Studied by 0 peopleHow was the Earth’s early atmosphere formed
Volcanic activity
Mainly CO2
Nitrogen, water vapour, traces of methane and ammonia
Volcanic activity released water vapour; condensed to form oceans; CO2 dissolved in oceans; carbonates produced sediments; carbon locked in sedimentary rocks; algae and plants evolved and absorbed CO2 by photosynthesis and released O2; carbon locked up in fossil fuels
Now: Amount of CO2 increased due to burning lots of fossil fuels, Difficult to predict effects.
What are the economies of developed countries based on
Energy obtained from fossil fuels so changes cost money to implement
What is carbon footprint
Total amount of CO2 and other greenhouse gases emitter over a product or event’s full life cycle. Reduce it by carbon capture.
How is sulfur dioxide produced and what does it do
When sulfur impurities burnt in fuels. Forms acid rain. Can be removed before burning. Change conditions where hydrocarbons are burnt
What are some examples of natural resources
Metal ores
Crude oil
Limestone
Why is the time left before fossil fuels run out only rough estimates
Uncertainties in calculations
What gases cause global dimming and respiratory problems and acid rain
carbon monoxide, sulfur dioxide, nitrogen oxides
What is potable water
water that is fit to drink
How to make potable water
Reservoir: As water enters water treatment. Metal bars catch large objects.
Settlement Tank: sand and soil settle out
Aluminium sulfate and lime added (small dirt particles clump together and sink to bottom). Sludge dumped in landfill site.
Passed through fine sand and gravel filter removing remaining mud particles
Chlorine added to kill bacteria. Ozone or UV light used
pH of water checked corrected to neutral
How do you purify salt water
Made pure by distillation. Expensive process. High energy costs in boiling.
Flash distillation: boiling under reduced pressure
Desalination: converting salty water to potable
Reverse osmosis: membranes used to separate dissolved salts from salty water. Uses energy to make high pressures needed
how to make potable water from sewage water treatment
Sewage sent to pumping station
It is screened and large solid objects are removed. Same done in settlement tank
Primary sedimentation - Large paddles rotation push solids (sludge) to centre of tank, through pipe to storage
Secondary sedimentation - Biological treatment. Aerobic digestion through useful bacteria by feeding on remaining organic matter and breaking it down.
Water is disinfected and sterilised by filtration, chlorine, ozone and UV light
Useful bacteria recycled back to secondary sedimentation tank
Water safe to drink
Sewage sludge treatment- dried and used as fertiliser or source of renewable energy by digesting anaerobically to make biomethane gas
How is copper metal extracted from ore
Sulfuric acid to make copper sulfate solution. Electrolysis
Smelting - ore heated to high temp. in furnace to make impure copper. Then used as electrode in electrolysis for pure copper. Expensive and polluting
How is copper extracted from phytomining
Use plants to extract copper from low grade ores
Grow plants on land containing copper ores
Plants burnt to produce ash
Ash dissolved in acid to produce copper compound solution
Electrolysis of solution
How does bioleaching work
Plant material mixed with specific type of bacteria which oxidise copper compounds within plant material to produce copper ions.
Copper ions are dissolved in solution to form copper sulfate solution and then electrolysis done
What is a Life cycle assessment and how is it done
Cost, energy, material inputs and outputs, and effect on environment
How to get raw materials and cost
How to make it
Can it be reused, recycled and cost
Actual disposal
What is corrosion
Caused by chemical reactions between metal and substances in environment. For iron, called ‘rusting’.
What is rusted iron called
hydrated iron (III) Oxide
What is needed for iron to rust
air and water
How can you prevent iron and steel from rusting
Paint
Oil/grease
Plastic
Less/more reactive metal
What is sacrificial protection
iron is attached to more reactive metal so it doesn’t rust. Iron is ‘galvanised’
What is the iron rusting experiment
Tube A - Calcium chloride (to absorb water), cotton wool, nail. Lid closed. → no rust
Tube B - Nail, boiled water, oil (so no air enters), lid closed. → no rust
Tube C - Water, nail, no lid. → rust
What are alloys
Mixture of metals. Harder than pure as regular layers in pure metal distorted by differently sized atoms.
What is bronze an alloy of
Copper and tin. Tough. Resist corrosion.
What is brass an alloy of
Copper and zinc. Musical instruments, taps. Harder
What is gold allowed with to make harder
Silver, copper, zinc
What is steel an alloy of
iron and specific amounts of non-metal carbon.
What is high carbon steel like
Hard and brittle. Make cutting tools.
What is low carbon steel like
Softer and more easily shaped
What is stainless steel an alloy of
Iron, carbon, nickel and chromium. Hard and resistant to corrosion
Why are aluminium alloys useful
Low density
What does the properties of a polymer depend on
monomers used
Conditions chosen to carry out reaction
How to form low density and high density polyethene
high pressures; catalyst with slightly raised pressure.
What are thermosoftening polymers like
soften or melt easily. Intermolecular forces relatively weak. Made up of individual polymer chains tangles together
What are thermosetting polymers like
Not soften. ‘Cross-linking’ so strong covalent bonds. Will eventually char if heated strongly.
Describe glass and its properties
Made from sand, limestone and sodium carbonate. Heated at high temp. to form molten glass.
Infinitively recyclable
Sustainable
withstand high temp.
Aesthetically pleasing
Brittle and fragile. Costly. High energy
Describe ceramics and its properties
-Heating mixtures of clay, powders and water and shaping. Heated in furnace. Covered in glazes (waterproof and shiny).
High energy to break.
Reusable
Good thermal insulator
long-lasting
brittle
Can’t be recycled
Describe polymers and its properties
From crude oil
Not biodegradable. Unsustainable
Reused and recycled
Cheap
Doesn’t break easily
Cracking and polymerisation → high energy
Describe composites
Made of 2 materials. One acts as binder for other, improving its properties → reinforcement
E.g. concrete, fibreglass, plywood
What is the equation for the haber process
Nitrogen(N2) + Hydrogen(3H2) →←(iron catalyst) Ammonia(2NH3)
Forward reaction exothermic
What are the conditions needed for the Haber process
200atm pressure
450C temp.
iron catalyst
What is the process of the Haber Process
Hydrogen and nitrogen gases pumped in
Mixture compressed to 200atm pressure and heated to 450C
Goes into reaction vessel with iron catalyst
Mixture of gases cooled in cooling chamber. Ammonia liquefies and gets separated
unreacted hydrogen and nitrogen returned to reaction vessel via compressor
How is nitrogen extracted from air
Fractional distillation of liquid air
How is hydrogen extracted
Reacting methane with steam
What are NPK fertilisers
Nitrogen, Phosphorus, Potassium
What is ammonia used for
Make nitric acid, which can be made into ammonium nitrate fertilisers.
Ammonia can be neutralised by sulfuric acid to make ammonium sulfate fertiliser or ammonium phosphate.
Can make potassium nitrate.
Making water potable practical
Experiment 1:
Universal indicator in water sample in test tube for pH
Weigh empty evaporating basin to 2d.p
Pour 10cm3 water in evaporating basin
Heat evaporating basin using bunsen burner till solid forms
Weigh cooled evaporating basin and calculate mass of solids. Record in table.
Increase in mass → has dissolved solids.
Experiment 2:
Place water sample in conical flask and set distillation apparatus
Heat water using bunsen burner till boils
Distilled water collect in cooled test tube. Pass through pipe with condenser around with cool water
Analyse distilled water by boiling point
What is carbon soot
Produced by burning fuels, especially coal. Cause global dimming and respiratory problems.
How to make ammonium sulfate in lab
Crystalisation of ammonia solution and sulfuric acid
Why is industrial process better than lab process
large scale, quicker, continuous process so economically better
Fertilisers are…
formulations with different required properties
What is the reaction when metal carbonate heated
decomposition
When saying why ores arent good, say…
conserves finite ores
Whenever saying why something is better, say…
more useful, used as fuels, are in greater demand
Do alkanes or alkenes produce more soot
alkenes due to incomplete combustion. Long-chained hydrocarbons produce more soot
Why are those conditions chosen in Haber process
Chosen is compromise to yield, safety and cost
What conditions do bacteria need in fermentation
anaerobic and warm
Why is methanoic acid stronger than ethanoic
Lower pH, more H+ ions, more frequent collisions, will reform less easily from ions
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