separation techniques (+acids & alkalis)

Question 1

concentration equation + units

Answer 1

c(g/dm^3) = m(g) / v(dm^3)

Question 2

cm^3 to dm^3

Answer 2

divide by 1000

Question 3

dm^3 to cm^3

Answer 3

x 1000

Question 4

which technique is used for a mix of insoluble solids from liquids

Answer 4

filtration

Question 5

mixtures can be separated by….. not involving…..

Answer 5

physical processes, chemical reactions

Question 6

what technique is used to separate soluble solids from liquids

Answer 6

crystallisation

Question 7

what technique is used to separate solvent from solution

Answer 7

distillation

Question 8

what technique is used to separate miscible liquids

Answer 8

fractional distillation

Question 9

which technique is used to separate a mixture of soluble solids

Answer 9

chromatography

Question 10

what part of paper chromatography is the stationary phase

Answer 10

paper

Question 11

what’s the mobile phase in paper chromatography

Answer 11

solvent

Question 12

Rf=

Answer 12

distance travelled by sample / distance travelled by solvent

Question 13

what is potable water

Answer 13

safe to drink

Question 14

where is waste water from

Answer 14

homes, agriculture + industry

Question 15

where’s ground water from

Answer 15

aquifers

Question 16

where’s surface water from

Answer 16

lakes, rivers + reservoirs

Question 17

what is the point of filtering water

Answer 17

to remove solids

Question 18

what’s the point of sterilising water

Answer 18

kills microbes

Question 19

what 2 stages does surface + ground water treatment involve

Answer 19

filtration + sterilisation

Question 20

forms of sterilisation (3)

Answer 20

-add chlorine
-treat with ozone
-use UV light

Question 21

what process turns sea to potable water

Answer 21

desalination by distillation

Question 22

why don’t we use sea water often

Answer 22

distillation is expensive

Question 23

what is the 1st step of waste water treatment

Answer 23

1.filtration- wire mesh screens out large debris, then fine filter (gravel/sand beds) filter out solids

Question 24

what’s the 2nd step of waste water treatment

Answer 24

sedimentation- iron sulfate or aluminium is added which causes fine particles to clump together + settle at bottom

Question 25

what’s the 3rd step of waste water treatment

Answer 25

chlorination- chlorine gas is bubbled through to kill harmful bacteria + microbes

Question 26

what is deionised water and why do we use it

Answer 26

-had the ions removed
-bc tap water could react with other chemicals during experiments

Question 27

what pH do acids have

Answer 27

7>

Question 28

a low pH means…

Answer 28

high conc of H+ ions

Question 29

what pH do alkalis have

Answer 29

7<

Question 30

a high pH means …

Answer 30

low conc of H+ ions

Question 31

what is the pH of a neutral solution

Answer 31

7

Question 32

what are 5 pH indicators

Answer 32

-universal indicator
-pH meter
-litmus paper
-methyl orange
-phenolphthalein

Question 33

what is pH a measure of

Answer 33

H+ ions

Question 34

if pH decrease by 1 unit, conc of H+ …

Answer 34

increases by factor of 10

Question 35

If conc of H+ ions decreases by 10….

Answer 35

pH increase by 1

Question 36

why does adding an alkali increase pH

Answer 36

bc it decreases number of H+ ions as it produces OH- ions which react with H+ ions to produce H2O

Question 37

if volume increases concentration….. and pH …..

Answer 37

decreases, increases

Question 38

if volume decreases conc …. and pH ….

Answer 38

increases, decreases