Extension Flashcards
(121 cards)
1
Q
What is qualitative analysis?
A
It investigates what kind of substances are present
2
Q
What is quantitative analysis?
A
It measures the amount of substances present
3
Q
What colour is calcium in the flame test?
A
Brick red
4
Q
What colour is sodium in the flame test?
A
Yellow
5
Q
What colour is potassium in the flame test?
A
Lilac
6
Q
What colour is copper in the flame test?
A
Green/blue
7
Q
What colour precipitate forms as a result of aluminium being added to sodium hydroxide?
A
White
8
Q
What colour precipitate does calcium form in sodium hydroxide?
A
White
9
Q
What colour precipitate is formed when copper is added to sodium hydroxide?
A
Pale blue
10
Q
What colour precipitate is formed when Iron (II) is added to sodium hydroxide?
A
Green
11
Q
What colour precipitate is formed when Iron (III) is added to sodium hydroxide?
A
Brown (rust)
12
Q
How is calcium distinguished from aluminium when undertaking cation tests?
A
Add excess sodium hydroxide and aluminium ion precipitate will dissolve to a colourless solution
13
Q
What colour does chloride ion turn in silver nitrate (that has been acidified with dilute nitric acid)?
A
White
14
Q
What colour does bromide ion turn in silver nitrate?
A
Cream
15
Q
What colour does iodide ion turn in silver nitrate?
A
Yellow
16
Q
What is the test for ammonium?
A
Warming it with sodium hydroxide, a gas will be given off and it will turn damp red litmus paper blue
17
Q
What do analytical chemists do for water authorities?
A
They check the purity of water against the government standards
18
Q
What are aluminium salts added to water for?
A
To remove small particles of solids
19
Q
Why is sodium fluoride added to water?
A
As it has been shown to reduce tooth decay
20
Q
What have high levels of aluminium been linked to?
A
Alzheimer’s disease and damage to the digestive system
21
Q
What are low levels of iron linked to (in terms of illness)?
A
Anaemia
22
Q
What are high levels of sodium linked to in terms of illness?
A
High blood pressure and kidney disease
23
Q
Name two ions that make water ‘hard’?
A
Calcium and magnesium
24
Q
What is concentration measured in?
A
Grams per cubed decimetre
25
What does hard water make it difficult for soap to do and what is formed as a result?
To lather, scum is formed instead
26
How is temporary hard water softened?
By heating it
27
What method works to make permanent hard water soft?
An ion exchange column
28
What is the ion exchange column packed with?
Tiny plastic beads made of a special 'resin'
29
What happens when the hard water is passed through the ion exchange column?
The calcium and magnesium ions swap with the sodium ions that are weakly attached to the resin
30
What number of atoms are always present in an element?
Avogadro's number - 6.02 X 10^23
31
What is one mole?
It is the amount that contains an Avogadro's number of the named particles
32
What is the equation for working out moles?
Moles = grams/RAMs
33
What is the formula for concentration in mol dm^-3
Number of moles / volume of solution
34
Describe the five stages of making copper sulfate crystals
1) add the base (copper oxide) in sulfuric acid until no more reacts
2) warm the mixture
3) filter unreacted solid
4) leave to cool and crystallise
5) filter off crystals and leave to dry
35
What indicator should be used in a titration experiment?
Phenolphthalein
36
What does the Burette allow for in a titration experiment?
For the acid to be added drop by drop until the indicator turns colourless
37
After the volume needed for neutralisation in a titration has been discovered what happens next?
The reaction is repeated without indicator
38
When an acid dissolves in water, what does it form?
Hydrogen ions
39
What a soluble base dissolves in water, what ions does it form?
Hydroxide ions
40
What happens in terms of ions in a neutralisation reaction?
The hydrogen ions and hydroxide ions combine to form water molecules
41
How do you turn a value from centimetres to decimetres?
Divide by 1000
42
Define the term electrolytes
An ionic substance that conducts electricity when in aqueous solution or when molten
43
What are cations attracted to in electrolysis?
The negative cathode
44
What are anions attracted to in electrolysis?
The positive anode
45
What is the anagram OIL RIG?
Oxidation is loss (of electrons)
| Reduction is gain (of electrons)
46
What are two uses of sodium?
In street lamps as sodium vapour gives out a bright yellow light when an electric current is passed through it
As a coolant in nuclear reactants as liquid sodium metal has a high thermal conductivity and transfers heat efficiently from the reactor to water which then drives the generators
47
Show the half equations of sodium chloride in electrolysis
At the cathode: 2Na+ + 2e- --> 2Na
At the anode: 2Cl- --> Cl2 + 2e-
48
In the electrolysis of copper chloride what is formed at the cathode and anode?
Copper is at the cathode as it gains electrons
| Chloride is at the anode as it loses electrons
49
What is found at the anode and cathode in the electrolysis of copper sulfate?
Copper at the cathode
| Hydroxide at the anode which then forms water and oxygen (this is because hydroxide ions are more readily discharged)
50
What is found at the anode and cathode in the electrolysis of sodium sulfate?
Anode is oxygen and water
| Cathode is hydrogen as hydrogen ions lose charge more readily than sodium
51
Why is graphite used as electrodes?
Because it is a good conductor and inert
52
What is formed at anode and cathode in the electrolysis of salt water?
Cathode: it is easier to discharge hydrogen than sodium
Anode: chlorine gas is discharged
53
What is the third product of electrolysis of salt water?
Sodium hydroxide solution
54
Where is the impure copper placed, as the anode or cathode?
Anode
55
Where is the pure copper placed, as anode or cathode?
Cathode
56
Which copper rod plates the other?
The impure copper anode plates the pure copper cathode
57
Mass lost at the anode is gained where?
At the cathode
58
Where do the impurities form in the process of the electrolysis?
At the bottom of the beaker as sludge
59
What is electroplating?
It is depositing a thin layer of one metal on the surface of another through electrolysis
60
Which electrode is the pure metal and which is the one being plated?
The anode is the pure metal and the cathode is the one being played
61
How is a thicker layer achieved? (In electroplating)
By increasing current or carrying out the process for longer
62
What are two things that electroplating is used to improve?
Appearance and resistance to corrosion
63
What is the application of electroplating silver?
Cutlery and sports trophies
64
What is the application of electroplating gold?
Jewellery
65
What is the application of electroplating with chromium?
Wheel rims and jewellery
66
What is the use for electroplating tin?
For steel food cans
67
What is zinc used to electroplate for?
Iron nails and steel railings
68
What is the molar volume of gas?
24dm^3
69
Under what conditions does a gas have to be under to have the molar volume of gases?
At room temperature and normal atmospheric pressure (1 atmosphere)
70
What is ammonia used for?
To make nitrogenous fertilisers
71
Through what process is ammonia made artificially?
The haber process
72
What kind of reaction is the one used in the haber process?
A reversible reaction
73
How are nitrogen and hydrogen provided for the haber process?
Nitrogen is extracted from air and hydrogen is produced from methane
74
Name an advantage and disadvantage of the use of nitrogenous fertilisers that are manufactured from the haber process
More crops can be made and more quickly
| Eutrophication
75
What kind of reactions are the forward and backwards reaction in the haber process?
Forward - exothermic
| Backward - endothermic
76
What does it mean for the reaction to be in dynamic equilibrium?
It means the forward and backwards reaction happen at the same rate
77
How is the equilibrium in the haber process shifted to the right?
By increasing pressure and decreasing temperature
78
What is the usual pressure used in the haber process?
200 atmospheres
79
Why is the haber process not maintained at a higher pressure than 200 atmospheres?
Because the equipment is expensive to produce and maintain
80
Why is a high temperature used in the haber process and why isn't it higher than 450 degrees?
To increase rate of reaction but isn't to high that it favours the backwards reaction
81
What is present in the haber process?
An iron catalyst
82
Why can alcohol not be made at a higher concentration than 15% in a fermenter?
Because the high concentration of ethanol will kill the yeast
83
How is high concentration alcohol made?
Through fractional distillation
84
What temperature does ethanol boil at and why does this mean it can be made more concentrated?
At 78 degrees which means the fraction that boils first contains a higher percentage of ethanol
85
What is in the fractioning column which will condense some of the vapour?
Glass beads
86
What is used to condense the ethanol?
A condenser
87
What percentage of ethanol will be in the condensed liquid after the process of fractional distillation?
Up to 95%
88
What is the reaction for ethanol production in a fermenter?
Glucose ---> (presence of yeast) ethanol + CO2
89
How does ethene react to form ethanol?
It is hydrated
Ethene + steam ---> (catalyst) ethanol
90
What is the advantage of producing ethanol from ethene over fermentation?
It produces ethanol that is almost 100% pure
91
How ethene produced from ethanol?
It is dehydrated in the presence of a catalyst at a high temperature to form ethene and steam
92
What is a homologous series?
A family of compounds that all have the same feature but have different numbers of carbon atoms
93
What is the general formula for alkenes?
C n H 2n
94
What is the difference between the bonding of alkenes and alkanes?
Alkenes contain a double bond
95
How do you test for if a substance is an alkene or alkane?
An alkene will turn bromine water colourless
96
Methanol, ethanol and propanol all belong to which homologous series?
The alcohols
97
What group do alcohols contain?
The hydroxyl group
98
What is the general formula for alcohols?
C n H 2n+1 OH
99
Why do alcohols burn with a cleaner blue flame than hydrocarbons?
Due to the hydroxide
100
How is ethanoic acid made?
Through the oxidation of ethanol
101
What taste does ethanoic acid give food?
Tangy and sharp
102
What does ethanoic acid work as in terms of storing food?
A preservative
103
Why can ethanoic acid be sued as a preservative?
Because bacteria can't survive in the acidic environment
104
What homologous series does ethanoic acid belong to?
Carboxylic acids
105
Describe three properties of ethanoic acids
Turn litmus paper and universal indicator red
React with some metals to make hydrogen
React with bases to form salts called 'ethanoates'
106
What group do carboxylic acids contain?
Carboxyl group
107
What does the carboxyl group mean for the molecule of the carboxylic acids?
That they contain -COOH
108
Name 2 uses for esters
Perfumes and flavourings
109
How are esters made?
When carboxylic acids react with esters
110
What two products are formed from the reaction between an alcohol and a carboxylic acid?
An ester and water
111
What is a polyester?
A long chain ester
112
What is a use for polyesters?
They are used in plastics and as fibres for fabrics
113
What are oils and fats?
Large esters
114
What is the difference between an oil and a fat?
A fat is solid at room temperature and oil is a liquid
115
What happens when glyceryl tristearate is boiled with an alkali?
The fat breaks down to glycerol and sodium stearate (a soap)
116
What is the general equation for making a soap?
Concentrated alkali + oil/fat --> soap + glycerol
117
Name two alkalis used in soap production
Sodium hydroxide and potassium hydroxide
118
Which part of the soap is hydrophillic?
The 'head' (it is an anion)
119
Which part of the soap is hydrophobic?
The 'tail'
120
How does soap remove grease?
The hydrophobic tail sticks into the grease and gets underneath the grease and pulls it off the surface, the hydrophillic head then allows the grease to mix with the water
121
Describe catalytic hydrogenation
An unsaturated hydrocarbon is reacted with hydrogen to form a saturated hydrocarbon, this usually happens on the presence of a nickel catalyst
