3.2 Water Flashcards

1
Q

What are the two types of water?

A

Hard and soft

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2
Q

Where is water hard?

A

Yorkshire, London and South East England

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3
Q

Where is water soft?

A

Lancashire, North Wales and the Lake District

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4
Q

What does Water hardness depend on?

A

The mineral ions dissolved into the water from the rocks

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5
Q

What ions make water hard?

A

Calcium and Magnesium

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6
Q

What are advantages of hard water?

A

Calcium strengthens bones and teeth

Calcium may also reduce the risk of heart disease

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7
Q

What are the two types of hard water?

A

Temporary

Permenant

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8
Q

What is temporary hard water?

A

High concentration of hydrogen carbonate ions

They decompose on heating

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9
Q

What is permanent hard water?

A

High concentration of sulfate ions

They don’t decompose when heated

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10
Q

What are two methods of removing water hardness if the water is temporary?

A

Boiling the water

Soap solution

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11
Q

What is created when hard water is heated?

A

Soft water and scale

Removing calcium, magnesium and hydrogen carbonate ions

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12
Q

What can scale do?

A

Reduce efficiency in kettles, boilers and pipes

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13
Q

What happens if you add soap solution to soft or hard water?

A

Soft - Lathers

Hard - Little Lather

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14
Q

What does hard water produce when reacted with soap solution?

A

Soft water and a precipitate called scum

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15
Q

What are two methods of removing water hardness if the water is permanent?

A

Adding sodium carbonate

Ion exchange column

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16
Q

What is produced when you add sodium carbonate to hard water?

A

Soft water
Precipitate of calcium carbonate
Precipitate of Magnesium carbonate

17
Q

What happens in an ion exchange column?

A

The resin beads have sodium and hydrogen in them

These ions exchange with the calcium and magnesium producing salt water

18
Q

Which method of removing water hardness is convenient and cost effective?

A

Ion exchange

19
Q

What are the 8 stages of water purification?

A
Filtering
Chlorine added 
Carbon filter
Filtering
Flocculation (solution added)
Filtering
Ion exchange 
Silver filter
20
Q

What do the three filters do in water purification?

A

Removes solids
Removes carbon
Removes precipitate of harmful ions

21
Q

Why is chlorine added in water purification?

A

To kill harmful microbes

But not too much as it is toxic

22
Q

Why is a carbon filter added in water purification?

A

To remove the chlorine

23
Q

Why is flocculation (solution added) in water purification?

A

Removes harmful ions (lead and mercury)

24
Q

Why is ion exchange used in water purification?

A

Removes hardness and adjust pH

25
Q

What is a silver filter used for in water purification?

A

Kills any lingering harmful organisms

26
Q

What are the advantages of adding fluoride to water?

A

Improves dental health - lowering tooth decay

It’s safe for humans

27
Q

What are the disadvantages of adding fluoride to water?

A

Too much can cause a painful bone disease

People should have the option to take extra fluoride or not

28
Q

How is pure water produced?

A

Distillation

29
Q

Why is pure water difficult to create?

A

It require a lot of energy for distillation

So it is a high cost as a result