TOPIC 10 - USING RESOURCES

Question 1

What are ceramics?

Answer 1

Non-metals solids with high melting points that are not made from carbon-based compounds.

Question 2

Explain ceramics that are made from clay?

Answer 2

Clay is a soft material when dug up, so it can be moulded into different shapes. When it is fired at high temperatures, it hardens to form ceramic. Its ability to be moulded when wet and then hardened makes clay ideal for making pottery and bricks.

Question 3

Explain glass as a ceramic?

Answer 3

Glass is generally transparent, can be moulded when hot and can be brittle when thin.
Most glass made is soda-lime glass, which is made by heating a mixture of limestone, sand and sodium carbonate until it melts. When the mixture cools it comes out as glass.

Borosilicate glass has a higher melting point than soda-lime glass. It is made in the same way as soda-lime glass, using a mixture of sand and boron trioxide.

Question 4

What are composites?

Answer 4

Composites are made of one material embedded in another. Fibres and fragments of a material (known as reinforcements) are surrounded by a matrix acting as a binder. The properties of a composite depend on the properties of the materials it is made from.

Question 5

What are fibreglass?

Answer 5

Fibreglass consists of fibres of glass embedded in a matrix made of polymer (plastic). It has a low density (like plastic) but it is very strong (like glass). It is used for things like skis, boats and surfboards.

Question 6

What is carbon fibre?

Answer 6

Carbon fibre composites also have a polymer matrix. The reinforcements is either made from long chains of carbon atoms bonded together (carbon fibres) or from carbon nanotubes. These composites are very strong and light so are used in aerospace and sports car manufacturing.

Question 7

What is concrete?

Answer 7

Made from aggregrate (a mixture of sand and gravel) embedded in cement. It is very strong. This makes it ideal for use as a building material e.g. in skate parks.

Question 8

What is wood?

Answer 8

A natural composite of cellulose fibres held together by an organic polymer matrix.

Question 9

What are low density polymers?

Answer 9

Low density poly(ethene) is made from ethene at a moderate temperature under high pressure and with a catalyst. It is flexible and used for bags and bottles.

Question 10

What are high density polymers?

Answer 10

High density poly(ethene) is also made from ethene but at a lower temperature and pressure with with a different catalyst. It is more rigid and is used for water tanks and drainpipes.

Question 11

What are thermosoftening polymers?

Answer 11

Contain individual polymer chains entwined together with weak forces between the chains. You can melt these plastics and remould them.

Question 12

What is thermosetting polymers?

Answer 12

Contain monomers that can form cross-links between the polymer chains, holding the chains together in a solid structure. Unlike thermosoftening polymers, these polymers do not soften when heated. They are strong, hard and rigid.

Question 13

What are the properties of ceramics?

Answer 13

Insulators of heat and electricity.
Brittle (they aren’y very flexible and break easily)
Stiff.

Question 14

What are the properties of polymers?

Answer 14

Insulators of heat and electricty.
They can be flexible
Easy moulded.
Many applications including in clothing, insulators and in electrical items.

Question 15

What are the properties of composites?

Answer 15

Depend on the matrix/binder and the reinforcement used to make them so they have many different uses.

Question 16

What are the properties of metals?

Answer 16

Malleable, good conductors of heat and electricity, ductile (they can be drawn into wires), shiny and stiff. Metals have many uses including in electrical wires, car body-work, and cutlery.

Question 17

What are alloys?

Answer 17

Made by adding another element to the metal. This disrupts the structure of the metal, making it harder than pure metals.

Question 18

Give examples of some alloys?

Answer 18

Bronze = copper and tin
Brass = copper and zinc
Gold alloys are used to make jewllery.
Alluminium alloys are used to make aircraft.

Question 19

What is corrosion?

Answer 19

Where metals react with substances in their environment and are gradually destroyed. Iron corrodes easily, it rusts.
Corrosion only happens on the surface of a material where it is exposed to air.

Question 20

What does iron need ti rust?

Answer 20

Iron needs contact with both oxygen and water.

Question 21

What is the formula for rust?

Answer 21

iron + oxygen + water = hydrated iron (III) oxide.

Question 22

Why will all the iron in an object eventually corode away?

Answer 22

Rust is a soft and crumbly solid which flakes off to leave more iron available to rust again. This means that, eventually, all the iron in an object corrodes away even if it wasn’t initially at the surface.

Question 23

What is aluminium oxide?

Answer 23

Aluminium also corrodes when exposed to air. The aluminium oxide that forms when aluminium corrodes does not flake away. It forms a nice, protective layer that sticks firmly to the aluminium and stop any further reaction taking place.

Question 24

What methods can be used to prevent rusting?

Answer 24

Painting/coating with plastic
Electroplating
Oiling/greasing

Question 25

What is electroplating?

Answer 25

A way of preventing rusting. It uses electrolysis to reduce metal ions onto an iron electrode. It can be used to coat the iron with a layer of different metal that will not be corroded away.

Question 26

What is the sacrificial method?

Answer 26

Involves placing a more reactive metal such as zinc or magnesium with the iron. Water and oxygen then react with the sacrificial metal instead of with the iron.

Question 27

What are natural resources?

Answer 27

They form without human input. They include anything that comes from the earth, sea or air. E.g. cotton for clothing and oil for fuel.

Question 28

How can natural resourced be improved?

Answer 28

Some of the natural products can be replaced with synthetic products or improved upon by man-made product. E.g. rubber is a natural product that can be extracted from the sap of a tree, however, man-made polymers have now been made which can replace rubber in uses such a tyres.

Question 29

What are renewable resources?

Answer 29

They reform at a similar rate to, or faster than, we use them. E.g. timber.

Question 30

What are finite/non-renewable resources?

Answer 30

They are not formed quickly enough to be considered replaceable. E.g. fossil fuels and nuclear fuels such as uranium.

Question 31

What is sustainable development?

Answer 31

An approach to development that takes account of the needs of present society while not damaging the lives of future generations.

Question 32

How can the sustainability of copper be improved?

Answer 32

By extracting it from low-grade ores (ores without much copper in).

Question 33

What is bioleaching?

Answer 33

Bacteria are used to convert copper compounds in the ore into soluble copper compounds, separating out the copper from the ore in the process. The leachate (the solution produced by the process) contains copper ions which can be extracted by electrolysis or displacement with a more reactive metal.

Question 34

What is phytomining?

Answer 34

Growing plants in soil that contains copper. The plants cannot use or get rid of the copper so it gradually builds up in the leaves. The plants can be harvested, dried and burned in a furnace. The ash contains soluble copper compounds from which copper can be extracted by electrolysis or displacement using scrap iron.

Question 35

How are metals usually recycled?

Answer 35

By melting them and then casting them into the shape of the new product.

Question 36

What is life cycle assessment?

Answer 36

Life cycle assessment shows the total environmental costs. It looks at every stage of a product’s life to assess the impact it would have on the environment.

Question 37

What is the first stage of LCA?

Answer 37

Getting the raw materials -
Extracting raw materials needed for a product can damage the local environment e.g. mining materials. Extraction can also result in pollution due to the amount of energy needed.
Raw materials often need to be processed to extract the desired materials and this often needs large amounts of energy.

Question 38

What is the second stage of LCA?

Answer 38

Manufacture and Packaging-
Manufacturing products and their packaging can use lots of energy resources and can also cause loads of pollution e.g. harmful fumes.
You also need to think about any waste product and how to dispose of them. Some waste can be turned into other useful chemicals, reducing the amount that ends up polluting the environment.

Question 39

What is the third stage of LCA?

Answer 39

Using the product-
E.g. fertilisers can leach into streams.
How long a product is used for or how many uses it gets is also a factor - products that need lots of energy to produce but are used fro ages mean less waste in the long run.

Question 40

What is the fourth stage of LCA?

Answer 40

Product Disposal-
Products are often disposed of in landfill sites. This takes up space and pollutes land and water.
Energy is used to transport waste to landfill.
Products might be incinerated (burnt), which causes air pollution.

Question 41

What are the issues with life cycle assessment?

Answer 41

The effect of some pollutants is difficukt to give a numerical value to.
It is not an objective method. LCAs can be biased, depending of the person carrying out the assessment.

Question 42

What are selective LCAs?

Answer 42

They only show some of the impacts of a product on the environment. They can be written to deliberately support he claims of a company, in order to give them positive advertising.

Question 43

What is potable water?

Answer 43

Water you can drink. It has been treated and is naturally safe for humans to drink.
Chemists wouldn’t call it pure though. Potable water can contain lots of other dissolved substances. The level of dissolved salts are not too high, and that it’s pH between 6.5 and 8.5 and also that there is no bad bacteria.

Question 44

What are some sources of fresh water?

Answer 44

When it rains, water can be collected as surface water eg from reservoirs, or as groundwater eg in rocks called aquifers.

Question 45

What is the process to treat fresh water?

Answer 45

Filtration - a wire mesh screens out large twigs etc and then gravel and sand beds filter out any other solid bits.
Sterilisation - the water is sterilised to kill any harmful bacteria or microbes. This can be done by bubbling chlorine gas through it or by using ozone or ultraviolet light.

Question 46

What are water sterilising agents?

Answer 46

Chlorine gas, ozone or ultraviolet light.

Question 47

How can distillation be used to desalinate sea water?

Answer 47

Practical.

Question 48

How can sea water be treated?

Answer 48

Sea water can also be treated by processes that use membranes - like reverse osmosis. The salty water is passed through a membrane that only allows water molecules to pass through. Ions and larger molecules are trapped by the membrane so separated from the water.

Question 49

What is sewage screening?

Answer 49

Involves removing and large bits of material (like twigs or plastic bags) as well as any grit.

Question 50

What is sedimentation?

Answer 50

The sewage is allowed to stand in a settlement tank and undergo sedimentation - the heavier suspended solid sink to the bottom to produce sludge while the lighter effluent floats on the top.

Question 51

What is biological aerobic digestion?

Answer 51

The effluent in the settlement tank is removed and treated by biological aerobic digestion. This is where air is pumped through the water to encourage aerobic bacteria to break down any organic matter - including other microbes in the water.

Question 52

What is anaerobic digestion?

Answer 52

The sludge from the bottom of the settlement tank is also removed and transferred into large tanks. Here it is broken down by bacteria in a process called anaerobic digestion.
Anaerobic digestion breaks down the sludge, releasing methane gas in the process. The methane gas can be used as an energy source and the remaining digested waste can be used as a fertiliser.

Question 53

What additional stages of sewage treatment can be done for waste containing toxic substances?

Answer 53

Adding chemicals e.g. to precipitate metals.
UV radiation
Using membranes.

Question 54

What is the Haber process used for?

Answer 54

Used to make ammonia from hydrogen and nitrogen using the reversible reaction
nitrogen + hydrogen —> ammonia.

Question 55

Explain the Haber Process?

Answer 55

The nitrogen is obtained easily from the air -78% nitrogen.
The hydrogen mainly comes from reacting methane with steam to form hydrogen and carbon dioxide.
The reactant gases are passed over an iron catalyst. High temp (450 degrees celsius) and a high pressure are used.
As the reaction is revsersible, some of the ammonia produces back into nitrogen and hydrogen again. It eventually reaches a dynamic equilibrium.
The ammonia is formed as a gas, but as it cools in the condenser it liquifies and is removed. The unused hydrogen and nitrogen are recycled so nothing is wasted.

The ammonia produced can then be used to make ammonium nitrate - a very nitrogen rich fertiliser.

Question 56

What type of reaction is the forward reaction during the Haber process?

Answer 56

Exothermic. This means that increasing the temperature will love the equilibrium in the wrong way.
However, a lower temperature means a slower rate of reaction (and so equilibrium is reached more slowly).

Question 57

What catalyst is used during the production of ammonia?

Answer 57

Iron catalyst.

Question 58

What are NPK fertilisers?

Answer 58

NPK fertilisers provide plants with the essential elements for growth. Formulated fertilisers are better than manure because they are widely available, easier to use, do not smell and have the right amount of nutrients so that more crops can be grown.

They are formulations containing salts of nitrogen, phosphorus and potassium.

Question 59

What are the three main essential elements in fertilisers?

Answer 59

Nitrogen, phosphorus and potassium. These help to increase the crop yield.

Question 60

What is ammonia used for in agriculture?

Answer 60

Used to produce nitrogen-contaning compounds.
Ammonia can be reeacted with oxygen and water in a series of reactions to make nitric acid.
You can also react amonia with acids, including nitric acid, to get ammonium salts. Ammonia and nitric acids react together to produce ammonium nitrate - this is good for fertilisers.

ammonia + nitric acid = ammonium nitrate.

Question 61

How is the ammonium nitrate reaction carried out in industry?

Answer 61

Carried out in giant vats, at high concentration resulting in a very exothermic reaction. The heat released is used to evaporate water from the mixture to make a very concentrated ammonium nitrate product.

Question 62

How is the ammonium nitrate reaction carried out in the lab?

Answer 62

The reaction is carried out on a much smaller scale by titration and crystalisation. The reactants are at a much lower concentration than in industry, so less heat is produced by the reaction and it is safe for a person to carry out. After the titration, the mixture then needs to be crystalised to give pure ammonium nitrate crystals. Crystalisation isn’t used in industry because it is very slow.

Question 63

Where are phosphate and potassium sourced?

Answer 63

From mined compounds.
Potassium chloride and pottasium sulphate can be mined and used as a source of potassium.
Phosphate is rock is also mined. However, because sulphate rocks are insoluble, plantscannot use them as nutrients.

Question 64

What does the reaction between phosphate rock and nitric acid produce?

Answer 64

Phosphuric acid and calcium nitrate.