Separate Chemistry 1 Flashcards
(143 cards)
1
Q
Why must a test for a specific ion be unique?
A
Texts are used to identify ions and must be unique so that the test gives an easily observed result which is specific to the ion that is present
2
Q
How would you carry out the flame test to test for ions?
A
Clean a micrometer wire using hydrochloric acid, turn the Bunsen burner onto the blue flame, dip the wire in a solution of the substance being tested and place the wire in the flame and record the colour
3
Q
What is the result of the flame test on lithium ions?
A
Crimson flame
4
Q
What is the result of the flame test on sodium ions?
A
Yellow flame
5
Q
What is the result of the flame test on potassium ions?
A
Lilac flame
6
Q
What is the result of the flame test on calcium ions?
A
Orange-red flame
7
Q
What is the result of the flame test on copper ions?
A
Blue-green flame
8
Q
Why must the wire be cleaned before carrying out a flame test?
A
To remove any unwanted ions that might obscure the colour of the flame
9
Q
Why can a flame test not be used when a compound contains a mixture of metal ions?
A
The flame colours of the ions will blend together so the individual flame colours won’t be seen meaning the ions can’t be identified
10
Q
What is a precipitate?
A
An insoluble solid suspense in a liquid
11
Q
Without using the flame test, how can you test for aqueous metal ions?
A
Add sodium hydroxide solution to the metal ions, observe the colour of the precipitate
12
Q
What colour precipitate forms when sodium hydroxide reacts with calcium ions?
A
White
13
Q
What colour precipitate forms when sodium hydroxide reacts with copper(II) ions?
A
Blue
14
Q
What colour precipitate forms when sodium hydroxide reacts with iron(II) ions?
A
Green
15
Q
What colour precipitate forms when sodium hydroxide reacts with iron(III) ions?
A
Brown
16
Q
What colour precipitate forms when sodium hydroxide reacts with aluminium ions?
A
White
17
Q
What is observed when sodium hydroxide reacts with ammonium ions?
A
A pungent smelling gas is produced which will turn damp red litmus paper blue
18
Q
How could you distinguish between two solution containing aluminium ions and calcium ions?
A
Add excess sodium hydroxide, both will form white precipitates initially, the precipitate formed from aluminium ions will re-dissolve to form a colourless solution
19
Q
How can you test for carbonate ions?
A
Add a few drops of HCI to the sample in a test tube, connect this test tube to a test tube of limewater, if carbonate ions are present, they will react with the acid to produce carbon dioxide which will turn the limewater cloudly when it’s bubbled through limewater
20
Q
How can you test for sulfate ions?
A
Add HCI to remove any CO3 2- ions as these will obscure the results, add a couple of drops a barium chloride and if sulfate ions are present a white precipitate of barium sulfate will form
21
Q
How do you carry out a rest for halide ions?
A
Add a few drops of nitric acid to react with any carbonate ions which might obscure the results, add a couple of drops of silver nitrate and observe the colour of the precipitate
22
Q
What colour precipitate is formed, when silver nitrate is added to a chloride solution?
A
White precipitate of silver chloride
23
Q
What colour precipitate is formed, when silver nitrate is added to a bromide solution?
A
Cream precipitate of silver bromide
24
Q
What colour precipitate is formed, when silver nitrate is added to a iodide solution?
A
Yellow precipitate of silver iodide
25
What is meant by the phrase instrumental methods of analysis?
Methods of analysis that use machinery such as gas chromatography
26
What are the benefits of using instrumental methods for analysis?
Accurate, sensitive and quick to carry out
27
What is a flame photometer?
A device used in inorganic analysis, it can be used to identify or determine the concentration of metal ions
28
How can a flame photometry be used to identify metal ions?
An emission spectrum is produced by the flame photometer, each metal ion produces an unique spectrum so comparing the unknown spectrum to reference spectra can identify the ion
29
How can a flame photometry be used used to determine the concentration of metal ions?
Take reading using a flame photometer of the metal ions at different concentrations, plot a calibration curve and take a reading of the unknown sample and compare to the curve e
30
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
31
What is the general formula for alkanes?
C(n)H(2n+2)
32
What was the name of the first four alkanes?
Methane (CH4), Ethane (C2H6), Propane (C3H8) and Butane (C4H10)
33
What type of bond are formed between carbon and hydrogen atoms in alkanes?
Covalent bonds
34
Why are alkanes saturated hydrocarbons?
All C-C bonds are single bonds and only contain carbon and hydrogen atoms
35
What is the general formula for alkenes?
C(n)H(2n)
36
What are the names of the first four alkenes?
Ethene (C2H4), Propene (C3H6), Butene (C4H8) and Pentene (C5H10)
37
Why are alkenes unsaturated hydrocarbons?
They are compounds made up of only carbon and hydrogen atoms and they contain double carbon bonds
38
What is a functional group?
The group of atoms responsible for the main chemical properties of a compound
39
What functional group do alkenes contain?
C=C double bond
40
What is the difference between but-1-ene and but-2-ene?
But-1-ene and but-2-ene are both alkenes with 4 carbons but the C=C bind is found between different carbons in the chain. In but-1-ene, the double bond is between the first and second carbon whereas in but-2-ene, it’s between the second and third carbon in the chain
41
How can bromine water be used to distinguish between alkanes and alkenes?
When bromine water is added to an alkane, the solution remains orange, when bromine water is added to an alkene,the solution changes from orange to colourless
42
Why do alkenes decolourise bromine water?
Alkenes are unsaturated, the double bond allows alkenes to react with bromine to form a bromoalkane
43
What is produced when a hydrocarbon is completely combusted?
Water and carbon dioxide are produced, carbon and hydrogen are oxidised
44
What is the balanced equation for the combustion of propane?
C3H8 + 5O2 -> 3CO2 + 4H2O
45
What type of reactions happens when energy is released when hydrocarbons undergo complete combustion?
Exothermic reaction
46
What is a polymer?
A substance of high average relative molecular Nass made up of small repeating units
47
How are polymers made?
By linking together lots of small molecules to form a long chain
48
What is the name of the process in which ethene molecules join together to form a polymer?
Addition polymerisation
49
How can ethene molecules undergo polymerisation to form the polymer poly(ethene)?
One of bonds in each C=C double bond breaks and forms a bond with an adjacent monomer, forming a long chain polymer and this requires many ethene monomers
50
What is the name of the product formed from the addition polymerisation of ethene?
Poly(ethene)
51
Can chloroethene undergo addition polymerisation?
Yes because it contains a C=C double bond, the product is poly(chloroethene) or PVC
52
What properties of poly(propene) makes it suitable for making buckets and crates?
Flexible and strong
53
Poly(ethene) is commonly used to make plastic bags, bottles and coatings of electrical wires, why?
Inexpensive, electrical insulator and flexible
54
What is a common use of poly(chloroethene)?
Use for window frame because it’s tough, cheap and long product life
55
What is a common use of poly(tetrafluoroethene) PTFE?
Coating for non-stick pans because it’s tough and non-stick
56
By what process are polyesters formed?
Condensation polymerisation
57
Why are polyesters condensation polymers?
Because a small molecule is released when the bond is formed between two monomers
58
What reactants are required to form an polyester?
Molecules with two carboxylic acid groups and molecules with two alcohol groups
59
What is the formation of an ester bond?
The carboxylic acid loses an OH from the COOH group, the alcohol loses a H from the.-OH group, the two larger molecules combine, forming an ester bond, the zOH- and H+ molecules lost during the bond formation combine to make water
60
What are some of problem associated with polymers?
Crude oil is a finite resource, not biodegradable so take up space in landfill and end up in the oceans, causing problems for marine, produce carbon dioxide if incineration, production process requires a lot of energy and recycling requires careful sorting which is time-consuming
61
What are the advantages associated with recycling polymers?
Provides employment, less crude oil and energy used and reduces the amount of space needed for landfill and fewer polymers end up in the ocean
62
What are the disadvantages associated with recycling polymers?
Labour intensive and expensive, melting polymers produces toxic gases which are harmful for animals and plants, only be recycled a certain number of times before losing their properties and becoming unusable
63
What is starch?
A polymer based on sugars
64
What is DNA?
A polymer made from four different monomers called nucleotides
65
What are proteins?
Polymers based on amino acids
66
What functional group do alcohols contain?
-OH
67
What are the names and formulae of the first four alcohols?
Methanol (CH3OH), Ethanol (C2H5OH), Propanol (C3H7OH) and Butanol (C4H9OH)
68
How is the boiling point affected by an alcohols chain length?
As the chain length of an alcohol increases, boiling point increases
69
Hoe can an alkene be produced from an alcohol?
During a dehydration reaction with sulphuric acid (water is also produced)
70
What functional group do carboxylic acids contain?
-COOH
71
What are the names and formulae of the first four carboxylic acids?
Methanoic acid (HCOOH), Ethanoic acid (CH3COOH), Propanoic acid (C2H5COOH) and Butanoic acid (C3H7COOH)
72
How can ethanol be converted into ethanoic acid?
Oxidation
73
Why do members of the same homologous series undergo similar reactions?
The molecules have the same functional group so have similar chemical properties
74
Which renewable process can be used to produce ethanol?
By fermentation of carbohydrates in aqueous solution with yeast
75
What conditions are required for the fermentation of glucose to form ethanol?
Anaerobic conditions and warm to increase rate of reaction without denaturing enzymes in the yeast
76
What is the word equation for the fermentation of glucose?
Glucose -> ethanol + carbon dioxide
77
How can concentration ethanol be extracted from the fermentation mixture?
Fractional distillation and ethanol has a lower boiling point than water so will evaporate first
78
Compare the size of nano particles to atoms and molecules
Nanoparticles contain a few hundred atoms and are between 1-100 nm across
79
What are some of the risks associated with nanoparticulate materials?
Little is known about the effects of nanoparticles, may be harmful to health, may catalyse harmful reactions inside the body and large surface surface area to volume ration may allow toxic substances to bind to them and enter the body
80
Why would nanoparticles be useful catalyst?
Nanoparticles have a very high surface area to volume ratio
81
What is the equation to calculate the surface area to volume ratio?
Surface area / volume
82
Why might nanotubes be used to make electrical circuits for computers?
Can conduct electricity, are very small so take up little space and lightweight
83
Why might nanoparticles be used in sunscreen?
Some nanoparticles block UV light, nano particles don’t leave white marks on skin
84
What are the general properties of glass ceramics?
Transparent, strong but brittle, easily moulded into shapes and poor conductors
85
What are the general properties of clay ceramics?
Opaque, soft and malleable, hardened with heat, briitle once hardened and poor conductors
86
What are the general properties of polymers?
Properties can be adapted to suit the purpose, usually thought and flexible, can be transparent or opaque and poor conductors
87
What are the general properties of metals?
Shiny, malleable, ductile, good conductors, and can form alloys to produce more desirable properties
88
What is a composite material?
Contains two or more materials with different properties, there are two components: the reinforcement and the matrix
89
Why do composite materials have a wide range of different properties?
As composite materials are made of several materials, the properties can be tailored to suit the need of the composite, different composite materials contain different reinforcement and matrixes so the properties vary
90
What should be used used to construct large buildings?
Reinforced concrete because it’s strong in compression and tension and slightly flexible
91
What should be used to make tennis rackets?
Fibre reinforced plastic because it has a low density so is lightweight and is flexible and strong in tension
92
What are the typical properties of transition metals?
High melting point and density, form coloured compounds and can be used as catalyst
93
Which transition metal is used as a catalyst in the Haber process?
Iron
94
What causes metals to corrode?
Oxygen reacts with the metal to form a metal oxide
95
Why is corrosion of a metal a redox reaction?
The metal loses electrons and oxygen gains electrons
96
What is rusting?
Rusting is the name specifically given to the corrosion of iron when it reacts to oxygen and water in the air
97
What two substances need to be excluded to prevent rusting?
Oxygen and water
98
How can oxygen and water be excluded to prevent iron rusting?
Paint the metal, coat the metal in oil/grease, cover the metal in plastic and keep the metal in a vacuum container
99
What is sacrificial protection?
Sacrificial protection is when the metal being protected from rusting is galvanised with a more reactive metal and the outer metal will corrode first and will prevent the corrosion of the inner metal
100
Which metal is used to in the sacrificial protection of iron?
Zinc
101
What is electroplating?
A process in which a metal is coated with a layer of another metal
102
What are two reasons for using electroplating?
To make a metal more resistant to corrosion and to improve the appearance of a metal
103
How does the process of electroplating works?
The metal being coated is the Cathie, the metal that will form the exterior layer is the anode, the electrolyte solution must contain ions of the metal which will form the outer coating, a power supply is connected to both electrodes
104
Why are pure metals generally very malleable?
The atoms lie in uniform rows which are able to slide over one another
105
How does a pure metal that can be converted into an alloy increase the strength of the product?
Alloys contain several metals which will have different sized atoms, this distorts the regular array of the atoms so the layers are unable to slide over one another very easily
106
Why is iron alloyed with other metals to produce alloy steels?
it’s relatively brittle so it’s combined with other elements to produce a material with more desirable qualities
107
What property of copper makes it suitable to be used in electrical cables?
Very good electrical conductor
108
What property of aluminium makes it suitable for use in aircrafts?
Low density
109
What is key property of gold that makes it suitable for use in jewellery?
Very unreactive so resist to corrosion
110
What is magnalium?
alloy of magnesium and aluminium, it’s lighter and stronger than aluminium and more resistant to corrosion and it’s used car and aircrafts
111
What is brass?
Alloy of copper and zinc, it’s hard and resistant to corrosion and it’s used for decorative hardware
112
How do you calculate the concentration of a solution of mol dm-3?
Concentration = moles / volume
113
How do you convert concentration in g dm-3 to mol dm-3?
Concentration (mol dm-3) = concentration (g dm-3) / molecular mass
114
How to carry out an acid-alkali titration to find the concentration of alkali?
Rinse the pipettes with the solution of unknown concentrations, use this pipettes to add a known volume of alkali to a conical flask, add a few drops of indicator, rinse and fill the bursts with acid, gradually add the acid to the conical flask, record the volume in the burette when the indicator changes colour, repeat the experiment until you have concordant result and use results to calculate a mean titre and the concentration of alkali
115
How could you calculate the concentration of the acid, given the alkali concentration and volume?
Calculate the number of moles of alkali using the known volume and concentration, uses the chemical equation to work out the ration of acid and alkali that react and hence work out how many mole of acid have reacted and then divide the moles of acid by the volume used in neutralisation to find concentration
116
What is theoretical yield?
The amount of product that would be collected under perfect reaction conditions
117
How do you calculate percentage yield?
(Actual yield / theoretical yield) x 100
118
Why could the actual yield of product be less than expected?
Incomplete reaction, competing, unwanted side reactions and practical losses
119
What is the atom economy of a reaction?
Atom economy is a measure of the efficiency of the reaction, it looks at the amount of reactants that get turned into useful product
120
How can atom economy be calculated?
(Molecular mass of desired product / molecular mass of reactants) x 100
121
Why might one reaction pathway be chosen over another?
Higher atom economy, higher yield, faster rate, less harmful and more useful
122
What does Avogadros law state about gas volumes?
At the same temperature and pressure equals amounts of gas will occupy the same volume
123
What is the molar volume of a gas?
The volume occupied by one mole of molecules of any gas at room temperature and pressure
124
What is RTP?
Room temperature and pressure
125
How can the molar volume of a gas be calculated?
Molar volume = volume / moles of gas
126
What factors should be considered before deciding the conditions for an industrial reaction?
Availability and cost of raw materials, energy requirements, optimum temperature and pressure for high yield and fast of reaction and need for a catalyst
127
What is the purpose of fertilisers?
To promote plant growth
128
What chemical compounds might fertilisers contain?
Nitrogen, phosphorus and potassium compounds
129
What compound are found in NPK fertilisers?
A combination of all three fertiliser compounds
130
Which part of plant growth do the compounds nitrogen, potassium and phosphorus help with?
Nitrogen: healthy leaves, Phosphorus: healthy roots and potassium: growth and healthy fruit/flowers
131
Which ammonium salt is most commonly used in fertilisers?
Ammonium nitrate
132
How is the salt ammonium nitrate formed?
React ammonia with nitric acid
133
What is the chemical equation for the formation of ammonium sulfate from ammonia and sulfuric acid?
2NH3 + H2SO4 -> (NH4)2SO4
134
How can ammonium sulfate be prepared in a laboratory?
Titration, exact volume of ammonium added to a conical flask using a pipettes, add a few drops of indicator, add sulfate from the burette drop by drop, stop when the indicator changes colour, repeat adding the exact volumes of reactants without the indicator and remove the water by evaporation and crystallisation leaving pure crystals
135
How can ammonium sulfate be produced on an industrial scale?
Raw materials obtained from the Haber process and the contact process, a large large reactor chamber is filled with ammonia gas, sulfuric acid is sprayed into the chamber from above and ammunium sulfate crystals are produced
136
How is a voltage produced from a chemical cell?
Two metals of different reactivities are placed in an electrolytes, the more reactive metal releases electrons, becoming positively charged, the electrons flow to the other electrode with become negatively charged, the difference in the ability of each electrode to release electrons causes a voltage to be produced
137
When will a chemical cell stop producing a voltage?
When one of the reactants has been used up
138
What is a fuel cell?
A cell that continually produces a voltage as long as it’s supplied with oxygen and a fuel
139
What is the only product of a hydrogen-oxygen fuel cell?
Water
140
How does a hydrogen-oxygen fuel cell work?
Hydrogen and oxygen are pumped through porous electrodes, the electrolyte is often an acid and hydrogen and oxygen react, producing electricity and water
141
What are the advantages of using fuel cells?
No pollution production, produce more energy than an alternative fuel and continuous process as long as fuel is supplied
142
What are the disadvantages of using fuel cells?
Materials used to make them are expensive, high pressure tanks required to store oxygen and fuels, hydrogen is expensive and hard to store and efficiency is affected by temperature
143
What is the equation for the overall reaction that takes place in a hydrogen-oxygen fuel cell?
2H2 + O2 -> 2H2O
