Water Flashcards

1
Q

Why arent water sources clean

A

bacteria,dissolved substances and solids

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2
Q

Define potable water

A

water that is safe to drink

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3
Q

Define pure water

A

100% H20

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4
Q

What is surface water

A

water in lakes and such

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5
Q

What is ground water

A

water collected form rains underground

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6
Q

How is fresh water supplies turned into potable water

A

By passing water through filters beds and sterilising the water to kill microbes (chlroine,ozone and UV)

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7
Q

What do countries do if there is a lack of fresh water supply

A

Desalination

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8
Q

What is desalination

A

process of removing salt from saltwater

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9
Q

How is desalination done

A
  • Distillation ( Heated up so salt is left behind and steam is condensed)
  • Using membranes e.g. reverse osmosis
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10
Q

Define Reverse Osmosis

A

Water is put under high pressure and passed through a membrane which has tiny pores in it. The pores allow water molecules through but prevent most ions and molecules from passing through.

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11
Q

What are the disadvantages of reverse osmosis

A

It is expensive and not v efficient due to producing waste water

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12
Q

What are the 4 stages of waste water treatment

A

1) Screening and grit removal to remove large particles
2) Sedimentation allows tiny particles to settle out from still water
3) Sewage sludge digested anaerobically
4) The effluent is treated with aerobic bacteria to reduce the volume of solid waste

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13
Q

What are the findings of the required practical for analysis and purification of water

A
  • sea water contains the most molecules followed by mineral water hen rain and distilled water has none
  • Sea water is alkaline and distilled water is neutral. Mineral water/rain water are acidic
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14
Q

Define saturation

A

when a solution can no longer dissolve any more g/100cm3 of water at a given temp.

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15
Q

What is saturation dependent on

A

dependent on temperature and generally a higher temp. means more solute can be dissolved

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16
Q

What is solubility of a solute

A

the maximum amount that can dissolve in 100 grams of water at a given temp.

17
Q

What is solubility of a solute

A

the maximum amount that can dissolve in 100 grams of water at a given temp.

18
Q

Define soluble

A

If a substance is soluble it will dissolve in a given amount of liquid, called the ‘solvent’.

19
Q

What is a solute

A

the substance being dissolved by the solvent

20
Q

What does a solubility curve show

A

the relationship of solubility and temperature on a range of substances

21
Q

An example of calculating solubility to learn

A

Example: 12 g of potassium sulphate dissolve in 75 grams of water at 60 o C.
What is the solubility in water at that temperature?

75 g of water dissolves 12 g of potassium sulphate
So 1 g of water dissolves 12/75 g of potassium sulphate
So 100 g of water dissolves 12/75 x 100 = 16 g of potassium sulphate
The solubility of potassium sulphate in water at 60 o C is 16 grams.

22
Q

How do you test for water using Anhydrous copper (II) sulphate

A

It turns from white to blue in presence of water

23
Q

How do you test for water using anhydrous cobalt (II) chloride

A

It turns from blue to pink in presence of water