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Title: Agriculture and Industry OCR B F335
Description: These are detailed notes produced for the OCR B chemistry A2 salters course. These notes work through each specification point in detail using storyline, chemical ideas and the revision guide, answering each question and giving diagrams and explanations on how to carry out necessary calculations. The breadth of these notes makes them suitable for students at any grade in A2.
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Agriculture and Industry
Calculate oxidation states and recall and write full and half equations for the redox reactions involved in the
interconversion between compounds in the nitrogen cycle

Compound

Systematic name

N2
NO3NO2NH4+
NH3
N2O (colourless)
NO (colourless)
NO2 (brown)
N2O4 (colourless)

Nitrogen gas
Nitrate (V) ion
Nitrate (III) ion
Ammonium ion
Ammonia
Dinitrogen (I) oxide
Nitrogen (II) oxide
Nitrogen (IV) dioxide
Dinitrogen tetroxide

Oxidation state of
Nitrogen
0
+5
+3
-3
-3
+1
+2
+4
+4

To produce balanced equation for the inter-conversion of these compounds, first the
number of atoms is balanced, then the charges using the addition of H+, e- or H2O
...
The standard
equation for an equilibrium reaction (under standard conditions) is:
π‘Žπ΄ + 𝑏𝐡 β‡Œ 𝑐𝐢 + 𝑑𝐷
The equation for the equilibrium constant is thus:
[𝐢] 𝑐 Γ— [𝐷] 𝑑
= 𝐾𝑐
[𝐴] π‘Ž Γ— [𝐡] 𝑏
The products are put over the reactants, and the number of moles of each molecule is
written as its power
...
8]2
[1
...
63]3

The values:

= 6
...
As the
temperature increases the Kc value also increases
...
10) and the equilibrium concentration values of
CH3COOH (0
...
245) and H2O (0
...
However we do not know the value for
ethyl ethanoate – CH3COOC2H5
...
10 =

[𝐢𝐻3 𝐢𝑂𝑂𝐢2 𝐻2 ] Γ— 0
...
255 Γ— 0
...
10 Γ— 0
...
245 = [𝐢𝐻3 𝐢𝑂𝑂𝐢2 𝐻2 ] Γ— 0
...
10 Γ— 0
...
245
= [𝐢𝐻3 𝐢𝑂𝑂𝐢2 𝐻2 ] = 0
...
437
Describe and explain the way in which changes of temperature and pressure, and addition of catalysts affect
the magnitude of the equilibrium constant

We have already discussed that the only factor which can change Kc is temperature, as any
other changes will be counteracted by the system to resist the change
...

Using a catalyst does NOT increase the rate of reaction or the Kc
...

Calculate from given data the percentage yield and atom economy of an industrial process, and suggest the
effect of the process on the environment

π‘ƒπ‘’π‘Ÿπ‘π‘’π‘›π‘‘π‘Žπ‘”π‘’ 𝑦𝑖𝑒𝑙𝑑 =

π‘Žπ‘π‘‘π‘’π‘Žπ‘™ 𝑦𝑖𝑒𝑙𝑑
π‘‘β„Žπ‘’π‘œπ‘Ÿπ‘’π‘‘π‘–π‘π‘Žπ‘™ 𝑦𝑖𝑒𝑙𝑑

πΆπ‘¦π‘π‘™π‘œβ„Žπ‘’π‘₯π‘Žπ‘›π‘œπ‘›π‘’ + π‘β„Žπ‘œπ‘ π‘β„Žπ‘œπ‘›π‘–π‘’π‘š β†’ π‘šπ‘’π‘‘β„Žπ‘¦π‘™π‘’π‘›π‘’ π‘π‘¦π‘π‘™π‘œβ„Žπ‘’π‘₯π‘Žπ‘›π‘’ + π‘β„Žπ‘œπ‘ π‘β„Žπ‘œπ‘Ÿπ‘–π‘›π‘’ π‘œπ‘₯𝑖𝑑𝑒
98 + 276 β†’ 96 + 278
1000 tones of cyclohexanone produces 842 tonnes of methylenecyclohexane, what is the
percentage yield?
1:1 molar ratio of cyclohexanone and methylenecyclohexane
Therefore number of moles of the two will be the same:
1000
= 10
...
2 = 979
...
6

π΄π‘‘π‘œπ‘š π‘’π‘π‘œπ‘›π‘œπ‘šπ‘¦ =

π‘€π‘Ÿ π‘œπ‘“ 𝑒𝑠𝑒𝑓𝑒𝑙 π‘π‘Ÿπ‘œπ‘‘π‘’π‘π‘‘π‘ 
Γ— 100
π‘€π‘Ÿ π‘œπ‘“ π‘Ÿπ‘’π‘Žπ‘π‘‘π‘Žπ‘›π‘‘π‘ 

In the equation above, the useful product is methylenecyclohexane, therefore:

π΄π‘‘π‘œπ‘š π‘’π‘π‘œπ‘›π‘œπ‘šπ‘¦ =

96
96
=
Γ— 100 = 26%
98 + 276
374

Discuss given examples of industrial processes

ο‚·
ο‚·
ο‚·
ο‚·
ο‚·
ο‚·

Costs of raw materials e
...
transport/extraction/cost of the land/equipment
Energy costs – some processes much more energy intensive than others e
...

electrolysis
Costs associated with plant e
...
staff/renting infrastructure/lighting
Co-products – other useful products which can be sold produced alongside the main
product
By-products – products which are formed in unwanted reactions with little value
Green chemistry – recycling left over materials/waste, using efficient heating
systems to minimise heat use
Discuss the benefits and risks associated with given industrial processes

The development of a new chemical/compound can have important positive social impacts,
however there are also negative consequences
...

Much of the nitrogen comes from ammonia, developed by the Haber process:
2𝑁2 + 3𝐻2 β†’ 2𝑁𝐻3
As fertilisers are expensive, they are designed not to immediately leach out of the soil
...

Acidic soils inhibit plant growth – as H+ ions displace minerals such as Ca2+ in the soil
(particularly clay soil)
...

Aluminium oxide binds to H+ ions, further repelling vital cation nutrient ions from the soil
...

Soil pH can be controlled by adding alkali carbonates, such as chalk or lime
...


Pesticides can come in the form of insecticides (like pyrethroids) or herbicides
...

Total herbicides destroy all plant material; therefore they are applied before the crop is
sown to clear the field
...

Selective herbicides only kill specific target plants, and can therefore be applied whilst the
crop is growing
...
g
Title: Agriculture and Industry OCR B F335
Description: These are detailed notes produced for the OCR B chemistry A2 salters course. These notes work through each specification point in detail using storyline, chemical ideas and the revision guide, answering each question and giving diagrams and explanations on how to carry out necessary calculations. The breadth of these notes makes them suitable for students at any grade in A2.
Buy These NotesPreview