Chapter 10 - Using Resources Flashcards
What are the four key things humans use resources for?
- Warmth
- Shelter
- Food
- Transport
Where do resources come from?
Often from agriculture e.g. cotton from plants
Chemistry sometimes can provide a synthetic alternative that replace natural resources e.g. produce rubber from crude oil instead of getting it from the sap of a tree
What does sustainable mean?
We can meet our needs without preventing future generations from being able to meet theirs
What is pure water?
Water with no dissolved substances
What is potable water?
Water that is safe to drink (contains low levels of dissolved substances)
How to we produce potable water from fresh water?
- Find fresh water source e.g. river
- Pass through filter bed to remove leaves and suspended particles
- Sterilise to kill microbes using chlorine (or ozone or UV light)
What is the process called to get potable water from salty water?
Desalination
What are the two types of desalination?
- Distillation
- Reverse osmosis
What are the downsides to desalination?
Both methods require a lot of energy so are very expensive
How do you analyse if water is pure?
- Check pH by placing small amount of water onto universal indicator paper. If it turns green, pH = 7 and the water could be pure
- Test for solids (dissolved substances) - record weight of empty evaporating basin, then weigh with water. Evaporate water using a bunsen burner. Weigh basin again. If weight is higher than the weight of the empty basin then it is impure.
How do you purify water by distillation?
- Heat water until it evaporates and forms steam
- Steam travels along delivery tube and condenses in cold test tube
- This is distilled/pure water
What equipment is needed to purify water by distillation?
- Bunsen burner
- Tripod
- Gauze
- Conical flask
- Bung attached to delivery tube
- Test tube in ice bath (beaker filled with water and ice)
What is produced/what is the digested sludge used for?
- Biogas produced during digestion
- Digested sludge = fertiliser
Water is also used in industries e.g. to make paper and chemicals. What needs to be done before the waste water can go through general sewage treatment?
Harmful chemicals need to be removed
What is the easiest way to produce potable water?
Use ground water from aquifiers - usually safe once traeted with chlorine
Why are aquifiers sometimes not a safe source for potable water.
Can be polluted by things such as fertiliser. This means the water needs to be tested
Why is general sewage treatment only used for potable water when water is scarce?
There are so many steps so it is a long process
What is the easiest way to produce potable water?
Use ground water from aquifiers - usually safe once treated with chlorine
What is the usual method to extract metal?
Mining metal ores
Metals ores are running out. What are we going to have to use instead?
Low-grade ores
What is phytomining?
- Plants grown on land containing metal compound we want
- Plants absorb the compound
- The plants are harvested and burned, which produces an ash that contains a relatively high concentration of the metal compound
What is bioleaching?
- Bacteria is mixed with the low-grade ore
- The bacteria carry out chemical reactions and produce a solution called leachate
- The leachate contains the desired compound
After phytomining or bioleaching, how do we extract the metal from the metal compound?
Using displacement reactions or electrolysis
What is the aim of a life-cycle assessment?
It attempts to put a number on the environmental impact of a product
What stages make up a life-cycle assessment?
- Assess impact of extracting and processing the raw materials - how much energy is needed and are there any harmful waste products produced
- Assess the environmental impact if the product during its lifetime
- Disposal of products - energy required to dispose of harmful chemicals or transportation to landfill/recycling centre
What are the issues with life-cycle assessments?
- can’t always be certain how environmentally damaging something is so have to make estimations which aren’t always accurate
- can be biased to support advertisers’ best interests
Life-cycle assessment of a plastic bag
- made using chemicals from crude oil = non-renewable and extraction can be harmful to habitats
- needs to be chemically processed = lot of energy and waste products
- reusable and strong
- transportation to landfill
- non-biodegradable
Life-cycle assessment of a paper bag
- made using wood from trees = renewable but destructive to habitats
- production of paper requires a lot of water
- needs to be chemically processed = lot of energy and waste products
- one-time use as not strong
- transportation to recycling centre (heavier than plastic bags = more energy)
- biodegradable
Why is recycling important?
- Helps save limited resources and energy
- Reduces waste produced
- Reduces harm to environment
How is glass recycled?
- Products like glass bottles can easily be reused for the same use
- They can be crushed/melted to make different glass products
How is metal recycled?
- It is melted and then recast into different products
- Metals usually need to be separated before
