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chemistry paperrrrrr2 > Seperate Science 2 > Flashcards

Seperate Science 2 Flashcards

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1
Q

Flame tests are used to identify

A

Some metal ions

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2
Q

Method for flame tests

A

DIP a CLEAN WIRE LOOP into a SOLID sample to be tested
PUT loop in Bunsen burner BLUE FLAME
OBSERVE the flame colour

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3
Q

Flame colour of lithium

A

Crimson red

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4
Q

Flame colour of sodium

A

Yellow

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5
Q

Flame colour of potassium

A

Lilac

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6
Q

Flame colour of calcium

A

Orange - red

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7
Q

Flame colour of copper

A

Blue - Green

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8
Q

Why cant we use flame tests in samples containing a MIXTURE of ions

A

Flame colours can be masked

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9
Q

What method is used to identify metal ions in solutions

A

Metal hydroxide tests

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10
Q

Sodium hydroxide test in solution

A

Add sodium hydroxide to the solution
Observe the colour of the precipitate that forms

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11
Q

Aluminium colour precipitate

A

White

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12
Q

Calcium colour precipitate

A

White

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13
Q

Magnesium colour precipitate

A

White

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14
Q

Copper colour precipitate

A

Blue

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15
Q

Iron (II)

A

Green

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16
Q

Iron (III)

A

Brown

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17
Q

General formulaish for ionic equations in metal hydroxide tests

A

METAL ION with positive charge X + XOH- (charge number hydroxide ions) -> Metal(OH)x

Aq , aq, s

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18
Q

Aluminium charge

A

3+

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19
Q

calcium charge

A

2+

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20
Q

Magnesium charge

A

2+

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21
Q

Copper charge

A

2+

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22
Q

Aluminium calcium and magnesium all form white precipitates… how do we differentiate?

A

ADD AN EXCESS OF SODIUM HYDROXIDE and aluminium hydroxide precipitate will dissolve

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23
Q

How to test for ammonium

A

Add dilute sodium hydroxide
WARM mixture
Test for ammonia - damp red litmus paper will turn blue

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24
Q

Test for carbonates

A

React the carbonates with dilute acid - forming carbon dioxide
Bubble the gas through limewater
If it turns cloudy this confirms the presence of carbon dioxide and therefore a carbonate

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25
How do you test for halide ions
Add nitric acid and silver nitrate to solution
26
Product and observation when silver nitrate reacts with chloride
Silver chloride White precipitate Ag+ + Cl- -> AgCl
27
Product and observation when silver nitrate reacts with bromide
Silver bromide Cream precipitate Ag+ + br- -> agbr
28
Product and observation when silver nitrate reacts with iodide
Silver iodide Yellow precipitate Ag+ + i- -> AgI
29
How to test for sulfate ions
Add barium chloride solution and dilute hydrochloric acid
30
Positive test for sulfate ions
White precipitate forms Ba2+ + SO42- -> BaSO4
31
Advantages of instrumental methods
Accurate Sensitive Rapid
32
What can flame photometers do
Identify metal ions Work out the concentration of metal ions
33
How do flame photometers work
Split coloured light from a vaporised sample and produce an emission spectrum Every metal ion has its own unique emission spectrum
34
How do we determine concentrations of metal ions using flame photometers
1. Take reading at different known concentrations of the metal ion 2. Use the results to plot a calibration curve 3. You can now take a reading of a sample of unknown conc and use calibration curve to work out conc
35
Alkanes general formula
CnH2n+2
36
First four members of alkanes
Methane 1 carbon Ethane 2 Propane 3 Butane 4
37
Alkene
A hydrocarbon with a double carbon carbon bond!!
38
General formula of alkenes
CnH2n
39
What does it mean by alkenes are a saturated molecule
They have a double bond, so they have 2 fewer hydrogen atoms but same number of carbon atoms
40
First four alkenes
Ethene Propene Butene Pentene
41
Which is more reactive - alkanes or alkenes and proof
Alkenes!! They can react with bromine water
42
Test for alkenes
Add bromine water which is orange Alkene will decolourise the bromine water making it colourless
43
Combustion of hydrocarbons
Hydrocarbons are oxidised CH4 + 2O2 -> CO2 + 2H2O
44
Addition polymerisation
Many small molecules join together to form a very large molecule Poly(ethene) and poly(propene) for example
45
How do draw addition polymer
Break bond and draw square brackets around it with an n
46
Properties and uses of poly(ethene)
Cheap flexible Carrier bags cling film
47
Properties and uses of polypropene
Strong flexible resistant to shattering Plastic bowls and buckets
48
Polychloroethene - pvc
Can be made hard or flexible Tough Electrical insulator Insulation for electrical cables Guttering and pipes
49
Polytetrafluroethene - ptfe
Unreactive slippery Non stick pans
50
Condensation polymers
Uses monomers from 2 different functional groups They react and lose a small water eg water
51
What types of molecules react to form condensation reactions
Diols and dicarboxylic acids Diols is a molecule with 2 alcohol groups
52
What and how do diols and dicarboxylic acids react to make
Polymers -Oh group of diol reacts with the oh part of the -COOH group of the acid H20 is lost and bond forms Continues to repeat again and again
53
General equation of condensation polymers
n HO-[]-OH + n HOOC-[]-COOH -> (O-[]-O-CO-[]-CO)n + 2nH2O
54
Problems with polymers
Low availability of starting materials Non biodegradable so last for years in landfill If combusted they release carbon dioxide and toxic gases To recycle them they must be sorted before they can be melted and reformed - this is labour intensive and costly
55
A large molecule essential for life..
DNA!!!!! Contains genetic instruction 2 polymer chains made up of 4 different monomers called nucleotides in a double helix
56
4 main biological naturally occurring polymer
DNA Protein Starch Cellulose
57
DNA monomer and role
Nucleotides Provides code for genes Instructions needed for every living organism to stay alive
58
Protein monomer and role
Amino acids Many roles including making enzymes and hormones
59
Starch monomer and role
Sugar Stores energy in plants
60
Cellulose monomer and role
Sugar Strengthens cell walls in plant cells
61
Alcohols functional group
OH
62
Homologous series of alcohols
CnH2n+1 OH
63
Methanol molecular formula and use
CH3OH Chemical feedstock Added to industrial ethanol to stop people drinking it as its toxic
64
Ethanol molecular formula and use
C2H5OH Alcoholic drinks Fuel Solvent
65
Propanol molecular formula and use
C3H7OH Fuel solvent
66
Butanol molecular formula and use
C4H9OH Fuel solvent
67
Combustion of alcohols
Alcohol + oxygen -> carbon dioxide and water
68
Shorter alcohols are more efficient fuels because
They combust more easily They burn with a blue flame and release lots of energy
69
Alcohol + sodium
-> sodium alkoxide + hydrogen Bubbles will be observed
70
How can alcohols also be oxidised
With an oxidising agent
71
Alcohol + oxidising agent =
Carboxylic acid + water
72
As the chain length of alcohols increases, solubility
Decreases
73
How to make ethanol
Fermentation of glucose
74
Conditions required for fermentation
Sugar dissolved in water (glucose) Yeast No oxygen 25-35 degrees c so enzymes in yeast work properly Yeast and anaerobic conditions Glucose -> ethanol + carbon dioxide
75
Functional group of carboxylic acids
COOH
76
Homologous series representation of carboxylic acids
CH3COOH
77
Ph of carboxylic acids
Less than 7 Weak acids Partially ionise in water
78
How to make esters
Carboxylic acids react with alcohols Alcohol(ethanol) + carboxylic acid(ethanoic acid) -> ester (ethyl ethanoate example) + water
79
Functional group of esters
COO
80
What are esters used for
Solvents flavourings and perfumes as they have a fruity smell
81
Fractional distillation of ethanol
Fermentation contains yeast and other stuff that needs to bounce Water and ethanol solution heated Ethanol evaporates first Ethanol condenses Water has a different boiling point so evaporated and condenses later
82
Why can we use a Bunsen burner in heating ethanol
Ethanol is very flammable Use an electric heater
83
What are nano particles
Particles between 1-100nm in size, made up of a few hundred atoms
84
Size and order of different particles
Atoms 1 x 10-10m Nano particles 1 x 10-9m - 1 x 10-7m Fine particles(PM2.5) 1 x 10-7m - 2.5 x 10-6m Coarse particles(PM10) 2.5 x 10-6m - 1 x 10-5 m
85
Uses of nano particles
Medicines Electronics Cosmetics Sun creams Deodorants Catalysts
86
Why are nano particles so darn useful
Large surface area to volume ratio
87
Risks of nano particles
Can be breathed in Enter cells Catalyse harmful reactions Toxic substances could bind to them
88
clay ceramics
Make bricks and pottery Shaping wet clay and then heating to cause crystals to form and join together Brittle hard and resistant to corrosion
89
Glass ceramics 2 types
Main type used is soda lime glass sometimes borosilicate glass is used
90
Soda lime glass
Mixture of sand sodium carbonate and limestone heated Brittle and transparent Everyday glass objects
91
Borosilicate glass
Sand heated with boron trioxide High melting point Laboratory glassware and ovens

chemistry paperrrrrr2 (4 decks)

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