chemical analysis Flashcards

1
Q

definition of mixture

A

different substances mixed which are usually easy to separate

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2
Q

definition of a compound

A

different elements chemically joined together

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3
Q

definition of pure

A

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

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4
Q

how can u tell if a substance is pure

A

it has a sharp melting and boiling point

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5
Q

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

A

same

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6
Q

how is a formulation made

A

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

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7
Q

definition of a formulation

A

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

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8
Q

definition of a solute

A

solid that dissolves in a solvent

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9
Q

definition of a solvent

A

liquid into which a solute dissolves

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10
Q

definition of a solution

A

formed when a solute dissolves in a solution

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11
Q

how to separate salt from sand

A
  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
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12
Q

what do you draw the line with in chromatography and why

A

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

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13
Q

where is the pencil line drawn and why

A

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

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14
Q

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

A

there will only be one spot

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15
Q

mobile phase

A

solvent

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16
Q

stationary phase

A

the paper

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17
Q

what does rf stand for

A

retardation factors

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18
Q

rf=

A

distance moved by spot/distanced moved by solvent

19
Q

what is the liquid obtained in distillation

A

distillate

20
Q

what technique is used to separate a solvent from a solution

A

simple distillation

21
Q

how to separate miscible liquids

A

fractional distillation

22
Q

why does fraction distillation work to separate miscible liquids

A

this method works because the different liquids have different boiling points

23
Q

definition of miscible

A

liquids that mix together

24
Q

what do u use to separate immiscible liquids

A

separating funnel

25
Q

definition if immiscible liquids

A

liquids which do not mix together

26
Q

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

A

CuSO4.5H2O -> CuSO4 + 5H2O

27
Q

state the chemical test for water and describe the observations

A

anhydrous copper (II) sulphate
goes from white to blue

28
Q

why is water chlorinated

A

to sterilise it

29
Q

why is aluminium sulfate added in water treatment

A

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

30
Q

what is the purpose of anti-bumping granules in distillation

A

assist smooth boiling

31
Q

What is potable water

A

Water that is safe for human consumption

32
Q

How is group water made potable

A

Filtration
Sedimentation
Chlorination

33
Q

What are filter beds

A

Specially prepared layers of sand and gravel

34
Q

Where does the water go in filtration after passing filter beds

A

Sedimentation tank

35
Q

In filtration why is aluminium sulfate added

A

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

36
Q

What is chlorine added to water

A

To sterilise it

37
Q

How does chlorine sterilise water

A

Kills microbes

38
Q

How is pure water produced from seawater

A

Distillation

39
Q

What happens during distillation-seawater

A

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

40
Q

Disadvantages of producing drinking water from seawater

A

-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

41
Q

What do we use to test for water

A

Copper sulfate

42
Q

What colour does copper sulfate turn is water is present

A

White powder to blue crystals

43
Q

Equation for test for water

A

CuSO4 + 5H2O -> CuSO4.5H2O