C6

Question 1

How are unreative metals found in the earth?

Answer 1

Unreative metals are found as the metal itself in the earty

Question 2

How are reactive metals found in the earth?

Answer 2

Reactive metals are found as oxides of the metal in the earth because they have reacted with oxygen

Question 3

What is an ore?

Answer 3

An ore is a rock containing enough metal to make it economically worthwhile extracting the metal from it

Question 4

What is extraction through reduction?

Answer 4

Extraction through reduction is the process in which a more reactive metal takes part in a displacement reaction with the metal oxide to displace it from the ore. In practice we use carbon because it is cheap so it is only used on elements below carbon.

Question 5

Give an example of where extraction through carbon reduction is used in industry

Answer 5

In industry iron is reduced in a blast furnace

Question 6

Complete:

Carbon + iron oxide —>

Answer 6

Carbon + iron oxide —> carbon dioxide + iron

Question 7

What is extraction through electrolysis?

Answer 7

Extraction thorough electrolysis is a method used on metals more reactive than carbon to extract them from their ore. The molten metal oxide is oxidized and reduced to form a gas and metal atoms

Question 8

How would you extract aluminium from aluminium oxide

Answer 8

To extract aluminium you would electrolyse it as it is more reactive than carbon.

1) First you would mix the molten aluminium oxide with cryolite- this lowers its MP and saves money and energy
2) Then turn the power on. The positive aluminium ions will be attracted to the cathode where they are reduced to form aluminium atoms
3) the negative oxygen ions are attracted to the anode where they are oxidised to form oxygen gas

Question 9

Write the half equations for the electrolysis of aluminium oxide

Answer 9

Al^3+ + 3e- —–> Al

2O^2- - 4e- —-> o2

Question 10

Why do we mix cryolite into the molten compound during electrolysis?

Answer 10

Cryolite decreases the substances MP which saves energy and thus money.

Question 11

Why do we have to purify reduced metals using electrolysis

Answer 11

Because reduction produces impure metal we must then purify it using electrolysis

Question 12

Explain how you could purify copper using electrolysis

Answer 12

1) The impure copper is reacted with sulfuric acid to form copper sulfate solution- this is the electrolyte
2) the anode is made out of impure copper
3) the cathode is made out of pure copper
4) when the power is turned on the impure copper atoms at the anode lose two electrons to form copper ions in solution and the anode gets smaller as they leave. The impure atoms in the impure copper simply Falk to the bottom as sludge
5) the positive copper ions in solution are attracted to the negative cathode where they gain two electrons to form copper atoms
6) Thus the cathode gets bigger

Question 13

What is extraction through phytomining?

Answer 13

In phytomining plants which have the ability to take up metals from the soil are planted on low grade metal contaminated soil. The metal ions have no use in the plant so they build up in the leaves. The plants are then harvested, dried and burnt to produce ash containing the metal ions. The metal can then be gained through reduction followed by electrolysis to purify or simply electrolysed.

Question 14

What is extraction through bioleaching?

Answer 14

Bioleaching is the process of using bacteria which live off the energy produced by breaking weak metal sulfate bonds. The bacteria produce a solution called leechate which contains the metal ions. The ions can then be extracted through electrolysis or reduction.

Question 15

What are the advantages and disadvantages of new methods of extraction like phytomining and bioleaching?

Answer 15

They use much less energy and have much less of an impact on the environment but they are slow.

Question 16

What is an alloy?

Answer 16

An alloy is a mixture of a metal and other elements

Question 17

What is steel made from and how does this effect its properties and function?

Answer 17

Steel is made from Iron and Carbon
In high carbon steel it makes it hard a brittle which means it is used in cutting tools such as chisels
In low carbon steel it is softer and more malleable which means it is used in car bodies
Steel is less likely to corrode than iron and stainless steel (Iron + carbon + chromium + nickel) is resistant to corrosion so it is used in cookware.

Question 18

What is bronze made from and how does this effect its properties and function?

Answer 18

Bronze is made from copper and tin. This makes it hard and less corrosive which means it is used for making statues.

Question 19

What is brass made from and how does this effect its properties and function?

Answer 19

Brass is made from copper and zinc which makes it hard but also malleable which means it is used for musical instruments

Question 20

What is solder made from and how does this effect its properties and function?

Answer 20

Solder is made from lead and tin which means unlike pure metals it doesn’t have a definite melting point- it gradually melts/ solidifies. This means it is good for joining components in circuits because it is easily worked. The melting point is also relatively low so it can be meted without deforming the other components

Question 21

What is duralumin made from and how does this effect its properties and function?

Answer 21

Duralumin is made from a mixture of aluminium , copper, magnesium and manganese. This gives it a low density and makes it very strong. This means it is used for aircraft

Question 22

Give the definition of corrosion

Answer 22

Corrosion is the destruction of materials by chemical reactions with substances in the environment

Question 23

What is the corrosion of iron called and how does this process occur and what type of reaction is it?

Answer 23

The corrosion of iron is called rusting it occurs when iron comes into contact with water and oxygen to form hydrated iron (III) oxide. It is a mixture redox reaction.

Question 24

Write the half equation for the corrosion of iron

Answer 24

Fe - 3e- —> Fe^3+

O2 + 2e- —> 2O^2-

Question 25

Explain how barrier methods can prevent corrosion and give examples of when they are used

Answer 25

Barrier methods can prevent corrosion because they proved a physical block to stop the water and oxygen getting to the metal. Examples include paint which is ideal on outdoor structures, oil which is ideal on moving parts and tin plating which is ideal for food cans.

Question 26

Explain how sacrificial protection can prevent corrosion and give examples of when it us used

Answer 26

Sacrificial protection can prevent corrosion because it paces a more reactive metal with the metal you don't want to corrode which more easily loses electrons so reacts with the oxygen and water instead. It is used on ship hulls and underground pipes where magnesium blocks are bolted to the less reactive metal.

Question 27

What is the haber process?

Answer 27

The haber process is a process used to create ammonia which is used in fertilisers

Question 28

What is the equation for the haber process?

Answer 28

The haber process: | N2 + 3H2 ---> 2NH3 (+heat)

Question 29

Where are the materials for the haber process sourced from?

Answer 29

Nitrogen is obtained from the air Hydrogen can be obtained in a number of ways including through reacting methane and steam, hydrocarbons, natural gases or crude oil.

Question 30

What must you do before reacting nitrogen and hydrogen in the haber process?

Answer 30

You must first purify nitrogen and hydrogen before reacting them in the haber process?

Question 31

What temperature is used in the haber process and why?

Answer 31

A temperature of 450 degrees is used in the haber process because a lower temperature favours the forward reactions because it is exothermic so equilibrium will shift to the right to try and create more heat. However a high temperature is needed for a fast reaction rate so 450 degrees is the compromise.

Question 32

What pressure is used in the haber process and why?

Answer 32

A pressure of 200 atm is used in the haber process beach see a higher pressure favours the forward reaction because there are less moles of gas on the right hand side so equilibrium will move in that direction. However high pressures are extremely expensive and dangerous to work in so 200 atm is a compromise

Question 33

What catalyst is used in the haber process and why?

Answer 33

An iron catalyst is used in the haber process because it speeds up the reaction so the temperature doesn't need to be even higher and has no effect on equilibrium.

Question 34

Which three nutrients are essential to a plants growth and life processes?

Answer 34

Nitrogen, potassium and phosphorus are needed for growth and life processes in plants

Question 35

Why do farmers use fertilisers?

Answer 35

Farmers use fertilisers because they contain nutrients which increase crop yield.

Question 36

Name four types of fertilisers and how they are made.

Answer 36

Fertilisers are made by neutralizing an acid and a base Examples of fertilisers include: 1) Ammonium nitrate 2) ammonium phosphate 3) ammonium silicate 4) potassium nitrate

Question 37

What other processes may fertiliser factories carry out besides neutralization to make fertilisers?

Answer 37

Fertilisers factories may carry out processes to make the substances needed like the barber process for ammonia or gaining phosphoric acid from phosphate rocks or the contact process for sulfuric acid

Question 38

What is the contact process used to make?

Answer 38

The contact process is used to make sulfuric acid

Question 39

Explain the process of making sulfuric acid through the contact process

Answer 39

Step 1 sulfur is burned in air to make sulfur dioxide Sulfur + oxygen —> sulfur dioxide S + O2 —> SO2 Step 2 sulfur dioxide is then oxidised with a catalyst to make sulfur trioxide Sulfur dioxide + oxygen —> sulfur trioxide 2SO2 + O2 —> 2SO3 Step 3 sulfur trioxide is dissolved in water to make sulfuric acid

Question 40

What type of reaction is step two of the contact process

Answer 40

Step two of the contact process is a reversible reaction

Question 41

Explain what temperature is needed for step two of the contact process and why

Answer 41

A lower temperature favours the forward reaction because it is exothermic However low temperatures lead to extremely slow reaction rates So a compromise of 450 degrees is used

Question 42

Explain the pressure needed for step two of the contact process and why

Answer 42

A higher pressure favours the forward reaction because there are less moles on the right side However high pressures are expensive and dangerous to work with Therefore a compromise of a pressure just above atmospheric pressure is used

Question 43

Which catalyst in used in step two of the contact process

Answer 43

Vanadium pentoxide catalyst is used in step two of the contact process

Question 44

Explain how to prepare a fertiliser (eg ammonium sulfate) in the lab

Answer 44

1) put the base (ammonia solution) into a conical flask 2) add a few drops of methyl orange to the flask 3) fill the burette with acid (sulfuric acid) and slowly add to the base 4) stop when there is a cooour change and measure the amount of acid needed 5) repeat without the indicator to get a pure sample 6) evaporate some of the solution in a water bath and filtrate to get solid crystals

Question 45

What 5 factors should you consider when creating a product in industrial process to make it economical?

Answer 45

1) cost of raw materials 2) availability of raw materials 3) energy costs 4) rate 5) position of equilibrium

Question 46

What is a life cycle assessment?

Answer 46

A life cycle assessment is a ‘cradle to grave’ analysis of the impact of a manufactured product on the environment

Question 47

Which stages are assessed during a life cycle assessment?

Answer 47

1) Choice of raw materials 2) Manufacture and packaging 3) product use 4) product disposal

Question 48

Name some disadvantages of recycling :

Answer 48

Disadvantages of recycling include: - it isn’t energy free - items need sorting - you can only recycle materials a finite number of times - the recycled material is often lower quality than the original material

Question 49

What is a polymer and why are they useful

Answer 49

A polymer is a molecule made up of a chain of monomer molecules which are useful because they can have a wide range of physical properties depending on which monomers are used

Question 50

Give 3 examples of useful polymers and what they are used to make

Answer 50

- polypropene is a heat resistant insulator used in plastic kettles - low density polythene is flexible and mouldable so is used in plastic bags - High density polyethene is strong and ridged so it is used in water pipes

Question 51

What are ceramics and why are they useful?

Answer 51

Ceramics are made by baking substances and produce brittle stif materials which are useful because they are hard wearing and don’t degrade or corrode.

Question 52

Give two examples of types of ceramics and why they are used for this

Answer 52

- clay is used for bricks because it is hardened by firing which makes it able to withstand the weight of more bricks on top. Clay is also used for pottery because it is soft and malleable when it’s dug up. - glass is a ceramic, borosilicate glass which is a mixture of silica and boron trioxide is used for labware and kitchenware as it has a high MP, soda lime glass which is made from sand, lime stone and sodium carbonate is used for windows and bottles.

Question 53

What is a composite and why are they useful?

Answer 53

A composite is mixture of materials- a reinforcement embedded into a matrix which are useful because their properties can vary depending on the materials used

Question 54

Give two examples of composites and their uses

Answer 54

- Concrete is a composite of aggregate (a mixture of sand and gravel) and cement which gives a a high compressive strength making it ideal for building materials - fibre glass is a composite of fibres of glass and a polymer which gives it a low density but makes it strong so it’s ideal for skis and boats

Question 55

Name some disadvantages of recycling materials

Answer 55

Some disadvantages of recycling include - it isn't energy free - items need sorting - you can only recycle a finite number of times - recycled products are lower quality

Question 56

What is a hydrocarbon?

Answer 56

A hydrocarbon is a molecule made up of only hydrogen and carbon atoms

Question 57

What is an alkane?

Answer 57

An alkane is a saturated hydrocarbon

Question 58

What is the general formula for alkanes?

Answer 58

Alkanes have the general formula | Cn Hn2n+2

Question 59

Name the first four alkanes

Answer 59

1) Methane (CH4) 2) Ethane (C2H6) 3) Propane (C3H8) 4) Butane (C4H10)

Question 60

What do alkanes produce when burned in oxygen?

Answer 60

In excess oxygen alkanes burn to for carbon dioxide and water In limited oxygen alkanes take part in incomplete combustion to form carbon monoxide and water

Question 61

What are alkenes?

Answer 61

Alkenes are unsaturated hydrocarbons with at least one double carbon carbon bond

Question 62

What is the general formula of alkenes?

Answer 62

Alkenes have the general formula | CnH2n

Question 63

Name the first four alkenes

Answer 63

1) Ethene (C2H4) 2) Propene (C3H6) 3) Butene (C4H8) 4) Pentene (C5H10)

Question 64

What is the test for alkenes?

Answer 64

Alkenes turn bromine water colourless

Question 65

In which process to alkenes react with hydrogen?

Answer 65

Alkenes react with hydrogen during hydrogenation

Question 66

What are alcohols?

Answer 66

Alcohols are a homologous series with an OH functional group

Question 67

What is the general formula for alcohols?

Answer 67

The general formula for alcohols is | Cn H2n+1 OH

Question 68

Name the first four alcohols

Answer 68

1) Methanol (CH3OH) 2) Ethanol (C2H5OH) 3) Propanol (C3H7OH) 4) Butanol (C4H9OH)

Question 69

How are carboxylic acids made?

Answer 69

Carboxylic acids are made through oxidising an alcohol

Question 70

What are carboxylic acids?

Answer 70

Carboxylic acids are homologous series with the functional group COOH

Question 71

What is the general formula for carboxylic acids?

Answer 71

The general formula for carboxylic acids is: Cn-1 H2n-1 COOH

Question 72

Name the first four carboxylic acids;

Answer 72

1) Methanoic acid (HCOOH) 2) Ethanoic acid (CH3COOH) 3) Propanoic acid (C2H5COOH) 4) Butanoic acid (C3H7COOH)

Question 73

What is addition polymerisation?

Answer 73

Addition polymerisation is a process in which unsaturated monomers (eg alkenes) open their double bonds to form polymer chains

Question 74

Which conditions are needed for addition polymerisation to take place?

Answer 74

Pressure and a catalyst are needed for addition polymerisation to take place

Question 75

Draw a repeating unit for polyethene

Answer 75

Brackets Lines extended out of brackets n outside brackets

Question 76

What do you need to start addition polymerisation

Answer 76

To start addition polymerisation you need an initiator and you may need to heat the revision mixture in a water bath

Question 77

What is condensation polymerisation?

Answer 77

Condensation polymerisation is the process in which two different types of monomers each with the same functional group at either end of the molecule form bonds which release small molecules (eg water) to create king chains of alternating monomers

Question 78

How can you make a polyester?

Answer 78

To make a polyester a carboxylic acid and an alcohol monomer must undergo condensation polymerisation

Question 79

How do you make a polyamide?

Answer 79

To make a polyamide a carboxylic acid and an amine monomer must undergo condensation polymerisation

Question 80

What is nylon 6,6 and how can you make it in the lab?

Answer 80

Nylon 6,6 is a polyamide which can be made through condensation polymerisation : 1) mix 1,6 diaminohexane and water 2) mix 1,6 hexanedioyl chloride in an organic solvent 3) pour one on top of the other and nylon will form where they meet 4) extract using tweezers and wrap over a rod to form nylon thread

Question 81

Name four types of natural polymers and their monomers

Answer 81

1) DNA monomers A,T,C,G 2) Carbohydrates monomers carbon, oxygen and hydrogen 3) Starch and cellulose monomers sugars 4) Proteins monomers amino acids

Question 82

What is crude oil?

Answer 82

Crude oil is a mixture of hydrocarbons formed over millions of years from the dead remains of plants and animals at high temperature and pressure.

Question 83

Name each of the fractions from top to bottom in a fractionating column during the fractionation of crude oil ((LP) Good people never kill dear old bunnies)

Answer 83

``` LPG Petrol Naphtha Kerosene Diesel Oil Bitumen ```

Question 84

Why do longer hydrocarbon chains have higher boiling points?

Answer 84

Longer hydrocarbon chains have higher boiling points because there are more molecules in the chain so there are more forces between other chains making it harder to break them away from other molecules than smaller chains with less forces. The forces between the atoms inside the chain do not break so the chains remain as chains as gases

Question 85

What is crude oil used for and what is the problem with this?

Answer 85

Crude oil is used for electricity, heating, fuels, chemicals, plastics which means we are very dependant on it. The problem is crude oil is a finite resource which is becoming scarce.

Question 86

What is cracking?

Answer 86

Cracking is a form of thermal decomposition which separates long alkane hydrocarbon chains into smaller alkene and alkane molecules which are in higher demand

Question 87

Explain how cracking is carried out in the lab

Answer 87

Cracking in the lab - vaporised long chain hydrocarbons are passed over powdered aluminium oxide catalyst at 400-700 degrees at 70 atm pressure to form smaller alkane and alkene molecules

Question 88

Give the present composition of the earrings atmosphere

Answer 88

Currently the eat the atmosphere is made up of 78% nitrogen 21% oxygen And less than 1% water vapour, carbon dioxide and methane

Question 89

Explain how scientists predict the earrings atmosphere evolved during the first billion years

Answer 89

Scientists predict the earth was originally molten and there was no atmosphere Eventually it began to cool and a thin crust formed However volcanoes continually erupted releasing mainly carbon dioxide along with steam methane and ammonia Therefore the atmosphere was mainly carbon dioxide and water vapour

Question 90

Explain how scientists predict the earrings atmosphere evolved during the 2nd and 3rd billion years

Answer 90

Scientists predict that the water vapour in the atmosphere condensed into the oceans and the oceans dissolved a lot of the carbon dioxide in the atmosphere. Also nitrogen was starting to form from ammonia reacting with oxygen which is released by dentrifying bacteria into the atmosphere where is builds up because it is unreactive Green plants begin to evolve which remove carbon dioxide from the atmosphere and replace it with oxygen Therefore the atmosphere is a mixture of some carbon dioxide, oxygen and nitrogen

Question 91

Explain how scientists predict the earrings atmosphere evolved in the last billions of years (e.g. from 4 billions years to now)

Answer 91

Scientists predict that the build up of oxygen in the atmosphere from green plants kills off early organisms which aren't adapted to it . It also creates an ozone layer which allows more complex organisms to evolve protected from damaging rays. The carbon dioxide levels drop to practically nothing as they are taken up by plants and locked fossils fuels and rocks

Question 92

What is the greenhouse effect?

Answer 92

The greenhouse effect is the constant absorption and reflection of infra red radiation against the greenhouse gases in the atmosphere which warms earth

Question 93

Explain what happens to the electromagnetic radiation given out by the sun

Answer 93

1) The sun gives out long wavelength graduations mainly visible light but also UV 2) Some of this radiation is reflected back into space when it meets the unearths atmosphere 3) most visible light passes straight through where some of the radiation is absorbed by the earth to warm the planet 4) some of the radiation is reflected back as infra red radiation 5) some infra red radiation passes straight through the atmosphere into space, some is reflected by greenhouse gases and some is absorbed by greenhouse gases

Question 94

What are the enhanced greenhouse effects and what are the problems with this?

Answer 94

The enhanced greenhouse effect occurs when the concentration of greenhouse gases in the atmosphere increases so more great radiation from the earth is absorbed and les emitted back into space which will lead to an increase in global temperature which is called global warming

Question 95

Why are the concentration of greenhouse gases increasing in the atmosphere

Answer 95

The concentration of greenhouse gases in the atmosphere is increasing for a number of reasons including: - increasing population- more human respiration which releases more carbon dioxide - industrialization-increases average energy demands and fossil fuel consumption - deforestation-fields of trees being burnt releases carbon dioxide and trees take in carbon dioxide - agriculture- production of meat and rice produces methane

Question 96

Explain two possible reasons for global warming by scientists

Answer 96

There is a scientific consensus that global warming is anthropogenic due to the extra greenhouse gases produced by greenhouse activity that has lead to an enhanced greenhouse effect Some scientists think there isn’t enough data to prove global warming is anthropogic and argue that the current rises is global temperature are natural fluctuations

Question 97

What is ethanol and what are the pros and cons of using ethanol as an alternative fuel?

Answer 97

Ethanol is a biofuel made from the fermentation of plants Pros: Ethanol is carbon neutral (the carbon released was taking up by the plant while it was growing) and the only other product is water Cons: Engines need to be converted to run on ethanol. There is a worry as ethanol isn’t widely available that when demands increase farmers will switch to producing food crops to make ethanol which will increase food prices

Question 98

What is biodiesel and what are the pros and cons of using biodiesel as an alternative fuel?

Answer 98

Biodiesel is a biofuel produced from vegetable oils Pros- biodiesel is carbon neutral (the carbon dioxide released was taken in by the plant when growing). Engines don’t need to be converted to run on biofuel. The pollutants given off are much les Ethan other fuels Cons- It isn’t or agh all to make enough to replace diesel altogether. It is expensive. It isn’t widely available so there is a worry when demands increase farmers will switch to growing crops needed for biodiesel causing food prices to increase.

Question 99

What is acid rain? How is it formed and what problems does it cause?

Answer 99

Acid rain is a pollutant formed from sulfur dioxide and nitrogen oxide dissolving into clouds to form dilute sulfuric or nitric acid which fall as acid rain Acid rain makes lakes acidic which kills animals, kills trees, corrodes metal and damages statues and buildings

Question 100

What is photochemical smog? How is it formed and what problems does it cause?

Answer 100

Photochemical smog is a pollutant formed from nitrogen oxides from burning fossil fuels reacting with oxygen and sunlight to form ozone (o3). Ozone causes breathing difficulties, headaches and tiredness

Question 101

What is carbon monoxide? How is it formed and what problems does it cause?

Answer 101

Carbon monoxide is a pollutant formed during incomplete combustion such as in car engines. Carbon monoxide leads to a lack of oxygen in the blood which is fatal

Question 102

What is particulate carbon? How is it formed and what problems does it cause?

Answer 102

Particulate carbon is a pollutant formed during incomplete combustion such as in car engines. These small particles float in the air and cause respiratory problems and fall as soot

Question 103

Give two uses of water

Answer 103

Water is used domestically (drinking, washing etc) Water is used industrially (solvents, coolants, cheap raw materials etc)

Question 104

What are the three sources of water

Answer 104

Sources of water - Surface water: lakes, rivers, reservoirs - Groundwater : aquifers - treaters waste water : water contaminated by human processes

Question 105

Explain the process of purifying water

Answer 105

1) Filtration- wire mesh filters our large objects, gravel and sand beds filters out suspended particles 2) Sedimentation- iron sulfate/ aluminium sulfate make fine particles clump together and settle at the bottom 3) chlorination - chlorine gas is bubbles through to kill harmful bacteria and microbes

Question 106

Which three pollutants can potable water contain in small quantities?

Answer 106

Potable water can contain 1) nitrate residue- from fertiliser run off 2) lead compounds- from old lead compounds 3) pesticides residues - from the use of pesticides near water sources

Question 107

What other way can we purify water to make is potable and what are the problem with this?

Answer 107

You can distill sea water to make it potable however this uses high amounts of energy so it is too expensive for producing large amounts

Question 108

Is the reaction between hydrogen and oxygen exothermic or exothermic

Answer 108

The reaction between hydrogen and oxygen is exothermic top produce water and excess energy

Question 109

Explain how a hydrogen oxygen fuel cell works

Answer 109

1) hydrogen and oxygen gas are pumped into the fuel cell containing two electrodes, a potassium hydroxide electrolyte and a catalyst 2) the hydrogen atoms loose electrons at the negative electrode to become hydrogen ions and the oxygen atoms gain electrons to form oxygen ions 3) the ions then react to form water 4) So overall you have a flow of electrons from the negative electrode to the positive then around the circuit which creates electricity