Chemistry ✿ using resources

finite (non-renewable) resource

natural resources that exist in limited quantities and cannot be replenished quickly (e.g. fossil fuels, ores)

renewable resource

natural resources that can be replenished naturally over time (e.g. wood)

state 2 examples of natural products that are supplemented or replaced by agricultural and synthetic products

• rubber from trees are now supplemented by synthetic rubber made by man-made polymers

• ethanol and biodiesel from crops are now replaced by fossil fuels

potable water

water that is safe for humans to drink but contains some dissolved substances

pure water

water that only has H₂O molecules

fresh water

water that has low levels of dissolved substances and is collected from the ground (rivers or lakes)

In the UK, potable (drinking) water is produced from different sources of fresh water.

Explain how potable water is produced from fresh water. [3]

• find a source of fresh water such as a river

• pass water through filter beds to remove undissolved solids

• sterilise using chlorine to remove harmful microbes

give examples of 3 sterilising agents

• chlorine

• ozone

• UV light

Desalination

the process of removing salt and impurities from seawater by distillation or reverse osmosis

Water obtained by distillation does not need to be sterilised and is safe to drink.

Suggest why

distilled water is pure

suggests 2 disadvantages of using desalination by reverse osmosis/ distillation

• requires a lot of energy

• costly

phytomining

the process of burning plants to produce ash which contains metal compounds

Bioleaching

the use of bacteria to produce leachate solutions that contain metal compounds and is then processed after using scrap iron or electrolysis

how are metal compounds processed to obtain the metal?

by displacement using scrap iron or electrolysis

What is the pH of pure water?

7

Explain why it is more difficult to produce drinking water from waste water than from water in lakes.

• Water goes through more processes

• as it has more organic matter and microbes

What are 2 ways to desalinate water?

• distillation

• reverse osmosis

Explain how to produce potable water from waste water.

• screening and grit removal

• sedimentation to produce sewage sludge and liquid effluent

• sewage sludge is treated with anaerobic respiration

• liquid effluent is treated with aerobic treatment

liquid effluent

liquid waste or sewage discharge

sewage sludge

solid waste of sewage water

leachate solutions

a liquid that has drained through a solid material

what is a disadvantage of phytomining and bioleaching?

produce small yields

Life cycle assessment

a process which assesses the environmental impact of products in each of their stages

In an LCA (Life cycle assessment), what are the 4 stages that a product is assessed in?

• extracting and processing raw materials

• manufacturing and packaging

• use during its lifetime

• disposal at the end of its life, including transport and distribution at each stage

LCAs can sometimes be unreliable.

Explain why

• it is hard to exactly measure how much water, energy or natural resources are used and how much waste is produced

• it is hard to give a value to how much pollution harms the environment

• tcausing some LCAs to not be 100% based on facts and can be subjective

how are glass bottles reused?

they are crushed and melted to be reformed into different glass products

what does the amount of separation required for recycling depend on?

• the material

• properties required

give 3 ways to reduce the impact of use of limited resources

• use less limited resources

• reducing materials and energy used to make limited products

• recycle and reuse