Difficult Topics Paper 1 Flashcards
(140 cards)
1
Q
What is the method for creating an insoluble salt?
A
PRECIPITATION REACTION:
Mixing two soluble salts together produces an insoluble salt
METHOD: (Using the reaction of lead nitrate and sodium chloride to produce lead chloride which is insoluble)
- In a test tube add one spatula of lead nitrate and add deionised water to dissolve it, to make sure there are no ions about, mix thoroughly
-Repeat the same process with sodium chloride, shake thoroughly to ensure that it has been dissolved
- Poor the contents of the two test tubes into a beaker, and mix together. The insoluble salt (Lead Chloride) should precipitate out
- Put filter paper and a filter funnel on top of a conical flask and poor the contents of the beaker into the flask, ensure that all of the precipitate has been passed through the filter paper by mixing what’s left in the beaker with deionised water and pouring back into the conical flask
- The lead chloride will be on top of the filter paper, remove the filter paper from the flask and leave it in an oven to dry, creating an insoluble salt.
2
Q
What are the two methods to create a soluble salt?
A
- Using an acid and an insoluble base
- Acid Alkali titration reaction
3
Q
How do you produce a soluble salt by using an acid and an insoluble base?
A
- Heat the acid in a water bath, to this in a fume cupboard to ensure that no harmful fumes escape
- Poor the insoluble base into the beaker containing the acid and mix, add excess of the insoluble base. It will be clear when all the acid has been neutralised because all of the excess solid will sink to the bottom
-Filter off the excess solid using filter paper and a funnel, in a conical flask
- Heat the solution gently using a Bunsen burner, to evaporate off some of the water
- Leave the solution to cool and allow the salt to crystallise
EXAMPLE: Adding copper oxide to warm sulfuric acid to make copper sulfate
4
Q
How will equilibrium be affected if temperature is increased?
A
The equilibirum will move in the endothermic direction to absorb the extra heat
5
Q
How will equilibrium be affected if temperature is decreased?
A
The equilibirum will move in the exothermic direction to release the extra heat
6
Q
How will equilibrium be affected if pressure is decreased?
A
The equilibirum will move towards the side that has more molecules of gas to increase pressure
7
Q
How will equilibrium be affected if pressure is increased?
A
The equilibirum will move towards the side that has fewer molecules of gas to reduce pressure
8
Q
How will equilibrium be affected if concentration of the reactants is increased?
A
The equilibirum will move to the right to use up the reactants (making more products)
9
Q
How will equilibrium be affected if concentration of the products is increased?
A
The equilibrium will move to the left to use up the products (making more reactants)
10
Q
How will equilibrium be affected if concentration of the reactants is decreased?
A
The equilibirum will move to the left to use up the products (making less products)
11
Q
How will equilibrium be affected if concentration of the products is decreased?
A
The equilibirum will move to the left to use up the reactants (making less reactants)
12
Q
Nitrates
A
Soluble
13
Q
Common Chlorides
A
Soluble (Except Silver and lead)
14
Q
Common Sulfates
A
Soluble (Except Lead, Barium and calcium sulfate)
15
Q
Carbonates and hydroxides
A
Insoluble (except for sodium, potassium and ammonium)
16
Q
Silver Nitrate
A
Soluble
17
Q
Lead Sulfate
A
Insoluble
18
Q
Lead Carbonate
A
Insoluble
19
Q
Sodium Hydroxide
A
Soluble
20
Q
Barium Hydroxide
A
Insoluble
21
Q
Sodium chloride
A
Soluble
22
Q
Lead Chloride
A
Insoluble
23
Q
How do you make a soluble salt using an acid/alkali titration?
A
-Measure out a set volume of acid into a conical flask using a pipette. Add a few drops of indicator
-Slowly add alkali to the acid, using a burette, until you reach the end point- this is where the acid’s been exactly neutralised and the indicator changes colour
- Then carry out the reaction using exactly the same volumes of acid but with no indicator, so the salt won’t be contaminated with indicator
- The solution that remains when the reaction is complete contains only the salt and the water
- Slowly evaporate off some of the water and then leave the solution to crystallise
- Filter off the solid and dry it- leaving a pure dry soluble salt
24
Q
What is the mobile phase?
A
Where the molecules can move - e.g. solvent
25
What is the stationary phase?
Where the molecules cannot move - e.g. chromatography paper
26
What is the seperation technique for a Mixture of insoluble solid and liquid
Filtration
27
What is the seperation technique for a Mixture of soluble solid and liquid (solution)
Crystallisation
28
What is the seperation technique for a Mixture of liquids
Fractional Distillation, Simple distillation
29
What is the seperation technique for a mixture of dissolved solids
Chromatography
30
What is the process of simple distillation?
Separating a liquid from a solution (e.g. water from the sea)
APPARATUS
- Set up the apparatus with a distillation flask with a bung on top and a thermometer poking through the bung, a condenser and a flask
METHOD
- Pour solution into the distillation flask
- Connect the bottom end of the condenser to a cold tap using rubber tubing. Run cold water through the condenser to keep it cool
- Gradually heat the distillation flask. The part of the solution that has the lowest boiling point will evaporate- in this case it's water
- The water vapour passes into the condenser where it cools and condenses. It then flows into the beaker where it is collected
- Eventually just salt will be left in the flask
31
What is the process of fractional distillation?
Separating a mixture of liquids with different boiling points
APPARATUS
- Bunsen burner
- distillation flask
-Fractionating column
- Condenser
- Bung attached to top of fractionating column
- Thermometer, through the bung
- Test Tubes
METHOD:
-Put mixture in a flask
- Gradually heat the flask. The different liquids will all have different boiling points- so they evaporate at different temperatures
- The liquid with the lowest boiling point evaporates first . When the temperature on the thermometer matches the boiling point of this liquid. It will reach the top of the column.
- Liquids with higher boiling points might start to evaporate. But the column is cooler towards the top, so they will only get part of the way up before condensing and running back down the flask
- When the first liquid has been collected, raise the temperature until the next one reaches the top
32
What is the process of crystallisation
- Used to seperate a mixture of soluble solid and liquid (solution)
METHOD
- Pour the solution into an evaporating dish and gently heat the solution. Some of the water will evaporate and the solution will get more concentrated#
- Once some of the water has evaporated, or when you see crystals start to form, remove the dish from the heat and leave the solution to cool
- The salt should start to form crystals as it becomes insoluble in the col, highly concentrated solution
- Filter the crystals out of the solution, and leave them in a warm place to dry. You could use an oven
33
What is the process of chromatography?
Draw a line near the bottom of the paper — this is the baseline.
Put some of the solvent into a beaker. Dip the bottom of the paper (but not the spot) into the solvent.
Put a watch glass on the top of the beaker to stop any solvent from evaporating away.
The solvent will start to move up the paper. When the chemicals in the mixture dissolve in the solvent, they will move up the paper too.
You will see the different chemicals in the sample separate out, forming spots at different places on the paper.
Remove the paper from the beaker before the solvent reaches the top.
Mark the distance the solvent has moved (the solvent front) in pencil.
34
What are the water treatment processes in the uk?
Filtration - removes large impurities
Sedimentation - removes any small impurities
Chlorination - kills any harmful bacteria and microbes
35
What is surface water?
From lakes, rivers and reservoirs. In much of England and Wales, these sources start to run dry during the summer months.
36
What is ground water?
from aquifers (rocks that trap water underground).
In parts of south-east England, where surface water is very limited. as much as 70% of the domestic water supply comes from ground water
37
What is waste water?
from water that's been contaminated by a human process, e-g. as a by-product from some industrial processes. Treating waste water to make it potable is preferable to disposing of the water, which can be polluting-How easy waste water is to treat depends on the levels of contaminants in it.
38
Why is distillation not used to produce potable water in the UK?
It's too expensive when producing large quantities of water
39
Why is deionised water used in chemical experiments?
Deionised water is water that has had the ions (such as calcium, iron and copper ions) that are present in normal tap water removed. These ions, although present in small amounts and harmless in tap water, can interfere with reactions. Using normal water could give your experiment a false result.
40
What is the test for purity?
By comparing the actual melting point of the sample to the expected value.
Impure substances will melt over a variety of temperatures
41
What is an acid?
A substance that produces H+ ions
42
What is a base?
A substance that neutralises an acid
43
What is an alkali?
A substance that produces OH- ions
44
What is a strong acid?
An acid that almost completely ionises in water
45
What is a weak acid?
An acid that does not fully ionise in water
46
What is a concentrated acid?
An acid that has a large number of acid molecules compared to water
47
What is a dilute acid?
An acid that has a low number of acid molecules compared to water
48
What happens if you increase the H+ concentration by a factor of 10?
The pH decreases by 1
49
What happens if you decrease the H+ concentration by a factor of 10?
The pH increases by 1
50
What is the reaction between a metal and an acid?
Acid + Metal —-> Salt + Hydrogen
51
What is the reaction between a metal oxide and an acid?
Acid + Metal Oxide —> Salt + Water
52
What is the reaction between a metal carbonate and an acid?
Acid + Metal Carbonate —> Salt + Water + Carbon dioxide
53
What is the test for hydrogen?
Take a lighted splint
which makes a “squeaky pop” sound
54
What is the test for carbon dioxide?
Bubble through limewater. If present, it turns cloudy
55
How do you make an insoluble salt?
Precipitation reaction (two soluble salts)
56
What is an electrolyte?
A molten or dissolved ionic compound that can conduct electricity
57
What happens during electrolysis?
The cations move towards the cathode and become reduced
The anions move towards the anode and become oxidised
58
Why can an ionic compound not conduct electricity?
The ions are in fixed positions and cannot move
59
What happens at the cathode in the electrolysis of aqueous solutions?
If the metal is more reactive than hydrogen, hydrogen is produced
60
What happens at the anode in the electrolysis of aqueous solutions?
If none of the halide ions (chlorine, bromine and iodine) are present, oxygen is formed
61
What is the half equation if oxygen is produced at the anode in electrolysis of an aqueous solution?
4OH- —-> O2 + 2H2o + 4e-
62
What is the product at cathode and anode of the electrolysis of aqueous copper chloride?
Cathode: Copper
Anode: Chlorine
63
What are the half equations at cathode and anode of the electrolysis of aqueous copper chloride?
Cathode: Cu2+ + 2e- --> Cu
Anode: 2Cl- --> Cl2 + 2e-
64
What is the product at anode and cathode of the electrolysis of aqueous Sodium sulfate
Cathode: Hydrogen
Anode: Oxygen
65
What are the half equations at anode and cathode of the electrolysis of aqueous Sodium sulfate
Cathode: 2H+ + 2e- --> H2
Anode: 4OH- ---> O2 + 2H2O + 4e-
66
What is the product at the anode and cathode of the electrolysis of potassium chloride?
Cathode: Potassium
Anode: Chlorine
67
What are the half equations at the anode and cathode of the electrolysis of potassium chloride?
Cathode: K+ +e- --> K
Anode: 2Cl- --> Cl2 + 2E-
68
What happens during the electrolysis of copper sulfate with non-inert electrodes?
- The mass of the anode will decrease and the mass of the cathode will increase. This is because copper is transferred from the anode to the cathode
69
What happens during the electrolysis of copper sulfate with inert electrodes?
Copper metal is produced at the cathode
Oxygen and water are produced at the anode
70
What did JJ Thomson conclude about the structure of an atom?
Atoms were small spheres containing electrons in a ‘plum pudding model’
71
What did Ernest Rutherford do?
He fired positive alpha particles at an extremely thin gold sheet. Some were slightly deflected and very little were deflected straight back. The nuclear model was then created
72
What did Niels Bohr do?
He proposed a new model where electrons orbited the nucleus in shells
73
What is the relative atomic mass?
The average mass of one atom of the element compared to 1/12 of the mass of one atom of carbon-12
74
How did Mendeleev order the first periodic table?
By order of atomic mass
75
What is an ion?
Charged particles
76
What is ionic bonding?
When a metal and a non-metal react together to form a strong compound held together by electrostatic forces
77
What is covalent bonding?
A bond that forms when a pair of electrons is shared between two atoms
78
What are the properties of buckminsterfullerene?
Can be used as industrial catalysts
High surface area
Fullerenes can be used to cage other molecules- can be used to deliver a drug
79
What is metallic bonding?
The electrostatic force between metal ion
80
What are the properties of metals?
High melting and boiling points
High density
Malleable
Good conductors of heat and electricity
81
What are the properties of an ionic compound?
- Always have giant lattice structures
- High melting and boiling points
- Don't conduct electricity because the ions are fixed in place , can conduct when melted
- Dissolve easily in waER
82
What are the properties of a covalent bond?
- Simple molecular structures
- Atoms within molecules are held together by strong covalent bonds, however the forces of attraction between molecules are very weak
- Melting and boiling points are very low
- Gases or liquids at room temperature
- Don't conduct electricity because they are not free to move
83
How does bioleaching work?
Uses bacteria to separate metals from their ores. The bacteria get energy from the bonds between the atoms in the ore, separating out the metal from the ore in the process.
84
How does phytoextraction work?
Involves growing plants in soil that contain metal compounds. The plants can't get rid of or use the metals so they gradually build up in the leaves. The plants can be harvested, dried and burned in a furnace. The ash contains metal compounds from which the metal can be extracted using electrolysis.
85
What are the 4 things to consider when it comes to a LSA?
Choice of material
Manufacture
Product use
Disposal
86
What are the properties of transition metals?
hard
Strong
Shiny
Malleable
Conduct heat and electricity
High melting points
High densities
87
Why is the transition metal copper used for water pipes?
Copper is used for water pipes beacuse it is malleable and corrosion resistant
88
What catalyst is used in the Haber process?
Iron
89
What is the definition of corrosion
When metals are broken down by reacting with substances in their environment
90
What is the word equation for the corrosion of iron
Iron + water + oxygen ---> hydrated iron (III) oxide
91
Why doesn't aluminium corrode like iron?
The aluminium oxide forms a protective layer, preventing further oxidation
92
What is a barrier method to prevent corrosion?
Coat the iron in something to prevent the oxygen and water from touching the iron
93
Give three examples of barrier methods to prevent the corrosion of iron
- Painting (works for large pieces of iron like ships)
- Electroplating (using electrolysis to cover the metal in another metal)
- Oiling or greasing (works when the object has moving parts, like a bike chain)
94
How does a sacrificial method work for preventing corrosion?
Adding a more reactive metal to the iron, so that metal reacts with oxygen instead
95
How does galvanisation work?
Prevents iron from rusting
- Coating the iron in a thin layer of zinc
- Zinc acs as a physical barrier to prevent water or oxygen from reaching the iron
- If the zinc gets scratched, the zinc will react with any nearby oxygen, as zinc is more reactive than iron
96
What is the balanced symbol equation for the haber process?
N2 + 3H2 <=> 2NH3
97
Describe the haber process
The haber process is an exothermic reaction which involves the reaction of nitrogen which is obtained from the air ,hydrogen which is made from hydrocarbons and an iron catalyst
The haber process is the industrial production of ammonia which is used for fertilisers
The haber process is a reversible reaction, so some of the ammonia formed will break back down to form hydrogen and nitrogen
98
How does the industiral process of the haber process work
Step 1: Hydrogen and nitrogen are fed into the top of the machine, where they can mix together
Step 2: The hydrogen and nitrogen reach the reaction vessel, where the conditions are kept at 450 degrees Celsius and 200 atmospheres, the gasses are free to pass over the iron catalyst in the reaction vessel.
Step 3: Some of nitrogen and hydrogen will react to form ammonia, however because it is a reversible reaction, some of this ammonia will revert back to nitrogen and hydrogen
Step 4: The ammonia is separated from the gaseous nitrogen and hydrogen, by being passed through a cool condenser and condenses to form a liquid.
Step 5: The gaseous nitrogen and hydrogen have lower boiling points so they are not able to condense to form liquids and are recycled back around to the reaction mixture
99
What are the reaction conditions for the haber process?
450 degrees celcius
200 atmospheres
100
Explain why a temperature of 450°C is used in the Haber process.
450°C is a compromise between percentage yield, rate of reaction, and cost.
The forward reaction is exothermic, and so the reaction should be done at a low temperature to get a high yield.
The reaction will be faster at higher temperatures because the particles will have more energy, and so will be more likely to collide with enough energy to react.
Generating high temperatures is expensive, so we can't use a very high temperature.
101
Explain why a pressure of 200 atmospheres is used in the Haber process.
200 atm is a compromise between percentage yield, rate of reaction, and cost.
There are fewer molecules of product than reactant, so a higher pressure will result in a larger yield
The reaction will be faster at higher pressures because the particles will have more energy and so will be more likely to collide and react.
Generating high pressures is expensive, so we can't use a very high pressure
102
What is a fertiliser?
A substance that is applied to the soil, in order to supply plants with nutrients
103
What is a formulation?
A formulation is a mixture made from a specific ratio of chemicals
To ensure that the product has the required properties
104
What are the three main elements that plants need from the soil and are used in fertilisers
Nitrogen, Phosphorus, Potassium
105
Why is nitrogen important for plants?
it is required to make amino acids and hence proteins, which are essential for growth.
106
What is the main source of nitrogen?
Ammonia, which is made in the Haber process
107
How can ammonia produce nitric acid
Ammonia can react with oxygen and water in a series of reactions to make nitric acid.
108
How can ammonia produce ammonium salts
Ammonia can react with acid (nitric acid) to form ammonium salts
109
How is phosphate produced?
It is mined from the ground as phosphate rock
110
Why can't plants use phosphate salts as nutrients?
the phosphate salts in the rock are insoluble, so they can't be used directly in fertilisers
111
How are phosphate rocks made into nutrients that the plant can use
By reacting the phosphate rocks with acids to produce soluble salts
112
What useful compound is produced when phosphate rock is reacted with phosphoric acid?
Triple superphosphate
113
How is potassium produced for fertilisers?
Potassium chloride and potassium sulphate can be both be mined from the ground and then used directly in fertilisers.
114
what is the equation for calculating molar volume?
Molar volume (dm3 mol-1) = gas volume (dm3) /number of moles
115
What is the equation for calculating number of moles from the volume of a gas?
moles= volume (dm3) / 24
116
What is avogadro's law?
Under the same conditions, the same number of moles of different gases all occupy the same volume
117
At room temperature what is the molar volume of all gases?
24 dm3
118
What is the definition of molar volume?
The volume occupied by one mole of gas
119
How do you convert from dm3 to cm3?
multiply by 1000 (e.g. 24dm3 = 24000 cm3)
120
What is a fuel cell?
A cell that converts chemical energy in a fuel and oxygen into electricity
121
Which direction do the electrons flow in a hydrogen-oxygen fuel cell?
From the anode to the cathode
122
What happens at the anode in a hydrogen- oxygen fuel cell ?
Hydrogen comes in from the left and is oxidised by the anode
123
What is the half equation at the anode in a hydrogen oxygen fuel cell?
H2--> 2H+ + 2e-
124
What is the half equation at the cathode in a hydrogen-oxygen fuel cell
O2 + 4H+ + 4e- ---> 2H2O
125
What is the overall equation in a hydrogen- oxygen fuel cell?
O2 +2H2 ----> 2H2O
126
How do fuel cells work?
As fuel enters the cell, it become oxidised. This sets up a potential difference across the cell
127
What are the main advantages of hydrogen-oxygen fuel cells?
Fuel cells last longer than batteries
The reaction doesn't produce any pollutants
Hydrogen and oxygen are both renewable
128
What are the main disadvantages of hydrogen-oxygen fuel cells?
Hydrogen is highly flammable, so it is dangerous to store
It requires energy to produce hydrogen
Hydrogen gas requires a large space to store
129
What is the purpose of a titration?
Titrations allow you to find out exactly how much of an acid is needed to neutralise a given quantity of alkali
130
What is the equation for the concentration?
Concentration (mol dm3) = number of moles/volume (dm3)
131
What is the equation for atom economy?
atom economy = total mR of desired products/ total mR of all products x 100
132
Why are alloys used?
Some metals aren't strong enough for some uses as they are malleable, so alloys are used instead
133
How are allows used?
alloys are made by adding another element to a metal
134
Why are alloys strong?
Different elements have different sized atoms. The smaller atoms will upset the larger atoms, making it more difficult for them to slide over each other. So alloys are stronger
135
What are some uses of alloys?
Bronze ( Copper + tin) is used to make medals
Brass (copper + zinc) is used in water taps
Alluminium alloys are used for aircraft
136
What are the properties of graphite?
Soft and slippery
High melting and boiling points
Insoluble
Does conduct electricity
137
What are the properties of diamond?
- Very hard
- High melting and boiling points
- Insoluble
- Doesn't conduct electricity
138
What are uses for diamond
Strengthening cutting tools
139
What are uses for graphite?
Lubrication
140
Describe the structure of graphene
Graphene is a type of fullerene, it is one layer of graphite
- It's a sheet of carbon atoms joined together in hexagons
- The sheet is just one atoms thick, making it a two dimensional substance
