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Chemistry Revision


									Chemistry Revision
How did the oceans form?

  • Volcanoes gave out water vapour
  • Earth cooled
  • Water vapour condensed
How do the Oceans remove carbon dioxide 
  from the atmosphere? Card sort C1.2a
• Earth cooled
  – Water vapour condensed to form the oceans
  – Carbon dioxide dissolved in oceans
  – Halved carbon dioxide in atmosphere
  – Marine organisms use carbon dioxide to make 
    shells calcium carbonate
  – Die form sediment 
  – Million of years sedimentary rock.
  – Limestone = calcium carbonate
      What is photosynthesis?
• Below are some key words you can use them 
  to explain photosynthesis

     Oxygen (O2)    Carbon dioxide (CO2)
      Glucose (C6H12O6)   Water (H2O)
Carbon dioxide + Water à   Glucose + Oxygen
• Life began 4 billion years ago
• 1 billion years ago – organisms that 
• Takes in Carbon dioxide
• Gives out oxygen
Crude oil fractions assembly
      You have been given a series of cards
      with information about fractions of
      crude oil.

      Sequence the fractions as they are in
      a distillation column, then match the
      use to the fraction.

      You must also place the arrows in the
      correct direction to show the change
      in flammability, boiling point and
      molecule size.
The diagram summarises the main fractions from crude oil and their uses.
                  Catalytic Cracking
• Large hydrocarbons are broken into smaller
  molecules using heat and a catalyst.
• This process is known as catalytic cracking.
• The small molecules produced are then separated
  by distillation.

                                                         Smaller molecules
                Heat to     cracker
Big Molecules
                                  Molecules break
      Cracking - laboratory

reaction, with porcelain chips used as a catalyst
             Catalytic Cracking
• In the catalytic cracker long chain molecules are
  split apart or ‘cracked’. An example of such a
  reaction is:

hexane                                 catalyst

Used as a                                                    is used
fuel                                                         to make
                  C8H18  è  C6H14 + C2H4                     plastics

  • Draw out displayed formulae of a pair of products
    formed by cracking decane
                   H   H   H    H    H     H   H   H   H      H
               H   C   C   C    C    C     C   C   C   C      C   H

                   H   H   H     H   H     H   H   H   H      H


               H   H   H   H    H    H     H H

           H   C   C   C   C    C    C     C   C   H          +
               H   H   H   H    H    H     H H
      Exam technique - Cracking
Fuel oil contains large alkane molecules.
Fuel oil is cracked to make more useful products 
such as petrol.
Describe the cracking process. (2 marks)
A description including two of the
following points:

•large molecules form smaller molecules (1)

•(alkanes) form alkenes (1)

•use of heat (1)

•use of catalyst (1)
The table shows the percentage composition of one type
of crude oil and the
relative demand for each of the fractions.
fraction           percentage          relative demand
                   composition (%)
gases              4                   10
petrol             15                  28
kerosene           20                  5
diesel oil         37                  14
fuel oil           21                  3
bitumen            3                   1

Explain why cracking is necessary. (3 marks)
An explanation linking three of the
following points:

• surplus of larger molecules (diesel oil, fuel oil,

• shortage of petrol / gases (1)

• shorter chain molecules are more useful (1)

Acceptable answers:
alkenes formed (1)
(alkenes can be used) to make polymers (1)
                  Plenary - Higher
Write the word and balanced symbol 
     ethane + oxygen à   carbon dioxide + water 
equation for the complete combustion 
      2C2H6(g)  + 7O2(g)   à      4CO2(g)   +   6H2O(l) 
of ethane (2 carbons)  
    propane + oxygen à   carbon dioxide + water
and propane (3 carbons).
       C3H8(g)  + 5O2(g)  à    3CO2(g)   +   4H2O(l)   

Include state symbols
          Plenary - Foundation

Write the equation for the complete 
 ethane + oxygen à   carbon dioxide + water
combustion of ethane (C2H6).

What do fuels react with when they burn?
What products are formed?
   We will meet two types of hydrocarbon in this module

ALKANES    – single bonds between carbons

           - not very reactive although they burn well

           - used mostly as fuels

           - Saturated

ALKENES    – one carbon-carbon double bond in the molecule

           - very reactive

           - used to make plastics

           - Unsaturated
Which of these is an alkane?
A. C6H14
B. C4H8
C. C12H24
D. C102H204
Which of these is a true statement about

A. They turn bromine water from colourless to
B. They contain a double bond
C. The smallest alkene has 1 carbon atom
D. They have names that end in “ane.”
Which of these is a true statement about

A. it is the separation of molecules into
   fractions of different sizes.
B. it is carried out at low temperatures
C. it uses a catalyst.
D. It produces polymers
If octane is cracked and one of the products if
ethene what is the other product?

A.   Propane
B.   Propene
C.   Hexane
D.   Hexene
What is the general formula for an alkene

A.   2n
B.   2n+2
C.   3n
D.   n+2n
When bromine water is added to an
unsaturated compound it turns it from….

A.   Red to blue
B.   Green to yellow
C.   Orange to colourless
D.   Brown to orange
       The life of a plastic bottle
I will explain a section of the life of a plastic 
bottle. You have to identify which word card 
and picture card goes with what I am talking 

Some sections may have no picture, one picture, 
or more than 1 picture.
         Some uses of polymers

Ethene à polyethene
Plastic bags & bottles

Propene à polypropene
Crates & ropes

Chloroethene à polyvinylchloride
Drain pipes & insulation
          Exam technique – Polymers

Chlorine is used in the manufacture of the polymer
poly(chloroethene) (PVC).

Other similar polymers include poly(ethene) and

These polymers have similar properties and are widely used
in everyday life.

Describe a use for each of these polymers and explain how
the properties of the polymers relate to their uses.
(6 marks)
A description including some of the following points
• unreactive / inert
• do not break down / long lasting
• strong / hardwearing
• cheap
• easily moulded
• waterproof
• poly(ethene) used for food bags as waterproof and unreactive, moulded to make bottles as has a low 
melting point.
• poly(propene) used to make crates as rigid/strong, ropes as less dense than water/strong, chairs as easily 
• poly(chlorethene) used to make clothing/drainpipes as waterproof/unreactive 

1-2 • description of a use of one polymer with a related property/uses of two polymers/two typical properties 
           of polymers
        • the answer communicates ideas using simple language and uses limited scientific terminology
        • spelling, punctuation and grammar are used with limited accuracy

3-4 • description of the uses of at least two polymers with related properties/description of a use of one         
             polymer with a related property and uses or properties of two other polymers.
          • the answer communicates ideas showing some evidence of clarity and organisation and uses  
             scientific terminology appropriately
          • spelling, punctuation and grammar are used with some accuracy

5 - 6 • describe the uses of at least three polymers with related properties
         • the answer communicates ideas clearly and coherently uses a range of scientific terminology 
         • spelling, punctuation and grammar are used with few errors
                 Brainstorm biofuels –
What they are, how they are made, how they can be used
        and any advantages and disadvantages.

Some of the crops used as bio-fuels ……

     Rape seed                           Sunflowers

                        Sugar beet
          Dictogloss activity – biofuels

You will be read a paragraph of information biofuels

Sit and listen to it – do not write anything.

You will then be read the passage again during which you can 
make notes.

You will then get into pairs and together try and recreate the 
exact paragraph that has just been read.

Your pair will then get together with another group and as a 4 
try to replicate the finished paragraph.
Biofuels are obtained from living organisms or organisms that have 
recently died. Biofuels include wood and dried animal droppings, 
which have been used as fuels for hundreds of thousands of years 
and are still important as fuels today.

Chemists can manufacture biofuels from raw materials. Ethanol is 
made by processing wheat, sugar cane or sugar beet. Ethanol can 
be mixed with petrol for use as a fuel in car engines. Using ethanol 
helps to reduce the demand for petrol and so conserves crude oil 

Biodiesel is a fuel made from vegetable oils by chemical reactions. 
The oil can be produced from oil seed rape or soya beans or used 
cooking oil from restaurants.
Diesel engines can run on biodiesel or a mixture of biodiesel and 
normal diesel oil.
Are hydrogen fuel cells the way of the future?
 The space shuttle is on
orbit round the earth for
   normally 7-10 days.

It uses hydrogen fuel cells
to generate the electricity
         it needs.
    Complete starter sentences using connecting words such
        as ‘and’, ‘because’, ‘but’, ‘however’, ‘so’, ‘such as’,
                      ‘therefore’, ‘to’, ‘which’.

•   Iron seeding can help reduce global warming……
•   Making hydrocarbons from CO2 has other uses …….
•   Humans are contributing to global warming …….
•   The green house effect is causing many problems…….
•   Climate change needs to be stopped …….
Why is powdered calcium
carbonate sprayed through
chimneys in fossil fuel power

Why do farmers spray calcium
carbonate, calcium oxide and
calcium hydroxide on their fields?
                    Hazard symbols
These symbols may be in a triangle or a square, and a chemical
container might be labelled with more than one hazard symbol.
What do you think happens if you mix and acid with a

A salt is produced

     In science a salt is a substance we get from
   acid     +    base      è       a salt      +   water

          Reactants                         Products

Hydrochloric + Sodium è        Sodium          +       water
    acid      hydroxide        chloride

                      Table salt
              Examples of acids
sulphuric acid       H2SO4               SO4

hydrochloric acid     HCl
                                  H      Cl

nitric acid          HNO3           H    NO3

     What do all acids have in common?
      All acids have hydrogen in them
            Name of salts

    SO4   H2SO4             sulphates

H   Cl    HCl

H   NO3
          HNO3              nitrates
          Metal Carbonate + Acid
              Acid         A Salt   + Carbon + Water
Carbonate +                           Dioxide

 Calcium    Hydrochloric   Calcium + Carbon + Water
Carbonate +    Acid        Chloride Dioxide

   CaCO3 +     HCl          CaCl2   +   CO2   + H 2O
Metal oxides and acids

               Metal oxide + acid       è a salt + water

  zinc oxide      + sulphuric       è zinc          + water
                    acid              sulphate
     ZnO          +     H2SO4       è     ZnSO4     +    H 2O

  sodium          + hydrochloric è      sodium      + water
  oxide             acid                chloride

     Na2O         +      2HCl       è     2NaCl     +    H 2O

  iron oxide      + nitric acid     è iron nitrate + water

     Fe2O3        +     3HNO3       è    Fe(NO3)3   +   3H2O
                     Salt dice
In groups of 4 you will be given a pair of dice.

1 person takes a turn to roll both dice.

1 dice shows an acid, the other shows another compound.

Foundation - Your task is to try to write the word
equation for the reaction, naming all the products

Higher – Your task is to write the word and balanced
symbol equation, showing all the products formed.
When metal carbonates are heated they break
down to form metal oxide and carbon dioxide.

Reactions in which a substance breaks down to
form two or more other substances when heated
are called thermal decomposition.
For instance: heating copper carbonate (CuCO3)

copper carbonate          copper oxide + carbon dioxide
     green                     black         colourless
     solid                     solid             gas

   CuCO3       decomposition
                                  CuO   +   CO2
Write balanced equations for the thermal decomposition of:

CaCO3                        CaO     + CO2

MgCO3                        MgO + CO2

Na2CO3                       Na2O + CO2

Write balanced equations for the thermal decomposition of:

Calcium carbonate

Magnesium carbonate

Sodium carbonate

   Divide your page into a
      triangle like this

In the bottom section we will
write a summary of limestone
 and its uses in bullet points.

Highlight the most important
   words and ideas in that

 Write them out in the next
  section of the triangle.
                     Types of reactions
Exothermic        - gives out heat

Endothermic  - takes heat in 

Neutralisation           - acids and alkalis are neutralised 

Precipitation - two soluble salts react to for a 
              insoluble salt

Oxidation         - oxygen is added

Reduction         - oxygen is removed

Displacement - a more reactive metal pushes out a less reactive metal
           How to make an insoluble salt
                  Two solutions
                  of soluble salts

                                     Insoluble salt forms
                                     (precipitate) and
                                     falls to the bottom

When an insoluble salt has been produced by
precipitation reaction, it is filtered, washed on the
filter paper and dried in a warm oven.
An HCl tanker that crashes into an electricity pylon. HCl is
spilled all over the road and safety crews are called to the
scene. They instantly see that there is a problem with the HCl
because they can see the ‘corrosive’ hazard warning symbol!

However, suddenly, one of the broken electrical transmission
wires falls … suggest what will happen next.
                Opposite charges attract!!!

  Positively                                  Negatively
   charged                                     charged
   ions are                                    ions are
  attracted                                   attracted
    to the                                      to the
   negative                                     positive
  electrode.                                   electrode.

Positive ions                                 Negative ions
gain electron                                 lose electron
   at the                                         at the
  negative                                       positive
 electrode.                                     electrode.

   This is                                      This is
 reduction                                     oxidation.
 Electrolysis of Molten Al2O3
Write a word equation to describe the reduction
of aluminium oxide.
 ANODE                     +      -               CATHODE
                   The metal goes to
              +   the cathode and the
                   non metal goes to
                       the anode.

     O   2-
                                        O2-       O2-
     Al3+                             Al3+
Gas being tested   Observations


      What will the products of electrolysis of seawater be?

Sodium Chloride + Water à Chlorine + Hydrogen + Sodium Hydroxide

           2NaCl(aq) + 2H2O(l) à Cl2(g) + H2(g) + 2NaOH(aq)
                      Gas tests

Oxygen:                     Chlorine:

Put a lit splint into the   Put a damp piece of red
ignition tube containing    litmus paper in the
hydrogen.                   ignition tube containing
What do you observe
happen?                     What do you observe
It pops!!!
                            It turns blue then
                            bleaches white!!!
Produce a leaflet explaining about chlorine


•How chlorine is manufactured
•What is chlorine used for?
•Why is chlorine hazardous and what hazards will need to
be considered in its manufacture and transport.
•How do we test for chlorine?
Antiseptics              Plastics


                        Uses of       Making
                        Chlorine     chemicals

    Sterilising Water    Bleach     newspaper
           Dictogloss activity – uses of
              hydrogen and oxygen
You will be read a paragraph of information on the uses of 
hydrogen and oxygen.

Sit and listen to it – do not write anything.

You will then be read the passage again during which you can 
make notes.

You will then get into pairs and together try and recreate the 
exact paragraph that has just been read.

Your pair will then get together with another group and as a 4 
try to replicate the finished paragraph.
Uses of hydrogen and oxygen

Hydrogen has many uses one of the best known as is as
rocket fuel. Most of the hydrogen used is made from
substances obtained from oil, but this hydrogen often
contains traces of other substances. If the hydrogen has
to be very pure it is usually made by electrolysis.

We all need to breathe oxygen from the air around us. In
hospitals patients with breathing problems are often give
extra oxygen.

In enclosed spaces such as nuclear submarines and space
craft oxygen must either be carried in cylinders or made
using electrolysis
                          Structure of an alloy
Some metals e.g. copper, gold and aluminium are too soft for many uses.
So, they are mixed with other metals to make them harder for everyday use.

                                                      Other atoms are
                                                      added to a metal

         Brass – 70% copper + 30% zinc : electrical fittings
         18 carat gold – 75% gold + 25% copper : jewellery
         Duralumin – 96% aluminium + 4% copper : aircraft manufacture
              Rock cycle stepping stones

                                       and Erosion

Melting                                       Sedimentation

          Metamorphic                  Sedimentary
             Rocks                        Rocks

                        and Pressure
Carbon      HNO3          C4H10
            Sedimentary   Bacteria
            Alkene        Electrolysis
            Bromine       Sulphur dioxide
Bitumen     water
Alloy       Oxidation

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