Using resources Flashcards
What do humans use the earth’s resources for?
Warmth, shelter food and transport.
What is meant by finite and infinite resources?
Finite- Limited
Infinite- Unlimited, replaced faster than used up.
What is chemistry responsible for in agriculture?
Improving industrial processes + creating sustainable methods of distributing products.
Give examples of how chemistry has replaced natural products for synthetic ones.
Rubber- extracted from tree sap (latex), now: rubber-like polymer.
Fertilizers- Enhance growth of plants.
What is…
renewable?
non-renewable?
Renewable- Infinite e.g. timber
Non-renewable- finite, used faster than replaced.
What is potable water?
Water that’s been processed + safe to drink.
What’s the difference between pure and potable water?
Pure- Solely H2O molecules
Potable- May contain small amounts of minerals.
What are the characteristics of potable water?
1- pH between 6.5 and 8.5
2- Limited amount of dissolved substances
3- Free of microbes
When is water considered fresh?
When its relatively free from dissolved substances
Where can water be collected from?
reservoirs, lakes and rivers (surface water) and aquifers (rocks storing water underground)= groundwater
How is potable water produced?
- Choosing source of freshwater
- Sedimentation: pass through filter beds
- Sterilizing: using chlorine, ozone, or ultraviolet light to remove microbes.
What is desalination?
Removing salt from salty water, could be done by distillation or reverse osmosis, require lots of energy so expensive.
Describe the method of RP8, analyzing water samples.
universal indicator to measure pH, weigh basin and add 25cm3 Water sample A, heat on tripod/gauze under Bunsen burner until water evaporates, weigh cooled basin + calc mass of solids, do same for sample B
Describe the method of RP8, purifying water samples.
Add water sample to conical flask+ set up apparatus for distillation, heat using Bunsen burner until boiling occurs, reduce the heat so that the water boils gently for some time, distilled water will collect in cooled test tube, analyze the water by determining its boiling point
What are the sources of waste water?
Domestic (passes into sewers), agricultural waste (farms/nutrient run-off) and industrial
What needs to be done to sewage and agricultural waste water during treatment?
Organic matter + microbes need to be removed, otherwise it could pose serious health risks.
What needs to be done to industrial water during treatment?
Removal of chemicals.
What are the steps of treating sewage water?
1- Screening/grit removal
2- Sedimentation: allow heavy solids sink to form sludge and lighter solids stay on surface (effluent)
3- Effluent (organic matter) broken down by aerobic digestion
4- Sludge broken down by anaerobic digestion to form methane gas + digested waste
What are the products of sludge broken down by anaerobic digestion and what are they used for?
Methane gas- energy
Digested waste- fertilisers
What happens after sewage water treatment if there are still microbes?
Chemicals can be added or ultraviolet radiation
Comment on the relative ease of
obtaining potable water from waste, ground and salt water.
Sewage treatment easier and cheaper than desalination, however treating fresh water is easiest.
Explain why alternative methods of extracting metals must exist?
Copper is becoming more scarce, so now low grade (non-economical) ores must be extracted cheaply.
Name the 2 ways of alternative methods of extracting metals.
Phytomining
Bioleaching
Explain Phytomining.
Plants grown where metals are known to be in the soil, they absorb metal through roots and become concentrated in roots and shoots. They are dried and burned and the ash must go through electrolysis or displacement to get the metal.
Explain bioleaching.
Some bacteria can break down ores into acidic solutions (leachate), acidic solution must go through electrolysis or displacement reaction. Produces toxic chemicals.
State the pros and cons of the alternative methods of extracting metals.
Pros: Avoid significant environmental damage, economical
Cons: Slow, require electrolysis/displacement reactions
What is the life cycle assessment used for?
Analysis of overall environmental impact that a product has throughout its lifetime.
What stages are assessed in LCAs?
Raw material extractions, Manufacturing, usage, disposal
What’s considered in the raw material stage of LCAs?
Using limited/unlimited resources, damaging habitats through deforestation/mining
What’s considered in the M+P stage of LCAs?
Land for factories, production of waste, transport
What’s considered in the usage stage of LCAs?
How many times used, how long its used, pollution produced
What’s considered in the disposal stage of LCAs?
recycled? burned? landfill?
How are LCAs carried out?
Some stages quantifiable, some not = biased. Some products don’t come with a complete LCA so paint good pic of company.
