Zusammenfassung der Ressource
C3 Part 1
- WATER
- Hard Water or Soft Water?
- Hard water is water that contains a lot
of dissolved compounds, usually
Calcium and Magnesium
- Water becomes hard when it flows
through chalk or limestone rock
- What happens
to rainwater?
- 1) Rain water reacts with Carbon Dioxide
in the air to form Carbonic Acid (slightly
acidic rainwater)
- 2) If the Slightly acidic water runs through a city with a high
amount of limestone, it reacts to form Calcium Hydrogen
Carbonate, which is dissolved in water to form hard water
- The more Ca2+ ions
present in the water,
the harder it is
- The harder the water, the more drops
of soap solution (Wanklyns) is needed
to form a lather
- Permanents hard water
remains hard when boiled
- Temporary hard water is
softened when boiled
- Making hard water soft
- To soften hard water you need to remove the
dissolved Calcium and Magnesium ions which
make the water hard
- Boiling
- By boiling the temporary hard
water you cause the Hydrogen
Carbonate ions to breakdown
into Hydrogen and Carbonate
ions. The carbonate ions that
are formed react with the
Calcium or Magnesium ions,
forming either Calcium
Carbonate or Magnesium
Carbonate which are
precipitates
- Adding Sodium Carbonate
- By adding Sodium Carbonate to the temporary hard water, we are in
effect adding Carbonate ions to the water. The carbonate ions react
with the Calcium ions (which are making the water hard in the first
place) to form Calcium Carbonate which is a precipitate
- Ion exchange columns
- Water for life
- Untreated water
- Microbes cause
diseases such as
Cholera and
Tetanus and can
cause health
problems
- Chemicals that make the
water smell, make the
water unpleasant to
drink
- Solid things (i.e
insects or toilet
paper) block pipes
and taps and may
carry microbes
- Salts, such as nitrates, cause
diseases such as Cholera and
Tetanus
- Treating water
- Microstainers
- Large rotating sieves which
remove solids including algae
- Sand Filters
- Football pitch sized
beds of sands, and 1m
deep, as water trickles
through solids and
harmful bacteria are
removed
- Chlorine is
added to kill
bacteria
- Ozone kills bacteria and
destroys pesticides
- Fluorides and filters
- Carbon Filter
- Removes chlorine
from water and
compounds with bad
tastes and smells
- Contains activated carbon. Has tiny
holes to increase surface area.
Unwanted substances stick to the
Carbon (ADSORPTION)
- Silver Filter
- Ions destroy bacteria
- Catalytic action of silver ions
with oxygen provides a sanitiser
which means we don't have to
use as much chlorine
- Ion Exchange resin
- Lead, Copper or
Cadmium ions are
removed
- They replace some
dissolved substances in
water to improve taste
and quality
- FOR
- 1 part/million
- Protect us from
tooth decay or
heart disease
- AGAINST
- Ethically wrong
- Cant set safe limits
of fluoride so people
may take more than
is safe
- Excess fluoride affects the brain
and has been associated with
Alzheimar's disease in old people