Topic 9: Seperate Chemistry 2 Flashcards
(111 cards)
1
Q
What is the test for sulfates?
A
- Add dilute hydrochloric acid (to remove any carbonate ions that might obscure results) and barium chloride solution to a solution
- If sulfate ions are present, a white precipitate of barium sulfate will form
2
Q
What is the test for chloride?
A
- Add nitric acid and silver nitrate solution to a solution
- If chloride ions are present, a white precipitate will form of silver chloride
3
Q
What is the test for bromide?
A
- Add nitric acid and silver nitrate solution to a solution
- If bromide ions are present, a cream precipitate will form of silver bromide
4
Q
What is the test for iodide?
A
- Add nitric acid and silver nitrate solution to a solution
- If iodide ions are present, a yellow precipitate will form of silver iodide
5
Q
What are the 3 halides you need to know tests for?
A
- Chloride
- Bromide
- Iodide
6
Q
What is the test for carbonates?
A
- Add a couple of drops of a dilute acid to a solution which will fizz if carbonate ions are present
- Connect the test tube with the solution to a test tube with limewater
- If carbonate ions are present, the limewater will turn milky as carbon dioxide will be formed (and limewater turns cloudy/milky when carbon dioxide is present)
7
Q
What is the test for metal cations?
A
- Add a few drops of sodium hydroxide to a solution
- The colour of the precipitate that forms depends on the metal ion in the solution
8
Q
When testing for metal cations using sodium hydroxide, what colour is the precipitate formed if calcium is present in the solution?
A
White
9
Q
When testing for metal cations using sodium hydroxide, what colour is the precipitate formed if copper (II) is present in the solution?
A
Blue
10
Q
When testing for metal cations using sodium hydroxide, what colour is the precipitate formed if iron (II) is present in the solution?
A
Green
11
Q
When testing for metal cations using sodium hydroxide, what colour is the precipitate formed if iron (III) is present in the solution?
A
Brown
12
Q
When testing for metal cations using sodium hydroxide, what colour is the precipitate formed if aluminium is present in the solution?
A
White
BUT with excess NaOH, the precipitate re-dissolves to form a colourless solution
13
Q
What is the test of ammonium ions?
A
- Add sodium hydroxide solution to the solution you’re testing and gently heat
- If ammonium ions are present, ammonia gas will be given off
- Ammonia gas turns damp red litmus paper blue - so that how you can check if ammonium ions are present
14
Q
What colour does a flame turn in a flame test if calcium ions are present in the sample?
A
Orange-red flame
15
Q
What colour does a flame turn in a flame test if sodium ions are present in the sample?
A
Yellow flame
16
Q
What colour does a flame turn in a flame test if potassium ions are present in the sample?
A
Lilac flame
17
Q
What colour does a flame turn in a flame test if lithium ions are present in the sample?
A
Crimson flame
18
Q
What colour does a flame turn in a flame test if copper ions are present in the sample?
A
Blue-green flame
19
Q
Disadvantages of flame tests?
A
If the sample contains a mixture of metal ions, the flame colours of some ions may be hidden by the colours of other - may not give you the correct results
20
Q
What is instrumental analysis?
A
Tests that use machines
21
Q
3 advantages of instrumental analysis?
A
- Sensitive - can detect even the tiniest amounts of ions
- Fast - tests can be automated
- Accurate - don’t involve human error
22
Q
What are 2 uses of flame photometry?
A
- Identifying ions in solution
- Determining the concentration of ions
23
Q
How does flame photometry identify ions in a solution?
A
Each ions produces a unique line spectrum - allows you to compare with a reference spectra
24
Q
How can flame photometry determine the concentration of ions?
A
The intensity of the lines on the spectrum can allow this to be calculated:
1. Find the intensity that’s been measured on the graph
2. Correspond this to the concentration using the calibration curve (line on the graph)
25
What is flame photometry an example of?
Instrumental analysis
26
If multiple ions are present in the sample in flame photometry, what happens to the spectrum?
The spectrum will be a combination of all of the ions’s individual spectra
27
What are alkanes?
The simplest type of hydrocarbons, containing only single covalent bonds
28
What is the general formula for alkanes?
CnH2n+2
29
Are alkanes saturated or unsaturated? Why?
They’re saturated - all the atoms have formed single covalent bonds with as many other atoms as possible
30
What are the first 4 alkanes in the alkane homologous series? WITH FORMULAS
Methane CH4
Ethane C2H6
Propane C3H8
Butane C4H10
31
How to remember the order of the first 4 compounds in all hydrocarbon homologous series?
Monkeys
Eat
Pink
Bananas
32
What is an alkene?
Hydrocarbons that have one C=C double bond functional group
33
What is a functional group?
A group of atoms in a molecule that dictate how that molecule typically reacts
34
Are alkenes saturated or unsaturated? Why?
Unsaturated - the double bind can open up to form other bonds
35
What are the first 3 alkenes in the alkene homologous series? WITH FORMULAS
Ethene C2H4
Propene C3H6
Butene C4H8
NO METHENE BECAUSE AN ALKENE NEEDS TO HAVE AT LEAST 2 CARBONS TO HAVE A CARBON DOUBLE BOND AND METHENE WOULD ONLY HAVE 1 CARBON MOLECULE
36
What can happen to the double bond in alkenes in addition reactions?
It opens up - another substance adds across the double C=C bond
37
What is the test for alkenes?
1. Add solution to bromine water
2. Shake the mixture
3. If the mixture turns colourless, alkene is present
38
If an alkane is added to bromine water, what happens?
Nothing - the bromine water remains orange (doesn’t turn colourless like it does for alkenes)
39
What is the equation for combustion of hydrocarbons?
Hydrocarbon + oxygen —> carbon dioxide + water
40
What are polymers?
Substances made by joining lots of small repeating units (monomers), they have a high average Mr
41
What is addition polymerisation?
When molecules with C=C bonds join together in addition reactions
42
Describe the process of addition polymerisation?
1. A monomer (e.g. ethene) will open up its carbon double bond
2. This will then allow the same monomers to join up to each other and form a polymer (e.g. poly(ethene))
43
What are polymers named after?
The monomers that they’re formed from
44
Describe the steps of drawing the displayed formula of a polymer from its monomer
1. Draw the alkene carbons and replace the double bond with a single bond
2. Add an extra single bond to each carbon atom
3. Add the other groups in the same way that they surround where the double bond was
4. Add brackets and an ‘n’ at the bottom
45
What are the properties of poly(ethene)?
Flexible
Cheap
Electrical insulator
46
What are the uses of poly(ethene)?
Carrier bags
Wire insulation
47
What are the properties of poly(propene)?
Flexible
Strong
Tough
Mouldable
48
What are the uses of poly(propene)?
Plastic crates
Ropes
49
What are the properties of poly(chloroethene)?
Tough
Cheap
50
What are the uses of poly(chloroethene)?
Window frames
Water pipes
51
What is poly(chloroethene) also known as?
PVC
52
What are the properties of poly(tetrafluoroethene)?
Unreactive
Tough
Non stick
53
What are the uses of poly(tetrafluoroethene)?
Non stick pans
Waterproof clothing
54
What is poly(tetrafluoroethene) also known as?
PTFE
55
What is condensation polymerisation?
Polymers formed from monomers with two functional groups where a by product of the polymerisation is water
56
What is the equation for condensation polymerisation?
Diol + dicarboxylic acid —> polyester + water
57
What are 3 natural polymers?
1. DNA
2. Starch
3. Proteins
58
What is DNA?
A complex molecule that contains genetic material
59
What is the monomer that forms DNA?
Nucleotides
60
What is starch?
A polymer made from sugars
61
What is the monomer that forms starch?
Sugars
62
What are proteins?
Condensation polymers of amino acids
63
What is the monomer that makes proteins?
Amino acids
64
What are the uses of protein in the body?
Are in enzymes
65
Advantages of recycling plastics?
Less plastics have to be disposed of - results in less non biodegradable waste going to landfill & also in less carbon dioxide and toxic gases being related by burning plastics
Generally uses less resources than making new plastics - made from crude oil (finite resource)
Generally saves money and creates jobs
66
Disadvantages of recycling plastics?
Must be separated before melting down - difficult and expensive
Melting down can still release polluting gases
Over time, strength of polymer decreases - can’t recycle the same polymer forever
67
What is an alcohol?
A compound containing -OH functional group
68
How can alkenes be made from alcohols?
Heating alcohol with an acid a catalyst - this is a dehydration reaction as a molecule of water is lost from the alcohol
69
What are the names of the first 4 alcohols in the alcohol homologous series? WITH FORMULA
Methanol CH3OH
Ethanol C2H5OH
Propanol C3H7OH
Butanol C4H9OH
70
What is the the general formula for alcohols?
CnH2n+1OH
71
What is a Carboxylic acid?
A compound containing a -COOH functional group
72
What do Carboxylic acids have the same properties as?
Weak acid solutions
73
How can Carboxylic acids be made from alcohols?
If alcohols are oxidised - e.g. ethanol can be oxidised to form ethanoic acid
74
Why do members of a homologous series have similar reactions?
They have the same functional group
75
What are the names of the first 4 Carboxylic acids in the Carboxylic acid homologous series? WITH FORMULA
Methanoic acid HCOOH
Ethanoic acid CH3COOH
Propanoic acid C2H5COOH
Butanoic acid C3H7COOH
76
What is fermentation?
Process where a yeast enzyme converts solutions of carbohydrates (e.g. sugars) into alcohol
77
What is the equation for fermentation?
Sugar —yeast—> ethanol + carbon dioxide
78
What are the optimum conditions for fermentation?
30-40 °C
Anaerobic conditions
79
Why does fermentation only produce a dilute solution of ethanol?
Yeast dies when concentration is too high
80
What is the use of fractional distillation after fermentation?
Used to concentrate the ethanol solution
81
Describe the process of fractional distillation after fermentation
1. Dilute ethanol is heated using a Bunsen burner
2. Ethanol will boil before the water
3. A Liebig condenser will then condense the ethanol and will produce a concentrated version of the ethanol
82
What is the diameter in nm (size) of atoms and simple molecules?
0.1 - 1 nm
83
What is the diameter in nm (size) of nanoparticles?
1 - 100 nm
84
What do nanoparticles contain?
A few hundred atoms
85
How to calculate surface area to volume ratio?
Surface area to volume ratio = surface area/volume
86
Do nanoparticles have a high or low surface area to volume ratio?
They have a high surface area to volume ratio compared to larger particles - gives them different properties to bulk materials
87
What are the 3 uses of nanoparticles? Why?
1. Catalysts - more surface area means faster rate of reaction
2. Medicines - small particles could be absorbed right into target cells
3. Cosmetics e.g. sunscreen - small particles provide more protection and don’t leave marks on skin & prevent uv rays from reaching skin
88
What are the downsides of using nanoparticles as cosmetics or medicines?
They can have harmful effects on health e.g. nanoparticles could build up in cells over time if they don’t get broken down
89
What are properties of polymers?
Thermal and electrical insulators
Often flexible, can be moulded
Lower density than metals and ceramics
90
What are uses of polymers?
Electrical casing
Carrier bags and squeezy bottles
91
What are the 2 types of ceramics?
1. Clay
2. Glass
92
What is a clay ceramic?
Soft mineral hardened by firing
93
What is an example of a glass ceramic?
Soda lime glass made by heating limestone, sand and sodium carbonate
94
What are properties of ceramics?
Can be moulded and shaped
Strong
Brittle
Glass is transparent
95
What are the uses of clay ceramics?
Bricks
Pottery
96
What are the uses of glass ceramics?
Glassware
97
What are composites?
One material embedded into another
98
What are the properties of composites?
Depends on the material used
E.g. concrete is strong and dense
E.g. carbon fibre is strong and light
99
What is the use of the composite material concrete?
Buildings
100
What is the use of the composite material carbon fibre?
Sports cars
101
What are properties of metals?
Thermal and electrical conductors
Malleable
102
What are the uses of metals?
Wiring
103
What are nanoparticles?
A nanoparticle is a piece of a material consisting of a few hundred atoms, and between 1 nm and 100 nm in size
104
What is a material made of nanoparticles called?
A nanoparticulate
105
Describe how you would carry out a flame test to test for ions
1. Clean a nichrome wire using hydrochloric acid
2. Turn the Bunsen burner onto the blue flame
3. Dip the wire in a solution of the substance being tested
4. Place the wire in the flame and record the colour
106
Why must the wire be cleaned before carrying out a flame test?
To remove any unwanted ions that might obscure the colour of the flame
107
How could you distinguish between two solutions containing aluminium ions and calcium ions?
Add excess sodium hydroxide - both will form white precipitates initially BUT the precipitate formed from aluminium ions will re-dissolve to form a colourless solution
108
What is a flame photometer?
A device used in inorganic analysis - can be used to identify or determine the concentration of metal ions
109
What is the major advantage of flame photometry compared to simple flame testing?
Flame photometry can be used to analyse a mixture of ions whereas flame tests can only be used to identify one ion at a time
110
How do you carry out tests for halide ions?
1. Add a few drops of nitric acid to react with any carbonate ions which might obscure the result
2. Add a couple of drops of silver nitrate
3. Observe the colour of the precipitate
111
What are the 6 cations we need to know tests for?
1. Ammonium
2. Copper (II)
3. Iron (II)
4. Iron (III)
5. Aluminium
6. Calcium
