C3 WATER

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what makes water hard
Mg2+ and Ca2+ ions
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how does this happen
when rain infiltrates rock it picks up these ions
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3 examples of the rock
limestone, gypsum and chalk
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what is scum + disadvantage
when soap reacts with Ca2+ or Mg2+ it forms a layer of dirt on top of the liquid, its insoluble
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what is scale + 2 disadvantages
it is a carbonate that is left when water is boiled and leaves the ions behind, it blocks up pipes and acts as an insulator therefore reducing the efficiency of components
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2 pros and 2 cons to hard water
tastes nicer, reduces risk of heart disease and good for bones and teeth ; causes scum and scale
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what makes a water temporarily hard
hydrocarbonates
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what makes a water permanently hard
sulphate ions
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what method is used to remove temporary hardness
heating it up
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equation for it?
calcium hydrocarbonate=water+calcium carbonate+CO2
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what 2 methods can be used to remove temporary and permanent hardess
adding sodium carbonate in an ion exchange column
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what happens to washing powder made from sodium carbonate
the carbonate reacts with the Mg2+ and Ca2+ to form an insoluble precipitate
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what happens in an ion exchange column
the ions on the resin beads (Na+) are more reactive than the Ca2+ and Mg+ so they switch place and the ions are no longer in the water so it is not hard anymore
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why is silver present in an ion exchange column
to kill bacteria
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what does less soap mean
les Ca2+ snd Mg+ ions
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4 steps to clean water
large objects filtered out through screening,coagulant added to make small particles stick together,filtered through gravel beds,regulated amount of chlorine is added
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where does water come from and where does it go to
water stores such as reservoirs and is piped off to houses
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what is a coagulant
a substance that makes particles stick together
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why do people add carbon to their water after water process
remove the chlorine taste
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why do people add silver to their water after water process
kill any remaining bacteria
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why do people add water softeners to their water after water process
remove hard ions
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how do you get pure water
distil it
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why dont we distil all drinking water
too expensive
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why add fluoride ions to drinking water... 1+ 3-
reduces tooth decay, high doses can cause issues with bones and cancer, people want the choice, needs to be monitored to stop too much being added
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why add chlorine iones to drinking water... 1+ 1-
kills bacteria... can cause cancer due to the toxic by-products
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Other cards in this set

Card 2

Front

how does this happen

Back

when rain infiltrates rock it picks up these ions

Card 3

Front

3 examples of the rock

Back

Preview of the front of card 3

Card 4

Front

what is scum + disadvantage

Back

Preview of the front of card 4

Card 5

Front

what is scale + 2 disadvantages

Back

Preview of the front of card 5
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