c10: using resources

what is potable water?

water that is safe to drink

what is the difference between potable water and pure water?

potable water contains dissolved substances

state how to produce potable water.

1. Water passes through screens and then layers of sand and gravel to remove large debris, dirt, and suspended particles.

2. Chemicals might be added to clump tiny particles together for easier removal.

3. A sterilising agent (chlorine, ozone, or UV light) kills harmful bacteria, viruses, and other microorganisms.

4. Chemicals are added to adjust pH to a safe range

state the process of desalination.

This is energy-intensive but produces large quantities of freshwater:

• High pressure forces saltwater through semi-permeable membranes that block salt, allowing pure water to pass through.

• Saltwater is boiled; the steam (pure water) is collected and condensed, leaving salt behind

state how sewage is treated.

1. screening and grit removal

2. sedimentation to produce sewage sludge and effluent

3. anaerobic digestion of sewage sludge

4. aerobic biological treatment of effluent

state two ways of extracting copper from low grade ore.

1. phytomining

2. bioleaching

what is the process of phytomining?

it uses plants to absorb metal compounds. these plants are harvested and then burned to produce ash that contains metal compounds

what is the process of bioleaching?

uses bacteria to produce leachate solutions that contain metal compounds

define corrosion

the destruction of materials by chemical reactions with substances in the environment

state how corrosion can be prevented.

by applying a coating that acts as a barrier, like:

1. greasing

2. painting

3. electroplating

what is the difference between thermosoftening polymers and thermosetting polymers?

thermosoftening polymers melt when they are heated

thermosetting polymers do not melt when they are heated

what is the haber process used for?

to manufacture ammonia which can be used to produce nitrogen based fertilisers

what happens in the haber process?

1. nitrogen is extracted from the air and hydrogen obtained from natural gas close natural gas.

2. the purified gas is passed over a catalyst of iron at a high temperature (about 450°C) and a high pressure (about 200 atmosphere)

3. some of the hydrogen and nitrogen reacts to form ammonia

4. the reaction is reversible so some of the ammonia produce break down into nitrogen and hydrogen