doesnt contain sodium stearate and
wont react with calcium ions to form
scum
scale
insoluble solid
reduces efficiency
lather
hard- contains dissolved
compunds----magnesium and
calcium
Benefits of hard water
bone development
teeth development
reduce heart disease
reduces risk of lead poisioning
ans some intestinal cancers
increases overall lifespan
hard water can be either
temporary
can be
softened by
heating/boiling
permanent
remains hard
even when
heated/boiled
Softening Hard water
add washing soda - sodium carbonate
calcium+carbonate=calcium carbonate+sodium
ion exchange column contain resins
sodium or hydrogen ions in the resin
calcium and magnesium exchanged with the sodium/hydrogen in the resin
temp hard water contain hydrogencarbonate ions(HCO3-)
hydrogencarbonate ions when heated decompose
into carbonate ions which react with magnesium or
calcium ions found in the hard which leaves us with
either magnesium carbonate or calcium carbonate
limescale - as hard warer
evaporates/heated some carbon dioxide is
lost with the water and calcium carbonate
reforms....can be easily removed by
dissolving in a weak acid
drinkable water
filter beds remove smaller and smaller solids...if from river
it would be passes through sieve to remove large objects
activated carbon---- charcoal that is
broken up inro granules to increase
surface area an then treated to give
pieces a slight positive charge. some
contaminents stick to filter which should
be replaced regularly
ceramic filters with
microscopic particles of
silver - kill any
microorganisms that might
otherwise grow in the filter
Purify or enhance
distillation--evaporate sea water and allow re
condensation eleswhere leaving salt and
impurities behind
expensive
screens made of metal---remove debris like leaves or twigs that are in the reservoir
settlement tank - sand,soil settles out
aluminium sulfate- makes particles of dirt clump together and settle ( aka coagulation or flocculation)
filter bed - fine sand filters remaining particles (insoluble solid)
add chlorine - to kill bacteria / (added in some area) fluorine - hardens teeth
fluorine - reduce tooth decay and
added only in tiny amounts but
possible links with learning difficulties
and unethical (no choice if we can
have fluroine or not)
carbon - remove/reduce chlorine levels an possibly other
chemicals eg trace of pesticide
ion exchange resin removes calcium magnesium mainly