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Chemistry GCSE > C6.1.1-6.1.7 > Flashcards

C6.1.1-6.1.7 Flashcards

(58 cards)

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1
Q

What are the essential elements plants need?

A

Nitrogen
Phosphorus
Potassium

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2
Q

Per element, what are the symptoms of deficiency?

A

Nitrogen - poor growth, yellow leaves
Phosphorus - poor root growth, discoloured leaves
Potassium - poor fruit growth, discoloured leaves

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3
Q

What are fertilisers and how can plant roots absorb them?

A
  • Substances that replace nutrients or minerals in plants

- Plant roots absorb them if they are water-soluble.

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4
Q

In what form do the fertilisers have to be for the plant to be able to absorb them?

A

Ions

e.g. NO3-, NH4+, PO4(3-), K+

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5
Q

What is the name given to fertilisers that are water soluble for plants.

A

NPK fertilisers.

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6
Q

What is the function of the Haber process?

A

To manufacture ammonia from nitrogen and hydrogen.

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7
Q

What is the equation for the haber process?

A

N2(g) + 3H2(g) (equilibrium symbol) 2NH3(g)

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8
Q

How are the reactants for the Haber process obtained and what are the raw materials required?

A

Raw materials: natural gas, air and steam
Nitrogen - fractional distillation of liquefied air (air is 78% nitrogen)
Hydrogen - react natural gas (mostly methane) with steam.

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9
Q

What is ammonia’s role within fertilisers?

A

Ammonia can be neutralised with acids to produce fertilisers.

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10
Q

What are the 4 main fertilisers?

A 
Ammonium nitrate (NH4NO3)
Ammonium sulfate (NH4)2(SO4)
Ammonium phosphate (NH4)3(PO4)
Potassium nitrate KNO3
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11
Q

Which raw materials can be used to produce ammonia?

A

Natural gas, air and water (Haber Process)

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12
Q

Potassium sulfate is a fertiliser, what reactants are needed to make it?

A

Potassium hydroxide and sulfuric acid.

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13
Q

Describe the process involved in the lab to create potassium sulfate.

A

1) Add dilute KOH(aq) and phenolphthalein into a conical flask
2) Using a burette add excess H2SO4 (aq)
3) Add acid until end point
4) Add activated charcoal to attract the indicator, then filter the solution to remove the charcoal and the indicator
5) Warm the filtrate to evaporate the water, don’t heat to dryness.

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14
Q

Describe the process involved when making ammonium sulfate.

A

1) Add NH3(aq) to conical flask with methyl orange
2) Add H2SO4 from burette until end point (yellow to red)
3) Add extra NH3(aq) to complete reaction.

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15
Q

What hazards come with the production of ammonium sulfate in the lab?

A
  • Ammonia gives an irritating sharp smell as ammonia gas is released (don’t breathe in)
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16
Q

What is the difference between a batch process and a continuous process?

A

A batch process is where substances are made on a small school ie in schools, whereas a continuous process is like that of large scale production.

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17
Q

What are the pros + cons of a batch process?

A
  • Low rate of production
  • Cheap equipment cost
  • Lots of people needed
  • Hard to automate the process
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18
Q

What are the pros + cons of a continuous process?

A
  • High production rate
  • Expensive equipment
  • Few people required
  • Work is continuous (no shutdowns)
  • Easy to automate
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19
Q

What are the 3 conditions required for the Haber process?

A
  • Pressure of 200 atmospheres (20MPa0
  • Temperature of 450 degrees C
  • An iron catalyst.
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20
Q

Why is the pressure 200 atmospheres in the Haber process?

A
  • There are 4 moles on the left and 1 mole on the right
  • At higher pressure there is a greater yield (favours the forward reaction)
  • Too expensive and hazardous at higher temperatures although yield of ammonia is higher.
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21
Q

Why is the temperature that value?

A
  • At higher temperatures the yield of ammonia is lower as the forward reaction is exothermic, reducing the temperature increases the yield but slows down the rate of reaction.
  • Temperature compromises rate of reaction with yield.
  • Iron catalysts work more efficiently at 400 degrees C
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22
Q

What is the % yield of ammonia in the Haber process and comment on why it’s so efficient.

A

It has a 97% yield

  • The unused nitrogen and hydrogen are recycled and used again so there are no waste products.
  • Ammonia condenses to a liquid.
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23
Q

What is the function of the iron catalyst?

A
  • Speeds up the rate of reaction reducing the need for higher temperatures
  • DOESN’T AFFECT YIELD.
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24
Q

Why is the ammonia liquefied?

Study These Flashcards
A

Allows it to be easily removed and for the unused reactants to be removed.

25
What is the purpose of the contact process?
To make sulfuric acid.
26
What 3 raw material are required for the contact process?
- Air (oxygen source) - Water - Sulfur
27
What happens in stage 1 of the the production of suluric acid?
- Sulfur (s) is burnt in air to produce sulfur dioxide. | S(s) + O2(g) > SO2(g)
28
Briefly, what happens in stage 2 (the Contact Process)?
The sulfur dioxide is reacted with oxygen to make sulfur trioxide. 2SO2(g) + O2(g) (equilibrium sign) 2SO3(g)
29
What are the conditions required for the Stage 2 of the contact process?
- Pressure of 200kPa (2 atmospheres) - Vanadium pentoxide catalyst (V2O5) - Temperature of 450 degrees C
30
What is the equilibrium yield of sulfur trioxide?
96%
31
What happens in stage 3 of the production of sulfuric acid?
Water is reacted with sulfur trioxide to produce sulfuric acid H2O(l) + SO3(g) > H2SO4(aq)
32
What factors determine the pressure chosen in Stage 2 for the Contact Process?
- 3 moles of gas on the left and 2 moles on the right, the equilibrium position is already on the right. - Although a high pressure would increase yield, the yield is already very high and it would be expensive to do so. - 2kPa is enough to push the gases through the converter.
33
What factors determine the temperature for the contact process in stage 2?
- The catalyst, vanadium pentoxide, only work above 380 degrees C. - Reducing the temperature increases the yield but if it is too low the reaction rate will be very slow so the temperature is compromised.
34
What are the hazards involved in stage 3 of the production of sulfuric acid?
- The reaction between sulfur trioxide and water in stage 3 is highly exothermic, produces a hazardous acidic mist.
35
What is done to avert the hazard in stage 3 of sulfuric acid production?
Process carried out in 2 stages 1) Sulfuric acid reacts with the sulfur trioxide to make oleum. H2SO4(l)+SO3(g) > H2S2O7(l) 2) Oleum is reacted with water to produce a larger concentrated volume of sulfuric acid. H2S2O7+H2O(l) > 2H2SO4(aq)
36
What process is used to produce alcohol using renewable raw materials?
- Fermentation | - Yeast catalyses conversion of glucose to make ethanol and carbon dioxide.
37
What conditions are required for the fermentation of glucose?
- Temperature around 35 degrees C otherwise the yeast will denature if too high and cool if too low. - Normal atmospheric pressure.
38
What process is used to produce ethanol using non renewable materials?
Ethene is obtained from crude oil, Ethene is then hydrated to produce ethanol. Ethene + Steam (equilibrium sign) ethanol.
39
What conditions are required for the production of ethanol using no renewable materials?
- 300 degrees C - 60 atmospheres pressure - Phosphoric acid catalyst
40
Compare the cost of raw materials and conditions needed for the 2 ways of making alcohol.
Raw material cost high for hydration but low for fermentation Conditions are moderate for temp and pressure for fermentation but high temp and pressure for hydration,
41
Compare the energy requirements and rate of reaction needed for the 2 ways of making alcohol.
Energy for fermentation is low but high for hydration. | Reaction rate slow for fermentation but high for hydration.
42
Compare the yield and purity needed for the 2 ways of making alcohol.
Yield is 15% for fermentation but 95% for hydration. Fermentation - needs filtering and frac. dist. Hydration - no by products very pure
43
State the reactivity series with hydrogen and carbon.
``` Potassium Sodium Calcium Magnesium Aluminium (CARBON) Zinc Iron Tin Led (HYDROGEN) Copper Silver Gold Platinum ```
44
What is an ore?
A rock or mineral with enough metal to make it economically worthwhile to extract metals from it.
45
What are examples of ores and what metal compounds do they have?
Malachite - copper carbonate Bauxite - aluminium oxide Haematite - iron(|||) oxide
46
Why are metals chemically extracted from their ores?
Because the ore does not contain the pure form of the desired metal.
47
How is the method for extraction chosen?
If the desired metal is above carbon in the reactivity series, electrolysis is used. If the desired metal is below carbon in the reactivity series, it can be extracted by reacting with carbon or carbon monoxide as electricity for electrolysis is expensive.
48
Explain the first stage of copper extraction.
- Copper (||) sulfide roasted in air. | copper (||) sulfide + oxygen > copper oxide (s) + sulfur dioxide (g)
49
Explain the second stage of copper extraction.
Copper oxide is heated with carbon, it's an example of a redox reaction as copper oxide loses oxygen and is reduced and carbon gains oxygen and is oxidised. copper oxide + carbon > carbon dioxide + copper.
50
What is the name given to the reaction container which extracts iron?
A blast furnace
51
Which 4 raw materials are used to make iron?
- Haematite (iron ||| oxide) - iron ore - Hot air - Limestone - purify iron - Coke - made of carbon - made by heating coal without air
52
In the blast furnace, what is the first reaction?
- Coke reacts with oxygen making carbon dioxide | C(s) + O2(g) > CO2(g)
53
In the blast furnace, what is the second reaction?
- More coke then reduces the carbon dioxide to carbon monoxide C(s) + CO2(g) > 2CO(g)
54
In the blast furnace, what is the third reaction?
- Carbon monoxide reduces iron (|||) oxide | 3CO(g) + Fe2O3(s) > 3CO2(g) + 2Fe(l)
55
What are the products of the blast furnace?
- Molten iron with sandy impurities | - Waste gases such as carbon dioxide
56
What is stage 1 of molten iron purification?
Using limestone (calcium carbonate) - decomposes at high temperatures to form calcium oxide. CaCO3(s) > CO2(g) + CaO(s)
57
What is stage 2 of molten iron purification?
- Calcium oxide then reacts with silica in the impurities making calcium silicate. CaO(s) + SiO2(g) > CaSiO3(l)
58
What does the molten calcium silicate do?
Called slag | - Floats on molten iron and the iron and slag are separately at the bottom of the furnace.

Chemistry GCSE (8 decks)

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