C6 - Global Challenges

Which three elements are needed for plant growth?

N, P, K

In what form do fertilisers produce n + p + k?

water soluble ions

What do you react to make ammonium sulphate?

ammonia and sulphuric acid

What type of reaction is ammonia and sulphuric acid?

titration

What should you ensure you final product in a titration for fertilisers does not contain?

indicator, excess acid

What name can you give to small-scale fertilisation production?

batch

What name can you give to large scale fertilisation production?

continuous

Does continuous or batch scaler have a higher cost?

continuous

Does continuous or batch scaler have a higher production rate?

continuous

Does continuous or batch scaler have a higher shut down rate?

batch

Does continuous or batch scaler have a higher workforce?

batch

In which ways can ethanol be made?

fermentation of glucose, hydration of ethene

Give the balanced equation for the fermentation of glucose.

C₆H₁₂O₆₍ₐq₎ → 2O₂₍g₎ + 2C₂H₅OH₍ₐq₎

Where does glucose come from?

plant sugars

What is used to catalyse the fermentation of glucose?

yeast enzymes in cells

What temperature does the fermentation of glucose need to be?

35°C

What are the advantages of fermenting glucose to make ethanol?

low cost/modereate conditions/low energy

Gave the balanced symbol equation for the hydration of ethene.

C₂H₄ + H₂O ⇌ 2C₂H₅OH

Where does ethene come from?

crude oil

At what temperature is the hydration of ethene?

300C

At what pressure is the hydration of ethene?

60 atm

What is the catalyst used in the hydration of ethene?

phosphoric acid

What are the advantages of hydrating ethene to make ethanol?

high rate of reaction/high percentage yeild/high purity/no by-products

What is the percentage yield in hydrating ethene to make ethanol?

95%

What are the disadvantages of hydrating ethene to make ethanol?

high cost/ high conditions(therefore expensive)/ high energy requirement

What product is made in the Haber process?

ammonia(NH₃)

What is the symbol equation for the Haber Process?

N₂ (g) + 3H₂ (g)

What is the word equation for the Haber process?

nitrogen + hydrogen --> ammonia

What are the raw materials of the Haber process?

nitrogen, hydrogen

Where is nitrogen found?

atmosphere

Where is hydrogen obtained from?

reacting methane with steam

What is most of the ammonia used for?

fertilisers

What catalyst is used in the Haber process?

iron

What pressure is used in the Haber process?

200 atmospheres

What temperature is used in the Haber process?

450C

Why is a compromise used in the Haber process?

expensive to achieve high pressures (stronger equipment and more energy needed)

What is made in the Contact process?

sulphuric acid

What are the raw materials used in the Contact process?

sulphur, air, water

What is the word equation for stage 1 of the contact process?

sulphur + oxygen --> sulphur dioxide

What is the symbol equation for stage 1 of the contact process?

S(s) + O₂(g) --> SO₂(g)

What is the word equation for stage 2 of the contact process?

sulphur dioxide + oxygen --> sulphur trioxide

What is the symbol equation for stage 2 of the contact process?

2SO₂(g) + O₂(g) -> 2SO₃(g)

What is the word equation for stage 3 of the Haber process?

sulphur trioxide + water -> sulphuric acid

What is the symbol equation for stage 3 of the Haber process?

SO₃(g) + H₂O(l) -> H₂SO₄(aq)

Which stage of the contact process is in equilibrium?

stage 2

What pressure is used in the contact process?

2 atm

Why is the pressure of 2 atm used in the contact process?

the equilibrium position already lies far right

What temperature is used in the contact process?

450C

Why is the temperature of 450C used in the contact process?

the forward reaction is exothermic but a reasonable rate is needed

What catalyst is used in the contact process?

Vanadium(V) oxide

What is an ore?

a rock/mineral containing enough of a metal compound to make it economical to extract the metal

What is the ore for copper compounds?

malachite

What is the formula for copper compounds?

CuCO₃

What is the ore for aluminium compounds?

bauxite

What is the formula for aluminium compounds?

Al₂O₃

What is the ore for iron?

haematite

What is the formula for iron compounds?

Fe₂O₃

Whar is the name of the process used to extract aluminium?

electrolysis

Why is electrolysis used to extract aluminium?

it is more reactive than carbon

What do copper and iron react with to be extracted?

carbon

What do copper ores typically contain?

CuS (copper sulphate)

What happens in stage 1 in copper extraction?

copper(II) sulphate is roasted in air

What is the symbol equation for stage 1 in copper extraction?

2CuS(s) + 3O₂(g) -> 2CuO(s) + 2SO(g)

What happens in stage 2 of copper extraction?

the copper(II) oxide is heated with carbon

What is the symbol equation for stage two of copper extraction?

2CuO(s) + C(s) -> 2Cu(s) + CO₂(g)

What is reduced in copper extraction?

CuO / copper oxide

What is oxidised in copper extraction?

Cu / copper

What is the reducing agent in copper extraction?

C / carbon

How is iron extracted from its ore?

blast furnace, by reducing iron oxide with carbon

What is 'coke'?

carbon, coal

What happens in stage 1 of iron extraction?

coke burns in hot air

What is the symbol equation for stage 1 of iron extraction?

C(s) + O₂(g) -> CO₂(g)

What happens in stage 2 of iron extraction?

more coke reduces CO₂ to CO

What is the symbol equation for stage 2 of iron extraction?

CO₂(g) + C(s) -> 2CO(g)

What happens in stage 3 of iron extraction?

CO reduces the Fe₂O₃ at 1500C

What is the symbol equation for stage 3 of iron extraction?

3CO(g) + Fe₂O₃(s) -> 3CO₂(g) + 2Fe(l)

What is used to purify iron?

limestone (CaCO₃)

What are the two stages of purifying molten iron?

thermal decomposition, slag formation

What is the symbol equation for thermal decomposition?

CaCO₃(g) -> CaO(s) + CO₂(g)

What is the symbol equation for stage two of purifying molten iron?

CaO(s) + SiO₂(s) -> CaSiO₃(l)

What is aluminium oxide dissolved in before extraction?

molten cryolite

Why is aluminium oxide dissolved in cryolite before extraction?

reduces melting point temperaturre

What happens at the cathode when iron is extracted?

reduction

What is the half equation at the cathode in aluminium extraction?

Al3+ + 3e- -> Al

What is the half equation at the anode in aluminium extraction?

2O2- -> O₂ + 4e-

How can metals be extracted biologically?

bioleaching, phytoextraction

What type of ores is biological extraction typically used for?

low grade ores

How is thw metal extracted from the plants grown on ores?

absorbption of metal ions(sometimes complexing agent used). the plants are then harvested and burnt and the ash is used to extract the metal by electrolysis or reacting with carbon

What are the advantages of using bacteria to extract metals?

low energy (therefore cheaper)

What are the disadvantages of using bacteria to extract metals?

slow / can release toxic waste into water ways and soil

What is an alloy?

a mixture of two or more elements, at least one of which is a metal

What are the physical properties of steel?

strong

What is steel used for?

buildings, bridges, cars

What is duralumin?

alloy of aluminium and copper

What are the properties of duralumin?

lightweight

What is duralumin used for?

aircraft parts

What is solder?

alloy of tin and lead

What are the properties of solder?

low melting point

What is solder used for?

Joining electrical wires

What is brass?

alloy of copper and zinc.