Seperating Mixtures + Water Treatment - Term 2

Question 1

Name the 3 separation techniques

Answer 1

Filtration , Evaporation and Crystallisation

Question 2

Soluble

Answer 2

A solid that can dissolve

Question 3

Insoluble

Answer 3

A solid that cannot dissolve

Question 4

Filtration

Answer 4

insoluble solid from a liquid + a liquid from an insoluble solid.

Question 5

Solute

Answer 5

Solid part of a solution

Question 6

Solvent

Answer 6

Liquid part of a solution

Question 7

Crystallisation

Answer 7

Separation of soluble solid from solution (often used when making crystals with a solution where the solvent is water)
Solution is left in a warm place to evaporate slowly . When solution becomes saturated , crystals appear, which are said to be hydrated.

Question 8

Evaporation

Answer 8

Solute from a solution.
(eg salt from salt water)

Question 9

Example of filtration

Answer 9

Separation of sand and water

Question 10

Examples of evaporation

Answer 10

Strongly heating copper sulfate + water solution

Question 11

Examples of crystallisation

Answer 11

Leaving copper sulfate + water solution in a crystallisation dish undisturbed

Question 12

Conclusion from seperating copper sulfate and sand experiment

Answer 12

Quick evaporation = white powdered copper sulfate
Slow evaporation ( crystallisation) = hydrated copper sulfate crystals

Question 13

Explain how simple distillation works

Answer 13

A flask containing the solution is heated. As the solvent evaporates , the vapor goes into the condenser. The condensor cools the vapor into liquid and this liquid drips into the beaker.

Question 14

distillate

Answer 14

end result of distillation

Question 15

when is simple distillation used

Answer 15

solvent from a solution

Question 16

when is fractional distillation used

Answer 16

mixture of miscible liquids

Question 17

explain how fractional distallation works

Answer 17

• mixture is heated to (lower boiling point)
• liquid with lower boiling point evaporates first
• condenses in the condesor

Question 18

distilate

Answer 18

end result of distilation

Question 19

miscible

Answer 19

liquids that can mix together

Question 20

immiscble

Answer 20

liquids that cant mix together

Question 21

example of two miscible liquids

Answer 21

alcohol and water

Question 22

example of two immiscble liquids

Answer 22

paraffin and water

Question 23

how to separate immiscble liiquids

Answer 23

a separating funnel

Question 24

how does a separating funnel work

Answer 24

the liquid of higher density is placed under a liquid of lower density. you open the hole and the liquid of higher density (eg water) flows out first. you then switch beakers and drain the remaining liquid of lower density (eg parafin)

Question 25

what is chromatography used for

Answer 25

separate several solids that are all soluble in the same solvent

Question 26

how does chromatography work

Answer 26

the pigment is placed near the bottom of the chromatography paper and placed in the solvent (such as water). the pigment moves up the paper at different rates due to levels of solubility.

Question 27

the more soluble the pigment is..

Answer 27

the higher it'll be on the paper / the faster it'll move up the paper

Question 28

the less soluble the pigment is...

Answer 28

the lower it'll be on the paper / the slower it'll move up the paper

Question 29

solvent ________ phase

Answer 29

mobile

Question 30

paper ________ phase

Answer 30

stationary

Question 31

solvent front

Answer 31

highest point reached by solvent

Question 32

start point

Answer 32

where spot is originally placed

Question 33

why is the start point marked in pencil and not pen

Answer 33

so the ink from the pen doesn't run along the rest of the spots

Question 34

why are spots often labelled at the start

Answer 34

the colors can greatly change so you should still be able to tell them apart

Question 35

why must the water level be below the spots

Answer 35

so the spots don't just dissolve into the liquid in the beaker

Question 36

what are Rf values used for

Answer 36

to identify different substances

Question 37

formula for Rf

Answer 37

distance moved by pigment (measured from centre of spot) / distance moved from start line to solvent front

Question 38

how do you tell if two dyes are the same

Answer 38

if they moved the same amount

Question 39

how can you tell the number of original dyes in the sample

Answer 39

number of spots above starting point

Question 40

decanting

Answer 40

Insoluble solid from a liquid + liquid from an insoluble solid

Question 41

why do we treat water

Answer 41

so it is drinkable

Question 42

potable water =

Answer 42

water that is safe to drink

Question 43

why do we treat water (what to remove)

Answer 43

remove insoluble solids and harmful bacteria

Question 44

why is treated water not pure

Answer 44

pure water is just hydrogen and oxygen. treated water contains minerals needed for health

Question 45

3 steps of water treatment

Answer 45

sedimentation filtration sterilization

Question 46

what happens during sedimentation

Answer 46

water is left to be still in a tank insoluble solids settle to the bottom water is removed from higher up the tank

Question 47

what happens during filtration in water treatment

Answer 47

sand filters remove smaller particles of insoluble solids

Question 48

what happens during sterilization

Answer 48

chlorine is added to kill bacteria. ozone and uv lights can also be used.

Question 49

treatment of sea water

Answer 49

- cannot use og method because contains too many dissolved particles - use distillation or reverse osmosis

Question 50

reverse osmosis

Answer 50

- applying pressure to untreated salt water, it is forced through a semi permeable membrane which only allows water molecules through the other side

Question 51

why is producing drinking water from sea water more expensive

Answer 51

high energy

Question 52

equation for anhydrous copper sulfate to hydrated copper sulfate

Answer 52

CuSO4 + 5h2O ---> CusO4 . 5h2O

Question 53

why is distilled water used in experiments

Answer 53

dissolved particles in tap water may react

Question 54

test for chlorine litmus paper

Answer 54

damp blue litmus paper goes red and then bleaches

Question 55

separate a mixture of insoluble solid and soluble solid

Answer 55

- add water - filter for insoluble solid - evaporate for soluble solid

Question 56

what does it mean if the spot has moved less up the paper

Answer 56

it spent more time in the stationary phase and is more attracted to the paper

Question 57

what can be used to measure volume of sea water

Answer 57

measuring cylinder

Question 58

why is it more difficult to produce drinking water from waste water than from water in lakes

Answer 58

- more microbes - more toxic chemicals - more organic matter

Question 59

how could water be tested to make sure its pure

Answer 59

boiling point of 100 and freezing point of 0