C15 - Using Our Resources 2️⃣✅ Flashcards
What is corrosion?
The destruction of materials by chemical reactions with substances in the environment
What is an example of corrosion?
Rusting
What 2 things are requried for iron to rust?
air and water
How can corrosion be prevented?
Applying a coating that acts as a barrier such as greasing, painting or eelectroplating.
What is galvanisation?
Applying a thin layer of zinc to metals such as steel or iron (Zinc more is more reactive so acts as a ‘sacrificial’ coating to prevent corrosion/ rusting)
What is an alloy?
An alloy is a mixture of two or more elements, at least one of which is a metal
What is a carat?
A method to measure the percentage of pure gold in an alloy of gold
What percentage of gold is 24?
100%
What percentage of gold is 18?
75%
What are the properties of the sructure of a pure metal?
- All atoms are the same size
- All atoms are in neat layers
- Malleable (due to the sliding layers of delocalsied electrons)
What are the properties of the structure of an alloy?
- 2 or more different sized atoms
- Layers/ patterns are disrupted
- Layers cant slider as easily therefore alloys are stronger and less mallelable than pure metals
What is an example of an alloy of iron?
Steel
What are the propeties of high carbon steel?
Strong but brittle
What are the properties of low carbon steel?
Softer and more easly shaped
What are the properties of steels containing nickel & chromium (stainless steel)?
Hard and resitant to corrosion
What is a thermostetting polymer?
Polymers that covalent bonds require alot of energy to break and therefore not melt when we heat them. This is because they have strong covalent bonds forming ‘cross links’ between their polymer chains
What is a thermosoftening polymer?
Polymers that have weak intomolecular forces that break easily when heated, causing the polymer to melt when they are heated. This is due to their tangled web of unstructred polymer chains and them being held together by weak intomolecular forces
What type of thermo-polymer is this structure?
Thermosetting
What type of thermo-polymer is this structure?
Thermosoftening
How is high density poly(ethene) made?
Low temperatures, low pressure & a catalyst
How is low density poly(ethene) made?
Moderate temperatures, high pressure & catalyst
What is the properties of high density of poly(ethene)?
More ridgid than LDPE but stronger
What is the properties of low density poly(ethene)?
More flexible than HDPE but weaker
How are ceramics made?
By shaping and firing a nonmetallic mateiral e.g. clay at a high temperature
What are the two main groups of ceramics?
Clay ceramics & glass
Give 3 examples of clay ceramics
Brick, china & porcelain
How are clay ceramics made?
Shaping wet clay while its soft and then heating it to a high temperature in a furnace, causing it to harden
What is the name of the type of glass that is most commonly used today?
Soda-lime glass
How is soda-lime glass made?
By melting a mixture of sand, sodium carbonate and limestone & then allowing the molten liqiud to cool down and solidify
How is borosilicate glass made?
By heating sand with boron trioxide
What is a difference in physical properties between borosilicate glass and soda-lime glass?
Boroscilicate glass has a much higher melting point than soda-lime glass
What is a phyiscal propety of clay ceramics that makes them ideal for bricks?
They have a high compressive strength
What does it mean if a material has a high compressive strength?
It can resist high levels of compressed forces before resisiting
What are some of the physical properties of glass that makes it ideal for windows?
- Transparency
- Strength
- Thermal insulation properties
What is a compostie/ compostie material?
A material that consists of two or mor materials with different properties that have been combined to produce a material with more desirable properties
What are the two components most compostie mateirals are made from?
The reinforcement & The matrix
What is the reinforcement?
Long solid fibres or fragments
What is the matrix?
Something that starts soft and hardens to bind all of the reinforcements together to form the composite
What is a common use for low density poly(ethene)
Carrier bags
What is a common use for high density poly(ethene)?
Drainpipes
What type of reaction is the forward reaction in the haber process?
Exothermic & therefore the backwards reaction is endothermic
What is the balanced symbol equation for the haber process?
What is the compromise solution for the haber process?
450°C & 200 atm with an iron catalyst
Describe the choice for 450°C as a compromise for temperature in the haber process
- As forward reaction is exothermic, lower temperatures would favour it & therefore give a high yield
- Although we want a higher temperature in order to increase the rate of reaction/ partciles colliding
- And higher temperatures cost much more money
- So 450 is a compromise between low for yield and high for rate
Describe the choice for 200 atm as a compromise for pressure in the haber process
- When pressurising the side of the equation with more molocules will be favoured (forward has 4mol : 2mol for backwards so forward favoured with higher pressure)
- A high pressure also means an increased rate of reaction as partciles are colliding more frequently
- Only thing limiting is costs as high pressure is expenisve
- So 200 atm is chosen as a compromise as its still high but is affordable to continuously maintain
Overall what could you say about the chosen pressure for the haber process?
Its low enough to not be expensive but high enough for a reasonable yeild and rate of reaction
Overall what could you say about the chosen temperature for the haber process?
Its low enough for a reasonable yeild but high enough for a high rate of reaction
Due to the compromise what is the rough %yeild of the haber process?
30% yeild
Where is nitrogen aquired for the haber process?
Just from teh atmosphere as our atmosphere is made up of almost 80% nitrogen
Where is hydrogen aquired for the haber process?
From hydrocarbons like methane
How does the haber process work?
- Reactans (nitrogen & hydrogen) are fed into reactor that has a temperature of 450°C, a pressure of 200atm and iron as a catalyst and therfore react to form ammonia (NH3)
- Due to the reversible attribute of the haber process some nitrogen & hydrogen is left over as some of the ammonia has reversed back into them
- In order to extract the ammonia for collection the gaseous ammonia, nitrogen & hydrogen is fed into a condenser where the ammonia is cooled down until it condenses into liquid ammonia to be collected
- The gaseous nitrogen & hydrogen does not condense as they both have lower boiling points so they stay as gasses and are circled back around to the reactor to undergo the reaction again
What are NPK fertilisers?
Formulations that contain nitrogen, phosphate & potassium that are water soluable salts that conatian all the necessary minerals plants require in order to grow
Why can phosphate rocks not be used in npk fertilisers?
Because the rocks are not water soluable so plants wouldnt be able to absorb it through their root hair cells
How is phosphate rock made useable in npk fertilisers?
It is reacted with acids to make it water soluable
What is produced when phosphate rocks are reacted with nitric acid?
- Phosphoric acid
- Calcium nitrate
What is produced when phosphate rocks are reacted with sulphuric acid?
- Calcium phosphate
- Calcium sulphate
- (This mixture is known as single superphosphate)
