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Poppy > Water > Flashcards

Water Flashcards

1
Q

What is hard water

A

Water in which it is difficult to form a lather with soap. It contains calcium and/or magnesium ions which react with soap to produce scum

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2
Q

What is scum

A

An insoluble solid formed when the dissolved compounds react with soap

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3
Q

What do soap less detergents do

A

Do not react with hard water to form scum

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4
Q

When water is in contact with rocks what happens

A

Some compounds dissolve

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5
Q

When is scale formed

A

When a type of hard water called temporary hard water is heated an insoluble solid called scale is produced

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6
Q

What caused blockages and reduces the efficiency of heating systems

A

Scale

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7
Q

What is the difference between scale and scum

A

Scum is formed when soap reacts with compounds in hard water. Scale is formed when temporary hard water is heated

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8
Q

What is calcium good for

A

Helping develop strong bones and teeth, reduces the risk of heart disease so hard water is better to drink than soft water

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9
Q

Why does soft water not produce scum

A

It may contain dissolved substances but I’d doesn’t contain dissolved salts which react with soaps to produce scum

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10
Q

How can hard water be made soft

A

Removing the dissolved calcium a den magnesium

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11
Q

Why is temporary water softened by heating

A

When it is heated the calcium and magnesium compounds form insoluble scale and this removes them from the water

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12
Q

Permanent hard water…..

A

Is not softened by boiling and does not produce scale when heated

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13
Q

What is meant by temporary hard water

A

Water that is softened by boiling and produced scale when heated

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14
Q

What kind of ions does temporary hard water have

A

Hydrocarbon ate ions

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15
Q

What do the hydrocarbon ate ions decompose to form

A

Carbonate ions, water, co2

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16
Q

What does the carbonate ions react with to form a precipitate which removes them from the water

A

The carbonate ions react with calcium and magnesium ions in the water to produce a precipitate of calcium carbonate and magnesium carbonate that are deposited as scale

17
Q

Describe the method used to soften either type of water

A

By precipitating out the ions that cause hardness, this is done by adding washing soda (sodium carbonate). The sodium reacts with calcium and magnesium in the water to form solid calcium carbonate and magnesium carbonate that cannot react with soap

18
Q

How does an ion exchange column work?

A

When the hard water passes through the resin calcium and magnesium ions become attached to the resin and sodium or hydrogen ions take their place in the water, these ions do not react with soap

19
Q

What is the temporary hard water decomposition equation

A

2HCO3 - (aq) ———-> Co3 2-(aq) + H2O(l) + CO2 (g)

20
Q

What should drinking water contain

A

No harmful substances and should have low levels of dissolved salts and microbes

21
Q

How is water often treated

A

By sedimentation and filtration to remove solids followed by disinfection to kill microbes (chlorine is often used for this)

22
Q

What are water filters used for

A

Improving the taste of water.

23
Q

How do water filters work

A

They often contain carbon and an ion exchange resin that removes some soluble substances and silver or another substance to prevent bacterial growth

24
Q

How is pure water obtained

A

Distillation,

25
Q

Why is distillation expensive

A

which requires a large amount of energy to boil the water and so it expensive

26
Q

Where must water be from t make it suitable to drink

A

An appropriate source

27
Q

What does the hardness of water depend on

A

Where you live

28
Q

What is a disadvantage of hard water

A

Can block and make heating systems less effective

29
Q

What is an advantage of hard wate f

A

Has health benefits

30
Q

If hard water is not suitable for a purpose what can be done

A

You can treate the water for an alternative supply

31
Q

What is good about softening hard water

A

Use less soap, does not produce scum, reduces the effects on heating systems

32
Q

DisAds of softening water

A

Reduces health benefits, expensive

33
Q

What is chlorine good for

A

Killing microbes

34
Q

Why is chlorine dangerous

A

It is poisonous and an produce toxic compounds

35
Q

Why is fluorine added to toothpaste and water

A

Prevent tooth decay

36
Q

Why are some people against adding Florida to water

A

People should Beatle to choose

37
Q

What is soft water

A

water containing no dissolved calcium and/or magnesium so it easily forms a lather with soap

Poppy (12 decks)

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