Chapter C15- Using Our Resources Flashcards
Why is nitrogen needed for in plants and in what form?
What other form does nitrogen have to be in for it to be useful to plants?
What is it called when something is fixed?
In what two ways can nitrogen be fixed naturally?
What does farming do to levels of nitrogen in soils and so what must happen?
What three chemicals are contained in fertilisers?
How can nitrogen be fixed industrially and what is the equation for this reaction?
What is the balanced symbol equation for this reaction?
What is the forward reaction and when is the rate of this reaction at zero?
What is the backward reaction in the Haber Process?
Needed for plant growth and in a soluble form
Needs to be in the form of ammonia or nitrates rather than the nitrogen gas in the air
Changed from the gas to a soluble compound
By lightning and some bacteria (legumes)
Depletes nitrogen in soils and so must be returned by fertilisers
Ammonium nitrates, sulphates and phosphates
By using the Haber Process (Nitrogen + Hydrogen === Ammonia)
N2 (g) + 3H2 (g) === 2NH3(g)
The forward reaction is exothermic but has zero rate at room temperature
The backward reaction is endothermic.
How is nitrogen obtained for the Haber Process?
How is hydrogen obtained?
What is equation for this?
What is the balanced symbol equation for this?
What high temperature is needed to optimise production and profits and why?
What high pressure is needed to optimise production and profits and why?
What else is needed to increase the rate of the Haber Process?
What happens to the unreacted nitrogen and hydrogen after the ammonia is removed by what two processes?
What are the two uses of ammonia and nitrates?
Nitrogen is extracted from the air
Hydrogen is obtained from methane and steam
Methane + Water—Carbon Monoxide + Hydrogen
CH4 + H2O — CO + 3H2
450 oC (high temperature) to increase rate but reduce yield
200 atmosphere (high pressure) to increase the rate and yield
Iron catalyst to increase the rate
The unreacted nitrogen and hydrogen is recycled back into the process after the ammonia is removed by cooling and condensation
Fertilisers and explosives.
Describe the reasons for use and disadvantages (and why) for the following optimisation factors:
High temperature
High Pressure
Catalyst (advantages as well)
Reason: Needed to increase the rate significantly
Disadvantages: More expensive (energy use and material requirements) and it reduces the equilibrium yield
Reason: Increases the rate and the equilibrium yield
Disadvantage: More expensive (energy and material requirements)
Reason: Necessary to increase rate
Advantages: Cheap and reused
Disadvantages: No effect on the yield.
How is nitrogen found in the air (concerning bonds)?
What is nitrogen in water?
What can most plants only absorb of nitrogen?
Why do plants need nitrogen to grow?
Found in the air with three covalent bonds
Nitrogen is insoluble in water
Most plants can only absorb a soluble form of nitrogen
As it’s one of the elements they need to make proteins
What three minerals do plants need and in what forms?
How can these be added to depleted soils?
What are these called?
What two things is ammonia from the Haber Process used to make?
How are phosphates obtained but what must it be treated with and why?
What two chemicals is potassium obtained from?
In what three ways can these then be extracted?
Plants need fixed nitrogen (ammonium salts or nitrates), phosphorous (phosphates) and potassium (potassium salts)
Can be added as fertilisers to depleted soils
NPK fertilisers
Ammonium salts or nitrates
Phosphate rock is mined but must be treated with acids to make soluble salts before it can be used as a fertiliser
Potassium chloride (KCL) and Potassium sulphate (K2SO4)
They can be mined; used directly (if soluble) or reacted to make other potassium salts.
What is the equation for the production of ammonium phosphate?
What is the balanced symbol equation?
What is the equation for the production of ammonium sulphate?
What is the balanced symbol equation?
What is the equation for the production of ammonium nitrate?
What is the balanced symbol equation?
Ammonia + Phosphoric Acid — Ammonium Phosphate
3NH3 + H3 PO4 — (NH4)3 PO4
Ammonia + Sulphuric Acid — Ammonium sulphate
2NH3 + H2SO4 — (NH4)2 SO4
Ammonia + Nitric Acid — Ammonium Nitrate
NH3 + HNO3 — NH4 NO3.
What is the equation for the reaction of phosphate rock and nitric acid?
What is the equation for the reaction of phosphate rock and sulphuric acid?
What is the equation for the reaction of phosphate rock and phosphoric acid?
Phosphate rock + Nitric acid — Phosphoric acid + Calcium Nitrate
Phosphate rock + Sulphuric acid — Calcium phosphate + Calcium sulphate (single superphosphate)
Phosphate rock + Phosphoric acid — Calcium phosphate (triple superphosphate).
Using what two methods is the reaction to produce NPK fertilisers in the lab carried out by?
What are the reactants in industry at?
What are the two advantages of this?
What has to happen to the mixture after the titration has been carried out and why?
Why isn’t crystallisation used in industry?
What two things are used for the reaction to produce NPK fertilisers in the lab?
What do these result in?
What is the heat released used to evaporate?
Why is this?
The reaction is carried out on a much smaller scale by titration and crystallisation
The reactants are at a much lower concentration than in industry
Less heat is produced by the reaction and it’s safer for a person to carry out
The mixture then needs to be crystallised to give pure ammonium nitrate crystals
Because it’s very slow
The reaction is carried out in giant vats and at high concentrations
A very exothermic reaction
Used to evaporate water from the mixture to make a very concentrated ammonium nitrate product
To make a very concentrated ammonium nitrate product.
Why do plants need the following minerals:
Nitrogen
Phosphorous
Potassium
To make amino acids and proteins
To make DNA and RNA
Needed for healthy growth.
What is corrosion caused by?
What is rusting?
Where does rust form on?
What is rust a form of and give it’s symbol equation?
What does rust have in its structure?
What is rust therefore called?
What is the equation for rust?
What two things must iron be in contact with in order to rust and where are these present?
When does corrosion only happen on the surface of a material?
Why does rust flake off and what does this cause?
What does this mean eventually happens to all the iron?
Chemical reactions between the metal and substances in the environment
The corrosion of iron
The surface of Iron and most steels
Iron (III) oxide, Fe2 O3
Rust has water loosely bonded in its structure
Hydrated iron (III) oxide
Iron + Oxygen + Water— Hydrated Iron (III) Oxide
Iron needs to be in contact with both oxygen and water, which are present in the air
When it’s exposed to the air
Rust is a soft crumbly solid that soon flakes off to leave more iron available to rust again
Eventually all the iron in an object corrodes away even if it wasn’t initially at the surface.
Why isn’t aluminium completely destroyed by corrosion?
How are the following methods of preventing rusting useful and achieved:
Painting/Coating with plastic
Electroplating
Oiling/Greasing
Describe the sacrificial method as a way of preventing rusting?
What then happens because of the new layer?
Describe the process of galvanisation?
What two advantages does this method of rusting provide?
Because the aluminium oxide that forms when aluminium corrodes, doesn’t flake away
Ideal for big and small structures alike. It can also be decorative too
This uses electrolysis to reduce metal ions onto an iron electrode. Can be used to coat the iron with a layer of a different metal that won’t corrode away
This has to be used when moving parts are involved, like on bike chains
This involves placing a more reactive metal such as zinc or magnesium with iron
Water and oxygen then react with the sacrificial method instead of with the iron
An object can be galvanised by spraying it with a coating of zinc
The zinc layer is firstly protective, but if it’s scratched, the zinc around the site of the scratch works as a sacrificial method.
What are two properties of pure metals?
What happens when forces are applied to the metal?
What are alloys and what do they produce?
What do the differently sized metal ions (or other atoms, such as carbon) cause in the alloy and why?
What does this mean?
What is bronze made by?
What are the two properties of bronze and give some examples of objects it is used to make?
What is brass made by?
What are three advantages/properties of brass?
What is brass used in the making of?
Relatively soft and easily shaped
Their regular layers of positive ions in their giant lattices can slide over each other
Mixtures of metals, producing more useful materials
Make it harder for the layers to slip- they are jammed in position
Alloys are much harder than the pure metals used to make them
Mixing copper with tin
It’s used to make statues and decorative items and to make ship’s propellers, because of its toughness and resistance to corrosion
Alloying copper with zinc
Brass is much harder than copper but it is workable, it can be hammered into sheets
Used in the making of musical instruments, such as trumpets, door fittings and taps.
What does aluminium have for a metal?
Why are aluminium alloys used to build aircraft?
What can other aluminium alloys be used as?
What is gold usually alloyed with when used to make jewellery?
What does pure gold do more easily than its alloy with copper?
What is pure gold also?
What is the purity of gold often expressed as and give an example?
What are steels?
How can the properties of steels be changed for their different uses?
What are the simplest steels and how are these made?
What are these steels?
A low density for a metal
Because they are lightweight but strong
Used as armour plating on tanks and other military vehicles
Usually alloyed with copper
Pure gold wears away more easily than its alloy with copper
Very soft
Often expressed in “carats”, where 24 carat gold is almost pure gold (99.9%)
Alloys of iron with carbon and/ore other elements
By carefully controlling the amounts of carbon and other elements
Carbon steels, which are made by removing most of the carbon from iron obtained from a blast furnace
These are the cheapest steels to make.
What are the properties, make up and uses for the following steels?
Low Carbon steels
High carbon steels
Stainless steels
How can we change the structure of a polymer?
What two things do the properties of a polymer depend on?
What are the two types of poly(ethene) made from?
What are the conditions required to make low density (LD) poly(ethene)?
What’s its property and what’s it used in?
What are the conditions required to make high density (HD) poly(ethane)?
What’s its property and what’s it used in?
Easily shaped and soft; (0.1-0.3% carbon); used in car bodies
Very strong, inflexible and brittle; (0.22-2.5% carbon); used in bridges
Corrosion resistant and very hard; made from chromium and sometimes nickel; used in cutlery
By changing the conditions
- The monomers used to make it
- The conditions chosen to carry out the reaction
Ethene monomers
Made from ethene at a moderate temperature under a high pressure and with a catalyst
It’s flexible and is used for bags and bottles
Made from ethene at a lower temperature and pressure, with a different catalyst
It’s more rigid and is used for water tanks and drainpipes.
What does the monomers that a polymer is made from determine?
What determines the properties of a polymer?
What are thermosoftening polymers?
What are two properties of these polymers?
What are thermosetting polymers?
What the four properties of these polymers?
What is cross linking?
The type of bonds that form between the polymer chains
These weak bonds between the different molecule chains
Polymers that contain individual polymer chains entwined together with weak forces between the chains
You can melt these plastics and remould them
Polymers that contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure
These polymers don’t soften when they’re are heated. They are strong, hard and rigid
Chains fixed together by strong covalent bonds.
