chemical analysis

Question 1

definition of mixture

Answer 1

different substances mixed which are usually easy to separate

Question 2

definition of a compound

Answer 2

different elements chemically joined together

Question 3

definition of pure

Answer 3

a single element or compound that is not mixed with any other substance

Question 4

how can u tell if a substance is pure

Answer 4

it has a sharp melting and boiling point

Question 5

the freezing point of a pure substance is the _______ as its melting point

Answer 5

same

Question 6

how is a formulation made

Answer 6

by mixing the components in carefully measured quantities to ensure that the product has the required properties

Question 7

definition of a formulation

Answer 7

a mixture that has been designed as a useful product made by mixing the components in carefully measured quantities to ensure that the product has the required properties

Question 8

definition of a solute

Answer 8

solid that dissolves in a solvent

Question 9

definition of a solvent

Answer 9

liquid into which a solute dissolves

Question 10

definition of a solution

Answer 10

formed when a solute dissolves in a solution

Question 11

how to separate salt from sand

Answer 11

1. grind up rock salt mixture using a mortar and pestle
2. place rock salt into a beaker and acid and add 25 cm3 of water
3. stir using a stirring rod until all the salt has dissolved
4. filter the solution to removed the rock and sand and collect the filtrate in an evaporating basin
5. heat using a Bunsen, tripod and gauze to evaporate the water
6. allow to cool and crystallise

Question 12

what do you draw the line with in chromatography and why

Answer 12

pencil because if ink was used it could separate and interfere with the results

Question 13

where is the pencil line drawn and why

Answer 13

above the solvent otherwise the substances being tested would run into the solvent instead of travelling up the paper

Question 14

how do u know if it is a pure substance in chromatography

Answer 14

there will only be one spot

Question 15

mobile phase

Answer 15

solvent

Question 16

stationary phase

Answer 16

the paper

Question 17

what does rf stand for

Answer 17

retardation factors

Question 18

rf=

Answer 18

distance moved by spot/distanced moved by solvent

Question 19

what is the liquid obtained in distillation

Answer 19

distillate

Question 20

what technique is used to separate a solvent from a solution

Answer 20

simple distillation

Question 21

how to separate miscible liquids

Answer 21

fractional distillation

Question 22

why does fraction distillation work to separate miscible liquids

Answer 22

this method works because the different liquids have different boiling points

Question 23

definition of miscible

Answer 23

liquids that mix together

Question 24

what do u use to separate immiscible liquids

Answer 24

separating funnel

Question 25

definition if immiscible liquids

Answer 25

liquids which do not mix together

Question 26

write an equation for the dehydration of copper (II) sulfate

Answer 26

CuSO4.5H2O -> CuSO4 + 5H2O

Question 27

state the chemical test for water and describe the observations

Answer 27

anhydrous copper (II) sulphate goes from white to blue

Question 28

why is water chlorinated

Answer 28

to sterilise it

Question 29

why is aluminium sulfate added in water treatment

Answer 29

to clump tiny particles together to make larger particles, which settle out more easily

Question 30

what is the purpose of anti-bumping granules in distillation

Answer 30

assist smooth boiling

Question 31

What is potable water

Answer 31

Water that is safe for human consumption

Question 32

How is group water made potable

Answer 32

Filtration Sedimentation Chlorination

Question 33

What are filter beds

Answer 33

Specially prepared layers of sand and gravel

Question 34

Where does the water go in filtration after passing filter beds

Answer 34

Sedimentation tank

Question 35

In filtration why is aluminium sulfate added

Answer 35

To clump tiny particles together to make larger particles which settle out more easily

Question 36

What is chlorine added to water

Answer 36

To sterilise it

Question 37

How does chlorine sterilise water

Answer 37

Kills microbes

Question 38

How is pure water produced from seawater

Answer 38

Distillation

Question 39

What happens during distillation-seawater

Answer 39

The seawater is boiled The water vapour is then filled and condensed to firm pure water This leaves the salt behind

Question 40

Disadvantages of producing drinking water from seawater

Answer 40

-it’s is expensive because large amounts of energy is needed to heat the seawater - it increases the use of fossil fuels which are non renewable - carbon dioxide emissions from burning fossil fuels contributes to global warming

Question 41

What do we use to test for water

Answer 41

Copper sulfate

Question 42

What colour does copper sulfate turn is water is present

Answer 42

White powder to blue crystals

Question 43

Equation for test for water

Answer 43

CuSO4 + 5H2O -> CuSO4.5H2O