Separating Mixtures And Water Treatment

Question 1

What does soluble mean?

Answer 1

A substance that will dissolves in fluid to form a solution

Question 2

What does insoluble mean?

Answer 2

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

Question 3

What is a solute?

Answer 3

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

Question 4

What is a solvent?

Answer 4

A substance that dissolves a solute (usually liquid)

Question 5

What is filtration?

Answer 5

Filtration separates an insoluble solid from a liquid

Question 6

How does filtration work?

Answer 6

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

Question 7

What is decantation?

Answer 7

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

Question 8

How does decantation work?

Answer 8

A liquid is poured very slowly leaving the solid behind

Question 9

What is evaporation?

Answer 9

Evaporation is used to separate a soluble solid from a solution

Question 10

How does evaporation work?

Answer 10

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

Question 11

What is crystallisation?

Answer 11

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

Question 12

How does crystallisation work?

Answer 12

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

Question 13

Describe the crystals produced from crystallisation

Answer 13

-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)

Question 14

Describe copper sulfate:

Answer 14

-blue
-copper gives it its crystal structure

Question 15

What is distillation?

Answer 15

the process of separating a solvent from a solution

Question 16

What is a condenser?

Answer 16

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

Question 17

At what temperature does water distil off?

Answer 17

100 degrees Celsius

Question 18

What do anti-bumping granules do ?

Answer 18

Prevent the formation of large gas bubbles that cause violent boiling

Question 19

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

Answer 19

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

Question 20

What is pure water?

Answer 20

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

Question 21

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

Answer 21

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

Question 22

What is are miscible liquids?

Answer 22

Two liquids that mix
(Eg alcohol and water)

Question 23

How are miscible liquids separated?

Answer 23

Using fractional distillation

Question 24

How does fractional distillation work?

Answer 24

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

Question 25

What are immiscible liquids?

Answer 25

Liquids that do not mix and form separate layers

Question 26

Examples of miscible liquids:

Answer 26

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

Question 27

Example of immiscible liquid:

Answer 27

Oil and water

Question 28

How are immiscible liquids separated?

Answer 28

Using a SEPARATING FUNNEL -The liquid with a LOWER density stays at the top (e.g oil) -The liquid with a HIGHER density stays at the bottom (e.g water)

Question 29

Example of decanting and filtration:

Answer 29

Sand and water

Question 30

Example of evaporation:

Answer 30

Salt from salt solution

Question 31

Examples of distillation:

Answer 31

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

Question 32

What is chromatography?

Answer 32

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

Question 33

What can be separated using chromatography?

Answer 33

- Dyes - Inks

Question 34

How does chromatography work?

Answer 34

- Dyes are placed at the bottom of the chromatography paper - This is then placed in a SOLVENT (e.g water) - As the water is drawn up the paper it moves different dyes at different rates depending on their SOLUBILITY in water

Question 35

How do you know which dyes are more soluble?

Answer 35

- 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

Question 36

What is the solvent and paper referred as?

Answer 36

Paper - stationary phase solvent - mobile phase

Question 37

How do you work out the Rf value?

Answer 37

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

Question 38

Why is the 1cm line drawn in pencil?

Answer 38

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

Question 39

Why are the spots labelled at the start?

Answer 39

Because they become unrecognisable after they separate

Question 40

Why MUST the water level be below the spots?

Answer 40

So that the ink doesn’t dissolve into the water

Question 41

What does the chromatography tell you about the pens?

Answer 41

Most inks are made up of two or more colours

Question 42

What is water suitable for drinking called?

Answer 42

Potable

Question 43

What is water treatment?

Answer 43

The process of making water safe to drink

Question 44

What does water treatment do?

Answer 44

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

Question 45

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

Answer 45

-sedimentation -filtration -sterilisation

Question 46

How does sedimentation work?

Answer 46

-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

Question 47

What are coagulants?

Answer 47

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

Question 48

How does filtration work?

Answer 48

-Water is passed through a series of sand filters -The sand filters removes particles of insoluble/dissolved solid

Question 49

How does sterilisation work?

Answer 49

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)

Question 50

What is ground water?

Answer 50

Water in underground streams and rocks

Question 51

What is fresh water?

Answer 51

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

Question 52

What is waste water?

Answer 52

Water used from homes , industry , and agriculture

Question 53

How can sea water be made potable?

Answer 53

-Distillation -Reverse osmosis

Question 54

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

Answer 54

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

Question 55

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

Answer 55

Desalination

Question 56

What makes distillation so costly?

Answer 56

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

Question 57

What is reverse osmosis?

Answer 57

-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

Question 58

What is chlorine?

Answer 58

A poisonous gas that is used to kill microbes in water

Question 59

What is the test for chlorine?

Answer 59

Blue litmus paper turns red and is bleached white

Question 60

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

Answer 60

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