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Chemistry > Separating Mixtures And Water Treatment > Flashcards

Separating Mixtures And Water Treatment Flashcards

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1
Q

What does soluble mean?

A

A substance that will dissolves in fluid to form a solution

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2
Q

What does insoluble mean?

A

A substance that will not dissolve in a solvent (even after mixing)

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3
Q

What is a solute?

A

A substance that has dissolved in a solution (usually a solid)

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4
Q

What is a solvent?

A

A substance that dissolves a solute (usually liquid)

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5
Q

What is filtration?

A

Filtration separates an insoluble solid from a liquid

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6
Q

How does filtration work?

A

The liquid filtrate passes through the filter paper and the undissolved solid residue stays on the paper

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7
Q

What is decantation?

A

Decantation is another way of separating a liquid from an undissolved solid

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8
Q

How does decantation work?

A

A liquid is poured very slowly leaving the solid behind

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9
Q

What is evaporation?

A

Evaporation is used to separate a soluble solid from a solution

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10
Q

How does evaporation work?

A

The solution is heated as the solvent evaporates leaving the solid solute behind

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11
Q

What is crystallisation?

A

Crystallisation is another way is separating a soluble solid from a solution

  • it is often used when making crystals from a solution where the solvent is water
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12
Q

How does crystallisation work?

A

By heating the mixture then putting the solution in a warm place to slowly let the solvent evaporate leaving saturated crystals (from the solute) to form

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13
Q

Describe the crystals produced from crystallisation

A

-hydrated
-containing water in their structure
-if strongly heated the water would evaporate away leaving anhydrous power (a substance is anhydrous if it contains no water)

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14
Q

Describe copper sulfate:

A

-blue
-copper gives it its crystal structure

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15
Q

What is distillation?

A

Separating a solvent from a solution

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16
Q

What is a condenser?

A

An apparatus used to condense gas (turning them into liquid) by cooling them down

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17
Q

At what temperature does water distil off?

A

100 degrees Celsius

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18
Q

What do anti-bumping granules do ?

A

Prevent the formation of large gas bubbles that cause violent boiling

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19
Q

Apart from a condenser , what other piece of equipment can you use to apply distillation?

A

A delivery tube
(With ice cold water in a beaker)

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20
Q

What is pure water?

A

-Water without impurities
-Water that is 100% water and contains nothing else

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21
Q

What is a test to prove that a solution is pure water?

A

-it will boil at 100 degrees Celsius
-it will freeze at 0 degrees

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22
Q

What is are miscible liquids?

A

Two liquids that mix
(Eg alcohol and water)

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23
Q

How are miscible liquids separated?

A

Using FRACTIONAL DISTILLATION

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24
Q

How does fractional distillation work?

A

It uses a FRACTIONATING COLUMN allowing the separation of liquids that have boiling points that are different but are still quite close together

-The substance with the HIGHER boiling point condenses falling into the flask
-The substance with the LOWER boiling point emerges from the top

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25
Q

What are immiscible liquids?

A

Liquids that do not mix and form separate layers

26
Q

Examples of miscible liquids:

A

-ethanol(alcohol) and water
-petrol and diesel from crude oil

27
Q

Example of immiscible liquid:

A

Oil and water

28
Q

How are immiscible liquids separated?

A

Using a SEPARATING FUNNEL

-The liquid with a lower density stays at the top (eg oil)
-The liquid with a higher density stays at the bottom (eg water)

29
Q

Example of decanting and filtration:

A

Sand and water

30
Q

Example of evaporation:

A

Salt from salt solution

31
Q

Example of distillation:

A

-Water from salt solution
-alcohol from sugar dissolved in alcohol

32
Q

What is chromatography?

A

A method for separating several solids that are all soluble in the same solvent

33
Q

What can be separated using chromatography?

A
  • Dyes
  • Inks
34
Q

How does chromatography work?

A

-Dyes are placed at the BOTTOM of the chromatography paper
- This is then placed in a SOLVENT (eg water)
-As the water is drawn up the paper it moves different dyes at DIFFERENT RATES depending on their SOLUBILITY in water

35
Q

How do you know which dyes are more soluble?

A
  • dyes which are MORE soluble in water move more QUICKLY up the paper
  • dyes which are LESS soluble in water move SLOWLY up the paper
36
Q

What is the solvent and paper referred as?

A

Paper - stationary phase
solvent - mobile phase

37
Q

How do you work out the Rf value?

A

Rf = distance moved by pigment (measure centre of the spot)
—————————————
distance from pigment to solvent front

RF VALUES ARE USED TO IDENTIFY SUBSTANCES
-!THEY MUST BE LESS THAN 1 AND WRITTEN AS A DECIMAL!

38
Q

Why is the 1cm line drawn in pencil?

A

-Because graphite is insoluble
-because the ink from pen would separate from the paper and mess up the experiment

39
Q

Why are the spots labelled at the start?

A

Because they become unrecognisable after they separate

40
Q

Why MUST the water level be below the spots?

A

So that the ink doesn’t dissolve into the water

41
Q

What does the chromatogram tell you about the pens?

A

Most inks are made up of TWO OR MORE colours

42
Q

What is water suitable for drinking called?

A

Potable

43
Q

What is water treatment?

A

The process of making water safe to drink

44
Q

What does water treatment do?

A

-removes insoluble/dissolved solids from the water
-kills harmful bacteria

45
Q

What are the 3 main processes used to mark water clean enough to drink?

A

-sedimentation
-filtration
-sterilisation

46
Q

How does sedimentation work?

A

-Water is put in a tank where the water is very STILL
-PARTICLES of UNDISSOLVED SOLID sink to the bottom of the tank where they SETTLE
-WATER is removed from HIGHER up the tank which now contains less solid

47
Q

What are coagulants?

A

Chemicals that are sometimes added to help particles of solid to stick together to make larger lumps of sediment

48
Q

How does filtration work?

A

-Water is passed through a series of SAND FILTERS
-The sand filters REMOVE PARTICLES of INSOLUBLE/DISSOLVED SOLID

49
Q

How does sterilisation work?

A

Chlorine is added to the water supply to kill bacteria/microbes
(ANOTHER GAS CALLED OZONE CAN ALSO BE USED TO STERILISE WATER INSTEAD OF CHLORINE)

50
Q

What is ground water?

A

Water in underground streams and rocks

51
Q

What is fresh water?

A

Water in underground:
-streams
-rocks
-rivers
-lakes
-ice caps
-glaciers

52
Q

What is waste water?

A

Water used from homes , industry , and agriculture

53
Q

How can sea water be made potable?

A

-Distillation
-Reverse osmosis

54
Q

Why is sea water not able to become potable with water treatment?

A

Because it contains too many dissolved substances (salt) that cannot be removed by filtration

55
Q

What is the process used to make sea water drinkable called?

A

Desalination

56
Q

What makes distillation so costly?

A

-the evaporation of the water
-it uses too much energy

57
Q

What is reverse osmosis?

A

-water is pumped through a semi-permeable membrane (A TINY SIEVE WITH HOLES) that lets through comparatively small water molecules but not the much larger ions of the dissolved substances

58
Q

What is chlorine?

A

A poisonous gas that is used to kill microbes in water

59
Q

What is the test for chlorine?

A

Blue litmus paper turns red and is bleached white

60
Q

If chlorine is poisonous then why is it used in swimming pools and in treating drinking water?

A

-because it is used in small amounts
-because it’s not in a gas form

Chemistry (2 decks)

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