Chemistry topic 10 Flashcards
(15 cards)
Where do natural resources come from?
Earth, sea and air.
They form without human imput.
Some can be replaced by synthetic products or improve done by man-made processes. E.g. rubber can be extracted from the south of the tree, but polymers have been made which replace rubber in uses such as tires.
Agriculture provides conditions were natural resources can be enhanced for our needs.
Which natural resources will run out?
Finite (nonrenewable) resources aren’t formed quick enough to be considered, replaceable such as fossil fuels, minerals, metals (found in ores). After extraction, many finite resources, undergo man-made processes, fractional distillation is used to produce usable products such as petrol from crude oil and metal ores are reduced to produce a pure metal.
What are the risks of extracting, finite resources?
Balancing social, economic and environmental effects of extracting them. For example, mining metal ores is good because it provides useful products and brings jobs and money in an area. However, it’s bad for the environment as well as people.
How is chemistry improving sustainability?
Natural resources are renewable search unsustainable to keep using them. Extracting resources can also be unsustainable due to the amount of energy used and waste produced.
Processing resources into useful materials can also be unsustainable as they use energy made from finite resources.
One way of reducing the use of these is the people to use less of them.
We can’t stop using them all together. The chemist can develop and adapt processes which lower amounts of the resources and reduce damage to the environment such as they have developed catalyst which reduce the amount of energy required for certain processes.
How are scientists making extraction for copper sustainable?
One way is through extraction from low-grade ores (not much copper in).
New ways which are being looked into include;
Bioleaching - bacteria are used to convert copper compounds in the or into soluble, copper compounds separating out the copper from the or in the process. The leachate, contains copper ions can be extracted by electrolysis or displacement.
Phytomining - plants in the soil which contain cover can be harvested, dried and burned. In a furnace. The ash contain soluble copper compounds from which copper can be extracted.
What are the benefits of the new copper extraction methods?
Traditional methods of copper mining, a pretty damaging to the environment. These new method of extraction have much smaller impact, but the disadvantage is that they are slow.
Why is recycling metals important?
Mining and extracting metals takes lots of energy, most of which comes from burning fossil fuels.
Recycling metals often uses much less energy than needed to mine and extract, conserves the finite amount of each metal, cuts down on waste.
Usually recycled by melting and casting them into shape.
Dependent on what the matter will be used for after recycling, the amount of separation required for recyclable metals can change.
E.g. way steel and iron can be kept together as added to a blast Furnace reduces the amount of iron ore required.
How can glass be recycled?
Glass bottles can be reused.
Other forms of glass can be recycled, separated by colour and chemical composition.
Glasses crushed the melted to be reshaped for use in glass products.
May also be used for different purposes, such as insulating glass wall for wall insulation.
What is a life-cycle assessment?
Shows the total environmental costs at every stage of a products life to assess the impact it would have on the environment.
Explain the four different steps of the life cycle assessments
Getting the raw materials (how they are extracted and processed)
Manufacture and packaging (pollution and waste, can be turned into useful chemicals).
Using the product (e.g. burning fuels can release greenhouse gases, fertilisers Leach ecosystems).
Product disposal - energy used to transport waste, and incineration, causes air pollution.
What are the problems with the life-cycle assessments?
Use of energy, some natural resources and certain types of waste can be easily quantified, but the effects of some pollutants is harder to give a numerical value.
Producing a life-cycle assessment is not an objective method as it can be biased.
They only show some of the impact the product will have on the environment.
What is potable water?
Water that’s been treated, or is naturally safe for humans to drink.
However, possible water can contain nuts of other dissolved substances, pH between 6.5 and 8.5.
Doesn’t contain solids, pathogens, or bacteria.
What are the different methods of producing potable water?
Filtration
Sterilisation:
To kill bacteria or microbes can be done by bubbling chlorine gas through it or using ozone or ultraviolet light.
Distillation (used to desalinate)
Where does waste water come from?
Sewage.
agricultural systems which produce slurries of nutrient run-off. (Has to be treated to remove harmful microbes and organic matter before being put back into freshwater sources.)
Industrial processes
What are the different stages of sewage treatment?
1) before being treated sewage is screened, removes large bits of material, such as twigs or grit.
2) it, then stands in a settlement tank and undergoes sedimentation, heavier, suspended, solids, sinc to bottom, to produce sludge, lighter effluent material flows on top.
3) the effluent in the settlement tank is removed and treated by biological aerobic digestion. Air pump through water, encourages aerobic bacteria to break down, organic matter in the water.
4) sludge is transferred to large, tanks and is broken down by bacteria in a process called anaerobic digestion. this breaks down, organic matter in sludge, releasing methane gas which can be used as an energy source, remaining waste used as fertiliser.
5) waste water containing toxins substances has chemicals added to it UV radiation, membranes or other additional treatment.
