Global Reserves & Potable Water Flashcards
All 29 cards in this deck
What is sustainable development?
Development that meets the needs of current generations without compromising the ability of future generations to meet their own needs.
What is a finite resource?
A resource that is not being replaced (or is replaced much more slowly than it is used up).
e.g. crude oil, metal oresTrue or false? Timber from trees is a renewable resource.
True. Trees can be regrown at a similar rate to the rate they are used, so supplies are replaced.
Give two examples of natural products that are supplemented or replaced by agricultural or synthetic products.
Natural rubber replaced by synthetic rubber (from crude oil); cotton or wool supplemented by synthetic fibres such as polyester.
What does it mean to say one quantity is an order of magnitude larger than another?
It is about 10 times larger.
e.g. two orders of magnitude = about 100 times largerWhat is potable water?
Water that is safe to drink: it has sufficiently low levels of dissolved salts and microbes.
True or false? Potable water is pure water in the chemical sense.
False. Potable water still contains dissolved substances, so it is not chemically pure.
What are the steps used to produce potable water from fresh water in the UK?
e.g. water taken from a river- Choose an appropriate source of fresh water: a river, stream, lake or borehole
- Pass the water through filter beds to remove undissolved solids
- Sterilise the water (chlorine, ozone or UV light) to destroy harmful microbes
Name three sterilising agents used to make water potable.
Chlorine, ozone, or ultraviolet (UV) light.
What are the two methods of desalinating salty or sea water?
Distillation, or a membrane process such as reverse osmosis.
Both require large amounts of energy.Which process should a country with very little rainfall, a long coastline and plentiful energy supplies use to obtain most of its potable water?
Desalination of sea water, by distillation or reverse osmosis.
In the required practical on water samples, what three things are carried out on the samples?
Measuring the pH, finding the mass of dissolved solids, and purifying the water by distillation.
What is used to measure the pH of a water sample in the required practical?
Universal indicator (paper or solution) compared with a colour chart, or a pH meter/probe.
What are the steps to find the mass of dissolved solids in a water sample?
e.g. a sample of pond water- Weigh the empty evaporating basin
- Add a measured volume of the pond water and evaporate to dryness
- Reweigh the basin; the increase in mass is the mass of dissolved solids
What are the steps to purify a water sample by distillation in the lab?
e.g. a salty sea water sample- Heat the sample so the water boils and evaporates, leaving the dissolved solids behind
- Pass the vapour through a condenser, where it cools and condenses
- Collect the distillate — pure water
True or false? A sample of water that leaves no solid residue when evaporated to dryness contains no dissolved solids.
True. Dissolved solids would be left behind as a residue when the water evaporates.
Why must you never taste water samples in the required practical?
They may contain harmful microbes or dissolved chemicals.
What are the stages of sewage treatment?
e.g. sewage from homes- Screening and grit removal
- Sedimentation, producing solid sewage sludge and liquid effluent
- Anaerobic digestion of the sludge and aerobic biological treatment of the effluent
What two substances are produced by sedimentation in sewage treatment?
Solid sewage sludge (which settles) and liquid effluent (above it).
How is sewage sludge treated, and how is liquid effluent treated?
Sludge: anaerobic digestion. Effluent: aerobic biological treatment.
What must be removed from sewage and agricultural waste water, and what extra substances may industrial waste water contain?
Organic matter and harmful microbes; industrial waste water may also contain harmful chemicals.
Put ground water, waste water and salty water in order of how easy it is to obtain potable water from them.
Ground water is easiest, then waste water, and salty (sea) water is hardest.
True or false? Producing potable water from sea water uses less energy than treating waste water.
False. Desalination of sea water requires large amounts of energy, more than treating waste water.
Why are new ways of extracting copper, such as phytomining and bioleaching, being developed?
The Earth's resources of metal ores are limited and copper-rich ores are becoming scarce, so low-grade ores must be used.
What are the steps of extracting copper by phytomining?
e.g. land containing low-grade copper ore- Grow plants on the land so they absorb copper compounds
- Harvest and burn the plants to produce ash containing copper compounds
- Dissolve the ash in acid, then obtain copper by displacement with scrap iron or by electrolysis
What is bioleaching?
Using bacteria to produce leachate solutions that contain metal compounds (e.g. copper compounds).
What are the two ways of obtaining copper metal from a solution of copper compounds?
Displacement using scrap iron, or electrolysis of the solution.
Iron works because it is more reactive than copper.True or false? Phytomining and bioleaching avoid digging, moving and disposing of large amounts of rock.
True. That is their main advantage over traditional mining.
Give two reasons why phytomining is not yet widely used to extract copper.
It is very slow, and it needs large areas of land (also, high-grade ores are still available).