Everyday Chemistry - PowerPoint PPT Presentation

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Everyday Chemistry

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Rusting Rusting is the corrosion of iron. Rusting results the iron object becoming weaker. Both oxygen (from the air) and water are required for rusting. – PowerPoint PPT presentation

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Title: Everyday Chemistry


1
Unit 2
Everyday Chemistry
2
Menu
  • To work through a topic click on the title.
  • Metals
  • Personal Needs
  • Fuels
  • Plastics
  • End

3
Metals
4
Finding Metals
  • Most metals are found combined with other
    elements.
  • These compounds are called ores.
  • Some metals, including gold, silver and copper,
    are found uncombined in the Earth's crust. This
    means that we can find the element on its own.

5
Extracting Metals
  • We get some metals, including iron, from their
    ores by heating the ore with carbon.

6
  • We get some metals, including aluminium, from
    their ores using electricity.

7
Using Metals
  • The properties of metals are the things it can do
    and the way it acts.
  • Metals are chosen for certain uses because of
    their properties.

8
  • Density of a metal is a measure of how heavy it
    is, compared to its volume.
  • That is why lead weights are used for fishing
    lines.

9
  • All metals are good conductors of heat i.e. they
    have a high thermal conductivity.
  • That is why metals are used for making pots and
    pans, radiators etc.

10
  • All metals are good conductors of electricity
    i.e. they have a high electrical conductivity.
  • That is why metals are used for making electrical
    wiring etc.

11
  • Metals are malleable. This means that they are
    easily made into new shapes.
  • This property is used when metals are made into a
    variety of objects, such as fencing, horse shoes
    etc.

12
  • Metals are strong.
  • Metals are used to make many things because of
    this strength e.g. car bodies, girders, tools
    etc.

13
Alloys
  • An alloy is a mixture of metals, or of metals
    with non-metals.
  • Many alloys have important uses.
  • Examples of alloys are
  • brass
  • solder
  • 'stainless' steel

14
Reactions of Metals
  • Metals react with many different materials.
  • By comparing reactions and seeing the differences
    between them we can recognise the reactivity of
    different metals.

15
  • Metals react with oxygen to produce metal oxides.
  • Magnesium Oxygen ? Magnesium oxide
  • Aluminium Oxygen ? Aluminium oxide

16
  • Some metals react with water to produce hydrogen.
  • Sodium Water ? Sodium hydroxide
    Hydrogen
  • Potassium Water ? Potassium hydroxide
    Hydrogen

17
  • Many metals react with dilute acid to produce
    hydrogen.
  • Some metals, including copper, silver and gold,
    do not react with dilute acid.
  • Zinc Hydrochloric acid ? Zinc chloride
    Hydrogen
  • Iron Sulphuric acid ? Iron sulphate Hydrogen

18
Test for hydrogen
  • The test for hydrogen is that it burns with a
    'pop'.

19
Corrosion
  • Corrosion is a chemical reaction.
  • In corrosion the surface of a metal changing from
    an element to a compound.
  • For corrosion to take place the metal must react
    with something in its surroundings.

20
Rusting
  • Rusting is the corrosion of iron.
  • Rusting results the iron object becoming weaker.
  • Both oxygen (from the air) and water are required
    for rusting.
  • Rust indicator can be used to show the extent of
    the rusting process.

21
  • Acid rain increases the rate of corrosion.
  • Salt spread on roads increases the rate of
    corrosion on car bodywork.

22
Preventing Corrosion
  • Physical protection prevents corrosion by making
    a surface barrier to air and water.
  • Now the metal cannot corrode because air and/or
    water cannot get at the metal.

23
Physical protection
  • Physical protection can be provided by
  • Painting
  • Greasing
  • Electroplating
  • Galvanising
  • Tin-plating
  • Coating with plastic

24
  • Chemical protection prevents corrosion by using
    chemicals.
  • Air and water can still get at the metal, but the
    chemicals prevent corrosion taking place.

25
Chemical protection
  • Chemical protection can be provided by
  • Iron does not rust when attached to more reactive
    metals so zinc (galvanising) and scrap magnesium
    are used to protect iron.
  • Anodising is a process which increases the
    thickness of the oxide layer on aluminium to
    provide protection against corrosion.

26
Batteries
  • In a battery, electricity comes from a chemical
    reaction.
  • Batteries require to be replaced due to the
    chemicals being used up in the reaction.
  • Examples of rechargeable batteries include the
    lead-acid battery and the nickel-cadmium battery.

27
Cells
  • Electricity can be produced by connecting
    different metals together, with a solution
    containing ions, to form a cell.
  • The ion solution completes the circuit.
  • The voltage between different pairs of metals
    varies.
  • The size of the voltage depends on the difference
    in reactivity of the metals.

28
Metals
  • Click here to repeat Metals.
  • Click here to return to the Menu
  • Click here to End.

29
Personal Needs
30
Keeping clean
  • When cleaning hair, skin and clothes the main
    problem is oil and grease.
  • This is because oil and grease do not dissolve in
    water.

31
  • Cleaning chemicals are required to break up the
    oil and grease into tiny droplets
  • These droplets can then mix with water
  • This happens because cleaning chemicals dissolve
    in both water and oil and grease.

32
  • Some manufactured products contain cleaning
    chemicals.
  • Some are
  • Soaps
  • Detergents
  • Shampoos
  • Washing-up liquids and powders.

33
  • Some soaps form a scum with hard water.
  • Soapless detergents are used to form a lather
    with hard water.
  • Dry-cleaning uses special solvents which are
    particularly good at dissolving oil and grease
    stains.

34
Clothing
  • Clothing fabrics are made from thin strands
    called fibres.
  • Fibres are made up of long chain molecules called
    polymers.

35
  • Natural fibres come from plants and animals.
  • Some natural fibres are
  • silk
  • wool
  • cotton

36
  • Synthetic fibres are made by the chemical
    industry.
  • Some synthetic fibres are
  • Nylon
  • Polyesters (e.g. Terylene)

37
  • Synthetic fibres can be used to make fabrics
    which have particular uses.
  • Dyes are coloured compounds, which are used to
    give bright colours to clothing.

38
  • Chemists have developed ways of treating fabrics
    to improve their properties.
  • Some fibres form strong bonds with water
    molecules
  • These fibres are hard to drip-dry but they do not
    feel 'sweaty' to wear because they soak-up
    perspiration.

39
Personal Needs
  • Click here to repeat Personal Needs.
  • Click here to return to the Menu
  • Click here to End.

40
Fuels
41
Fire
  • A fuel is a chemical, which is burned to produce
    energy.
  • When a substance burns it reacts with oxygen.
  • Combustion is another word for burning.

42
  • A fire needs
  • Fuel
  • Oxygen (usually from the air)
  • A temperature high enough to start the fire and
    keep it going
  • Take away anyone of the three and the fire goes
    out.

43
Putting out fire
  • Fire-fighting methods in the lab and the home
    include using
  • Fire blanket
  • Sand
  • Water
  • Carbon dioxide gas
  • Foam.

44
  • Different methods of putting out the fire are
    used in different situations.
  • Water must not be used with oil, petrol and
    electrical fires.

45
Fossil fuels
  • Fossil fuels are formed from animal and plant
    remains over a very long period of time.
  • Fossil fuels include
  • Coal
  • Natural gas
  • Oil
  • Peat.

46
Finite Resources
  • Fossil fuels are finite resources, i.e. they
    cannot be replaced.
  • If we use too much of the fossil fuels a fuel
    crisis will result, when most of the fossil fuels
    have been used up.

47
Hydrocarbons
  • The compounds, which are found in fossil fuels
    are mainly hydrocarbons.
  • A hydrocarbon is a compound which contains
    hydrogen and carbon only.
  • Hydrocarbons burn in a plentiful supply of air to
    produce carbon dioxide and water.
  • Hydrocarbon Oxygen ? Carbon Dioxide
    Water

48
Renewable resources
  • Renewable resources are energy resources which
    can be replaced.
  • Some renewable sources of energy are
  • Methane
  • Ethanol
  • Hydrogen

49
  • Methane is found in biogas, which is made by the
    breaking down of waste plant material.
  • Ethanol is made from sugar cane and can be mixed
    with petrol to make a fuel for cars,
  • Hydrogen, which can be made from water, is a
    likely fuel for the future.

50
Fractional Distillation
  • Crude oil is a mixture of hydrocarbons.
  • A fraction is a group of hydrocarbons with
    boiling points within a given range.

51
  • Fractional distillation is the process which
    separates crude oil into different fractions
    according to their boiling points.

52
Fractions
  • Hydrocarbons made of small molecules boil more
    easily than hydrocarbons made of large molecules.
  • Different fractions are used as different fuels.

53
  • The uses of the fractions is decided by their
    properties.
  • How easy it is to make them turn into a gas
    (evaporate)
  • Their thickness (viscosity)
  • How easy they are to burn (flammability)
  • Their boiling point range

54
Cracking
  • Fractional distillation of crude oil gives more
    long chain hydrocarbons than are needed.
  • Cracking is an industrial method for producing a
    mixture of smaller, more useful molecules.

55
Water Pollution
  • Oil spillages can cause great damage to marine
    life and the environment.

56
Air Pollution
  • Soot (carbon) and carbon monoxide, a poisonous
    gas, can be produced when hydrocarbons burn in a
    low supply of oxygen.
  • The burning of some fuels releases sulphur
    dioxide, a poisonous gas, into the atmosphere.

57
  • Nitrogen and oxygen from the air can react inside
    a car engine to form nitrogen dioxide which is a
    poisonous gas.
  • Lead compounds which used to be added to petrol
    cause pollution.
  • Benzene fumes in unleaded petrol are toxic.

58
  • Soot particles, produced when diesel fuel does
    not burn properly, are harmful.
  • Air pollution from the burning of hydrocarbons
    can be reduced by the use of catalytic converters
    which convert the pollutant gases to harmless
    gases.

59
Fuels
  • Click here to repeat Fuels.
  • Click here to return to the Menu
  • Click here to End.

60
Plastics
61
Plastics
  • Plastics are synthetic materials, i.e. made by
    the chemical industry.
  • Most plastics are made from oil. 
  • Examples of plastics include polythene,
    polystyrene, perspex, PVC, nylon, Kevlar,
    bakelite, formica and silicones.
  • The properties of plastic help to decide what
    they are used for.

62
Advantages and disadvantages of plastics
  • For some uses, plastics have advantages over
    natural materials and vice versa.
  • Biodegradable materials are broken down by
    bacteria in the soil and rot away.

63
  • Most plastics are not biodegradable and their
    durability and lightness can cause environmental
    problems.
  • Some degradable plastics have been developed by
    chemists to ease the problems of plastic waste.

64
Disposing of plastics
  • Some plastics burn or smoulder to give off toxic
    fumes, including carbon monoxide.
  • We can get rid of plastics by burning, recycling
    and burying.
  • With burning the heat produced can be used as a
    source of energy but there are problems with
    gases given off.

65
Recycling plastics
  • Since oil is a finite resource, recycling is to
    be encouraged and chemists are looking for
    renewable sources of plastics.
  • Recycling can be difficult because of the many
    different kinds of plastic in common use.

66
Different plastics
  • Plastics can be either thermoplastic or
    thermosetting.
  • A thermoplastic is one which can be reshaped on
    heating.
  • A thermosetting plastic cannot be reshaped by
    heating.
  • The uses of thermosetting plastics are decided by
    their heat and electrical insulation properties.

67
Making plastics
  • Plastics are made up of polymers.
  • These are very long molecules, made by joining
    together many small molecules.

68
  • Polymer molecules are made from many small
    molecules called monomers.
  • The process of making a polymer by joining many
    monomers together is called polymerisation.
  • Ethene monomers form poly(ethene), also called
    polythene the styrene monomers form
    poly(styrene).

69
Plastics
  • Click here to repeat Plastics.
  • Click here to return to the Menu
  • Click here to End.

70
The End
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