C3: Water

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  • Created by: Callum
  • Created on: 11-04-14 00:49
Which two things does water naturally contain?
Microorganisms and dissolved salts
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How is drinking water produced (3 steps)?
1. Water passed through a filter bed (to remove solid particles) 2. Chlorine gas added (kills microorganisms) 3. Fluoride is added (reduce tooth decay)
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How can the quality of tap water be improved?
Pass the water through a filter containing carbon, silver and ion exchange resins
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How do you get pure water?
Distillation. Boil the water to get steam, condense it by cooling to get pure water.
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Why is distillation an expensive process?
It uses a lot of energy
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What does soft water form with soap?
A lather
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Why does hard water contain calcium and magnesium compounds?
The compounds dissolve into natural water as it flows over rocks
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What will hard water form with soap?
Scum
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What does temporary hard water contain? How is it softened?
Hydrogen carbonate ions. It is softened by decomposing these ions to produce carbonate ions. These carbonate ions react with calcium/magnesium ions to form precipitates.
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Give an advantage of hard water.
The dissolved compounds in it are good for your health (E.g. Calcium --> strong bones/reduced risk of heart disease)
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Give a disadvantage of hard water.
More soap is needed to form a lather because the soap first has to react with magnesium/calcium ions. This increases cost.
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The insoluble calcium carbonate forms a layer...
of Limescale. This coats the heating element in kettles and irons and clogs up hot water pipes and boilers making them less efficient.
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What do you need to do to make hard water become soft?
Remove the dissolved calcium/magnesium ions
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What does adding sodium carbonate solution do to hard water and how?
It softens it as the carbonate ions react with valium/magnesium ions to form calcium carbonate/magnesium carbonate, which precipitate out the solution (they're insoluble)
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What will hydrogen or sodium ions do to hard water?
They will replace the calcium/magnesium ions making the water soft.
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Why do water softeners need to be topped up?
To replace the sodium ions that have been exchanged
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Other cards in this set

Card 2

Front

How is drinking water produced (3 steps)?

Back

1. Water passed through a filter bed (to remove solid particles) 2. Chlorine gas added (kills microorganisms) 3. Fluoride is added (reduce tooth decay)

Card 3

Front

How can the quality of tap water be improved?

Back

Preview of the front of card 3

Card 4

Front

How do you get pure water?

Back

Preview of the front of card 4

Card 5

Front

Why is distillation an expensive process?

Back

Preview of the front of card 5
View more cards

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