2.6 Reversible reactions, industrial processes and important chemicals

Question 1

What is the Haber Process?

Answer 1

the production of ammonia

Question 2

What are the 5 stages in the Haber Process (industrial)?

Answer 2

1. Nitrogen and Hydrogen enter the chamber in a 1:3 ratio
2. Gases are compressed
3. Converter containing Fe catalyst causes hydrogen and nitrogen to react forming gaseous ammonia
4. Cooling tank condenses ammonia into a liquid
5. Unreacted gases are recycled.

Question 3

What is the optimum temperature of this process?

Answer 3

450*C

Question 4

What is the optimum pressure of this process?

Answer 4

200atm

Question 5

What is the catalyst in this process?

Answer 5

Fe/Iron

Question 6

Where does the nitrogen come from? The hydrogen?

Answer 6

Nitrogen- the air
Hydrogen- natural gases

Question 7

What type of reaction is used in making ammonia?

Answer 7

reversible

Question 8

What is the word equation in the Haber process?

Answer 8

Nitrogen + Hydrogen ⇌ Ammonia

Question 9

What is the symbol equation in the Haber process?

Answer 9

N(2) + 3H(2) ⇌ 2NH(3)

Question 10

What is meant by a closed system?

Answer 10

nothing can enter nor leave the system, eventually a dynamic equilibrium will be established

Question 11

Is nitrogen + hydrogen ⇌ ammonia exothermic or endo?

Answer 11

Exothermic

Question 12

is ammonia ⇌ nitrogen + hydrogen exo or endo?

Answer 12

Endothermic

Question 13

At low temperature is the yield high? Is the rate high?

Answer 13

High yield but slow rate of reaction

Question 14

At high temperature is the yield high? Is the rate high?

Answer 14

Low yield but fast rate of reactions

Question 15

When does pressure only affect reactions?

Answer 15

Both reactants and products are gases

Question 16

What side does an increase in pressure favour?

Answer 16

increase in pressure favours side of fewer moles

Question 17

What does high pressure do to ammonia’s yield?

Answer 17

The higher the pressure, the higher the yield

Question 18

Why is high pressure so expensive?

Answer 18

all the machinery and power needed for the reaction

Question 19

Does the direction go forward or backwards when : The pressure is increased?

Answer 19

Forward, the reaction makes more ammonia

Question 20

Does the direction go forward or backwards when : The ammonia is removed?

Answer 20

Forward, the reactions makes more ammonia

Question 21

Does the direction go forward or backwards when : The temperature is increased?

Answer 21

Backwards, the reaction is endothermic

Question 22

Does the direction go forward or backwards when : There are more molecules on the left?

Answer 22

Forward, removes extra molecules

Question 23

Does the direction go forward or backwards when : The reaction is cooled?

Answer 23

Forward, reaction makes more ammonia/exothermic

Question 24

Does the direction go forward or backwards when : The pressure is reduced?

Answer 24

Backwards, the pressure is higher on the left side

Question 25

Does the direction go forward or backwards when : The number of molecules on the left decreases?

Answer 25

Backwards, reaction favours less molecules/replaces molecules

Question 26

Why aren’t low temperatures used in the Haber process?

Answer 26

rate is too slow

Question 27

Why aren’t high temperatures used in the Haber process?

Answer 27

yield is too low

Question 28

Why isn’t low pressure used in the Haber process?

Answer 28

lower yield of ammonia

Question 29

Why isn’t high pressure used in the Haber process?

Answer 29

More pressure on ammonia so no balance/expensive

Question 30

What is the Contact process?

Answer 30

The production of sulphuric acid

Question 31

What are the raw materials used in the Contact process?

Answer 31

sulphur, air and water

Question 32

What happens in the first stage of the Contact process? What is the symbol equation for this?

Answer 32

Sulphur burned to make sulphur dioxide, (can be extracted from impurities in crude oil or natural gases)
S + O2 -> SO2

Question 33

What happens in the second stage? What is the symbol equations for this?

Answer 33

Sulphur dioxide turned in sulphur trioxide, catalyst vanadium oxide is used
2SO2 + O2 ⇌ 2SO3

Question 34

What happens in the third stage? What is the symbol equation for this?

Answer 34

Sulphur trioxide reacts with water to form sulphuric acid
SO3 + H2O -> H2SO4

Question 35

Why can’t sulphur trioxide be added directly to water?

Answer 35

It’s highly dangerous and clouds of sulphuric acid occur.

Question 36

What is sulphur trioxide added to instead and what is made?

Answer 36

Added to concentrated sulphuric acid called oleum
SO3 + H2SO4 → H2S2O7

Question 37

What is oleum then added to?

Answer 37

water to make sulphuric acid again
H2S2O7 + H2O → 2H2SO4

Question 38

Why can’t the temperature be low?

Answer 38

It’s an exothermic reaction so low temp is better but low rate

Question 39

What is the optimum temp in the contact process? pressure?

Answer 39

450*C
2atm

Question 40

Why is the pressure so low?

Answer 40

To reduce expense and explosion risks

Question 41

What are the uses of sulphuric acid?

Answer 41

detergents
paints
dyes
plastics
artificial fibres
dehydrating agent
fertilisers

Question 42

What happens to sugar and concentrated sulphuric acid?

Answer 42

Steam released, black liquid produced that turns into black solid

Question 43

What colour did the sugar go from?

Answer 43

white - orange - black

Question 44

Why has the sugar turned black?

Answer 44

Hydrogen and oxygen removed so only carbon remains

Question 45

What happens to hydrated copper sulphate and concentrated sulphuric acid? What’s all that remains?

Answer 45

copper sulphate goes from blue to white
only copper sulphate remains

Question 46

What is the reaction for making fertilisers?

Answer 46

NH3 + 2O2 -> HNO3 + H2O

Question 47

Apart from eutrophication, what other risks are there with nitrate fertilisers?

Answer 47

Nitrate fertiliser gets into our drinking water and causes possible health risks such as stomach cancer and ‘blue baby disease’.