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