6.3- EQUILIBRIUM REACTIONS IN INDUSTRY

Question 1

What is around 80% of ammonia used to make?

Answer 1

fertilisers like ammonium nitrate, ammonium sulfate + urea

Question 2

What is around 20% of ammonia used to make?

Answer 2

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

Question 3

Equation for making ammonia (reversible)?

Answer 3

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

Question 4

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

Answer 4

temperature + pressure

Question 5

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

Answer 5

low temp + high pressure

Question 6

By what process is almost all ammonia made by?

Answer 6

Haber process

Question 7

What are the raw materials for the Haber process?

Answer 7

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

Question 8

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

Answer 8

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

Question 9

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

Answer 9

1:3

Question 10

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

Answer 10

iron catalyst

Question 11

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

Answer 11

20 000kPa (around 200 atmospheres)

Question 12

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

Answer 12

670K

Question 13

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

Answer 13

to give maximum conversion

Question 14

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

Answer 14

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

Question 15

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

Answer 15

cooled so it becomes liquid + piped off

Question 16

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

Answer 16

fed back into reactor

Question 17

What size is the iron catalyst in the Haber process?

Answer 17

pea-sized lumps

Question 18

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

Answer 18

to increase SA

Question 19

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

Answer 19

about 5 yrs

Question 20

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

Answer 20

poisoned by impurities in gas stream + has to be replaces

Question 21

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

Answer 21

ammonia reacted with acid to make salt

Question 22

How is ammonia used to make ammonium nitrate?

Answer 22

ammonia reacts with nitric acid

Question 23

What is the next largest use of ammonia after fertilisers?

Answer 23

nylon

Question 24

What is ethanol in?

Answer 24

alcohol in alcoholic drinks

Question 25

Equation for ethanol production from fermentation?

Answer 25

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

Question 26

How is ethanol produced from fermentation?

Answer 26

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

Question 27

Examples of industrial uses of ethanol? (5)

Answer 27

``` cosmetics drugs detergents inks motor fuel ```

Question 28

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

Answer 28

ethene from crude oil

Question 29

How is ethanol obtained from ethene in crude oil?

Answer 29

obtained by fractional distillation + then cracking

Question 30

What process makes ethanol from ethene?

Answer 30

hydration- adding water

Question 31

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

Answer 31

reversible

Question 32

What catalyst is used to make ethanol from ethene?

Answer 32

catalyst of phosphoric acid absorbed on silica

Question 33

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

Answer 33

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

Question 34

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

Answer 34

all gaseous at temp used

Question 35

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

Answer 35

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

Question 36

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

Answer 36

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

Question 37

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

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

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

Answer 41

too much steam dilutes the catalyst

Question 42

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

Answer 42

about 570K + 6500KPa

Question 43

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

Answer 43

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

Question 44

What is methanol principally used as?

Answer 44

chemical feedstock

Question 45

What is methanol particularly used to manufacture?

Answer 45

methanal (formaldehyde)

Question 46

What is methanal used to make?

Answer 46

plastics i.e. Bakelite

Question 47

What plastics is methanol used in the manufacture of?

Answer 47

terylene + perspex

Question 48

Can methanol be used a motor fuel?

Answer 48

yes

Question 49

Equation for making methanol (reversible)?

Answer 49

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

Question 50

What is the starting gas mixture to make methanol called?

Answer 50

synthesis gas

Question 51

How is methanol made?

Answer 51

reacting methane or propane with steam

Question 52

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

Answer 52

low temp + high pressure

Question 53

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

Answer 53

temp- 500K | pressure- 10000kPa

Question 54

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

Answer 54

5-10% yield