over in the Haber process?

A

iron catalyst

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11
Q

What pressure do most plants run at for the Haber process?

A

20 000kPa (around 200 atmospheres)

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12
Q

What temperature do most plants run at for the Haber process?

A

670K

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13
Q

Why is a lower pressure + higher temp used in the Haber process?

A

to give maximum conversion

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14
Q

Why does the nitrogen + hydrogen flow continuously over the catalyst in the Haber process?

A

so gases do not spend long enough in contact with catalyst to reach equilibrium- about 15% conversion to ammonia

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15
Q

What happens to the ammonia once it has cooled in the Haber process?

A

cooled so it becomes liquid + piped off

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16
Q

What happens to any nitrogen + hydrogen that’s not converted into ammonia in the Haber process?

A

fed back into reactor

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17
Q

What size is the iron catalyst in the Haber process?

A

pea-sized lumps

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18
Q

Why is the iron catalyst in the Haber process pea-sized lumps?

A

to increase SA

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19
Q

How long does the iron catalyst in the Haber process last?

A

about 5 yrs

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20
Q

What happens beyond 5 yrs to the iron catalyst in the Haber process?

A

poisoned by impurities in gas stream + has to be replaces

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21
Q

How is ammonia used to make ammonium sulfate and ammonium nitrate?

A

ammonia reacted with acid to make salt

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22
Q

How is ammonia used to make ammonium nitrate?

A

ammonia reacts with nitric acid

23
Q

What is the next largest use of ammonia after fertilisers?

24
Q

What is ethanol in?

A

alcohol in alcoholic drinks

25
Q

Equation for ethanol production from fermentation?

A

C6H1206(aq) -> 2C2H50H(aq) + 2CO2(g)

26
Q

How is ethanol produced from fermentation?

A

fermentation from sugars i.e. glucose using enzymes in yeast as catalyst

27
Q

Examples of industrial uses of ethanol? (5)

A 
cosmetics
drugs
detergents
inks
motor fuel
28
Q

At present what is the main source of ethanol for industrial use?

A

ethene from crude oil

29
Q

How is ethanol obtained from ethene in crude oil?

A

obtained by fractional distillation + then cracking

30
Q

What process makes ethanol from ethene?

A

hydration- adding water

31
Q

What sort of reaction is the production of ethanol from ethene?

A

reversible

32
Q

What catalyst is used to make ethanol from ethene?

A

catalyst of phosphoric acid absorbed on silica

33
Q

What is the equation for the production of ethanol from ethene?

A

H2C=CH2(g) + H20(g) = CH3CH2OH(g)

34
Q

What state are the products + reactants when making ethanol from ethene?

A

all gaseous at temp used

35
Q

For production of ethanol from ethene: what does a high pressure do?

A

high pressure will force equilibrium to move to right, to side with fewer molecules

36
Q

For production of ethanol from ethene: what does a low temp do?

A

low temp will force equilibrium to move to right to give out heat

37
Q

For production of ethanol from ethene: what will excess steam do?

A

excess steam will force equilibrium to right to reduce steam conc.

38
Q

For production of ethanol from ethene: what are the practical problems of high pressure? #1

A

tends to cause ethene to polymerise (to poly(ethene))

39
Q

For production of ethanol from ethene: what are the practical problems of high pressure? #2

A

high pressure increases cost of building plant + energy cost of running it

40
Q

For production of ethanol from ethene: what are the practical problems of low temp?

A

low temp will reduce ROR + so how quickly equilibrium reached, although this is partially compensated for by use of catalyst

41
Q

For production of ethanol from ethene: what are the practical problems of too much steam?

A

too much steam dilutes the catalyst

42
Q

In practice what conditions are used to make ethanol from ethene?

A

about 570K + 6500KPa

43
Q

What does the conditions of about 570K + 6500kPa to make ethanol from ethene give?

A

give conversion to ethanol of only about 5% but unreacted ethene separated from reaction mixture + recycled over catalyst again + again until its about 95% conversion obtained

44
Q

What is methanol principally used as?

A

chemical feedstock

45
Q

What is methanol particularly used to manufacture?

A

methanal (formaldehyde)

46
Q

What is methanal used to make?

A

plastics i.e. Bakelite

47
Q

What plastics is methanol used in the manufacture of?

A

terylene + perspex

48
Q

Can methanol be used a motor fuel?

49
Q

Equation for making methanol (reversible)?

A

CO(g) + 2H2(g) = CH3OH(g)

50
Q

What is the starting gas mixture to make methanol called?

A

synthesis gas

51
Q

How is methanol made?

A

reacting methane or propane with steam

52
Q

What conditions does Le Chateliers principle tell us that methanol synthesis will give the highest yield?

A

low temp + high pressure

53
Q

In practice what conditions are used for the synthesis of methanol?

A

temp- 500K

pressure- 10000kPa

54
Q

What is the percentage yield of methanol when the temp is 500K + pressure 10000kPa?

A

5-10% yield

C6- EQUILIBRIA (5 decks)

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