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Title: IGCSE Chemistry - Exam Revision 2016
Description: Exam revision notes for the 2016 updated syllabus of "Coordinated Sciences (Double Award)". Concise and explanatory, but detailed, revision guide for chemistry in the coordinated sciences syllabus. Explains every point on the syllabus, and shows equations when needed.
Description: Exam revision notes for the 2016 updated syllabus of "Coordinated Sciences (Double Award)". Concise and explanatory, but detailed, revision guide for chemistry in the coordinated sciences syllabus. Explains every point on the syllabus, and shows equations when needed.
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1
Chemistry: IGCSE -‐ Exam Revision
C1
...
1 and P4
...
1
...
Atom:
• The smallest particles of matter, that we cannot break own further by chemical means
...
Molecule:
• When atoms of the same element join together we get a molecule of that element
...
Two oxygen atoms join together to make an oxygen molecule
...
Hydrogen and chlorine also have molecules with two
atoms
...
Sulfur atoms can make molecules of eight
atoms joined together
...
State the distinguishing properties of solids, liquids and gases
...
Solids have a fixed shape and cannot flow
...
Solids cannot be compressed or squashed
...
The particles cannot move from place to place
...
The particles are close together and have no space to move into
...
Liquids flow and take the shape of their container
...
Liquids cannot be compressed or squashed
...
The particles can move around each other
...
The particles are close together and have no space to move into
...
Gases flow and completely fill their container
...
Gases can be compressed or squashed
...
The particles can move quickly in all directions
...
The particles are far apart and have space to move into
...
Describe qualitatively the molecular structure of solids, liquids and gases
...
• Particles vibrate around a fixed point, so has little freedom of movement
...
• The liquid takes the shape of its container
...
• Intermolecular forces between particles are pretty weak
...
Relate the properties of solids, liquids and gases to the forces and distances between molecules and to the motion
of the molecules
...
Liquid:
• The distance here is not as close as that of the solids, but the particles are still quite close together, and the
forces between the particles are still quite strong
...
Gas:
• Particles are very far apart here
...
5
...
Temperature of a Gas:
• The temperature of a substance is proportional to the kinetic energy of the molecules
...
o If the temperature of the gas decreases, it will have less kinetic energy, as particles move around
slower and they will have less energy
...
Describe qualitatively the pressure of a gas in terms of the motion of its molecules
...
Pressure of a Gas:
• The motion of molecules in a substance causes the collision of these molecules on the wall of the container
...
• When the pressure of a gas increases, the movement of particles increases (faster) – more kinetic energy
...
7
...
Pressure, Volume, Temperature:
• Temperature = Pressure * Volume
Constant Volume:
• When volume is constant – pressure and temperature is proportional
...
• If you decrease the volume of the container, the pressure increases as the number of particles hitting each
cm3 of the container wall will increase
...
o Greater volume – smaller pressure (less kinetic energy)
o Smaller volume – greater pressure (more kinetic energy)
C2
...
1 Methods of separation and purification
1
...
Chromatography:
• Chromatography can be used to separate mixtures of coloured compounds
...
2
...
Procedure:
• Simple chromatography is carried out on paper
...
water)
...
• Different components of the mixture will move at different rates
...
Retention Factor Values:
• The movement of a substance during chromatography, relative to the movement of the solvent, is measured
by calculating its retardation factor (Rf)
...
Interpretation:
• A chromatogram can be compared with a chromatogram of a standard reference material to identify which
chemicals the mixture contained
...
o In this case, locating agents can be used to show where the spots are
...
• Another chemical can be added, which reacts with the locating agent to produce a coloured spot
...
Describe methods of separation and purification: filtration, crystallization, distillation, fractional distillation
...
• If a substance does not dissolve in a solvent, we say that it is insoluble
...
Used When:
• Filtration is a method for separating an insoluble solid from a liquid
...
o the water passes through the filter paper (it becomes the filtrate)
...
There is filter paper in a filter funnel above
another beaker
...
• The liquid particles are small enough to pass through the filter paper as a filtrate
...
Crystallization:
• To separate: the solute from a solution
...
o A saturated solution can dissolve no more solute, at that temperature
...
Procedure:
• Heat the solution, to evaporate some solvent
...
o If crystals form on the rod, you know the solution is saturated
...
o As it cools, crystals of the solute form
...
Wash them with a little distilled water
...
• The solvent boils off as a gas, at its boiling point
...
• The solute remains in the flask
...
• Suppose A has the lower boiling point
...
o Collect liquid A – stop collecting when the temperature
on the thermometer rises
...
o Gas B passes into the condenser, at B’s boiling point
...
5
6
4
...
g
...
Importance of Purity:
• It is essential to make sure some substances are pure
...
• Foodstuff: Purity in foodstuff and drugs can be very important to make sure that what we are consuming is
what we are expecting to consume
...
• Medicine: If there are different things in it than what is intended, the patient may not get better and may even
get much worse
...
Identify substances and assess their purity from melting point and boiling point information
...
• Melts and boils at temperatures that are unique to it
...
• Melts sharply at its melting point
...
• Melts over a range of temperature, not sharply
...
o Boils at a higher temperature than the pure substance
...
• Identify an unknown pure substance, by measuring its melting and boiling points, and then looking these up
in tables
...
Suggest suitable purification techniques, given information about the substances involved
...
Terminology:
• Mixture – 2 or more substances that are not chemically combined
...
• Solute – the substance that you dissolve
...
Separation Methods:
• Filtration: To separate an insoluble solid from a liquid
...
• Simple Distillation: To separate the solvent from a solution
...
Atoms, elements and compounds
3
...
Identify physical and chemical changes, and understand the differences between them
...
• Examples:
o Rotting fruit
o Mixing chemicals
o Tarnishing silver
7
Physical Changes:
• Changes that affect the form of an object, but does not have any effect on its chemical composition
...
o Crumpling a piece of paper
Differences Between Them:
1
...
• Ex: the freezing of water would be a physical change because it can be reversed, whereas the burning of
wood is a chemical change – you can’t ‘un-‐burn’ it
...
A physical change is a change in which no new substance is formed; a chemical change results in the
formation of one or more new substances
...
all new substances which were not there from the start
...
2 Elements, compounds & mixtures
1
...
Element:
• One kind of substance, cannot be separated into simpler substances
...
Mixture:
• Physical blend of two or more substances, not chemically combined
...
Demonstrate understanding of the concepts of element, compound and mixture
...
• Each atom consists of a nucleus and particles called electrons that whizz around the nucleus
...
Periodic Table:
• The groups of elements that have similar properties are put in a numbered column
...
• The zig-‐zag line separates metals from non-‐metals, with the non-‐metals on the right
...
• The symbol for compound is made from the symbols of the elements in it
...
3
...
Describe the structure of an atom in terms of electrons and a nucleus containing protons and neutrons
...
• Atoms are themselves made up of smaller particles: protons, electrons, and neutrons
...
•
• These particles have so little mass that it is not given in grams
...
8
• Because they make up the atoms -‐ protons, neutrons, and electrons are called subatomic particles
...
The protons and neutrons form a nucleus in the centre of the atom
...
2
...
3
...
• The energy levels are called shells
...
Electrons have negligible mass
...
The nucleon number tells us the
relative atomic mass of the atom
...
Protons:
• The number of protons in an atoms tells you which element it belongs to
...
• In the periodic table atoms are arranged in atomic number order
...
• An atom has no overall charge, so the (+) and (–) charges must balance each other
...
2
...
Periodic Table:
• Electrons are arranged in shells
...
o 1st energy level holds up to 2 electrons
o 2nd energy level holds up to 8 electrons
o 3rd energy level holds up to 8 electrons
...
Explanation:
• If an atom is in its 3rd energy level holding 8 electrons, the
addition of 1 more electrons will push it to the 4th energy
level
...
o We call these Noble Gases
...
o It fills up first – is at the lowest energy level
...
o It fills up next
...
o The next 2 go into the fourth shell – after that the rest of the third shell fills
...
3
...
Particle
Mass – in relative atomic mass units
Charge
Proton (p)
1
1+ (positive)
Neutron (n)
1
No charge
Electron (e)
1/1840 (almost nothing – 0)
1-‐ (negative)
4
...
Proton Number:
• The atomic number (also called the proton number) is the number of protons in an atom
...
5
...
Explanation:
• Elements are arranged in order of their proton number, row by row
...
• The period number shows how many shells there are
...
o The outer-‐shell electrons are often called the valency electrons
...
o All the elements in Group I have similar reactions, because their atoms all have one outer-‐shell
electron
...
• This arrangement makes these atoms stable -‐ Group VIII elements are unreactive
...
Where the element is in the Period Table
Element
Bromine, Br
Krypton, Kr
Rubidium, Rb
Strontium, Sr
Proton
Number
(= number of
electrons)
35
36
37
38
Period (how many shells its atoms
have)
4
4
5
5
Group (how many outer-‐shell
electrons there are; Group VIII has a
full outer shell)
VII
VIII
I
II
Electron
Distribution
2 + 8 + 18 + 7
2 + 8 + 18 + 8
2 + 8 + 18 + 8 + 1
2 + 8 + 18 + 8 + 2
10
6
...
What are isotopes?
• The atoms of an element are not always identical
...
o They can have different numbers of neutrons
...
• Each isotope has a different relative atomic mass – sometimes asked to find the average relative atomic
mass of the different isotopes
...
Radioactive Isotopes:
• Some isotopes are unstable
...
o These isotopes are called radioactive
...
Radiation:
• Radiation consists of tiny particles, and rays
...
• Medical uses:
o In treating cancer, radiation is used to kill cancer cells – Cobalt-‐60 is usually used for this
...
§ Ex: Iodine-‐131 is used to se if the thyroid gland is working properly, the thyroid absorbs iodine
...
Radiation can be detected at the
leak, using an instrument called a Geiger counter
...
§ Ex: To keep foods (like fruit and meat) fresh for longer
...
4 Ions & Ionic Bonds
1
...
Ions:
• Atoms or group of atoms that carry a charge, because they have gained or lost electrons
...
2
...
Ionic Bonding:
• Ionic bonds form only between metal and non-‐metal atoms
...
• The ions are stable, because they have the same arrangement of outer-‐shell electrons as a noble gas atom
does
...
Groups I & VII:
Example: Sodium Chloride
• A sodium atom transfers its outer electron to a chlorine atom, giving a positive sodium ion and a negative
chloride ion
...
11
•
The bonding is the same in any compound formed between an alkali metal (Group I) and a halogen (Group
VII)
...
Explain the formation of ionic bonds between metallic and non-‐metallic elements
...
• Electrons are transferred from the metal atom to the non-‐metal atom, to give ions of opposite charge
...
• The ions are then attracted to each other (opposite charges attract)
...
• Conduct electricity when melted or dissolved in water
...
4
...
Lattice Structure:
• Millions of ions group together to form a lattice
...
• They are held together by the strong ionic bonds between ions of opposite charge
...
12
3
...
State that non-‐metallic elements form non-‐ionic compounds using a different type of bonding called covalent
bonding
...
• They are formed:
o Between the atoms in a non-‐metal element
...
• The purpose is to gain the same arrangement of outer-‐shell electrons as a noble gas atom – because that is a
stable arrangement
...
• Shapes: The electron pairs around an atom repel each other, so they try to get as far apart as possible
...
• Do not conduct electricity – no charge
...
2
...
H2: Cl2: H2O:
HCl: CH4:
3
...
Covalent (Molecular) Compounds
Ionic Compounds
• Have low melting and boiling points
...
• Many are gases or liquids at room temperature
...
• Evaporate readily – they are volatile
...
• Do not conduct electricity
...
• Are insoluble in water, but dissolve in organic
• Are usually soluble in water
...
13
4
...
N2:
C2H4:
CO2:
3
...
Describe the giant covalent structures of graphite and diamond
...
structure
...
Giant
Each carbon atom forms a tetrahedron with 4 Each carbon atoms becomes part of a flat
Structure other carbon atoms
...
Forces
All the covalent bonds are identical, and
strong
...
Properties -‐ Very high melting point, because all the
bonds are strong
...
But the layers are held together by weak forces
...
14
-‐ Very hard, because all bonds are strong
...
-‐ Insoluble in water
...
-‐ Good conductor of electricity, because the free
electrons between the layers can move
...
Uses
-‐ Cutting tools
...
-‐ Jewelry
...
2
...
Graphite -‐ Lubricant:
• The layers between the graphite are very weak, so the layers of covalently bonded carbons can easily “slide”
over each other
...
Diamond – Cutting:
• The covalent bonds joining the carbons are very strong
...
3
...
Silicon Dioxide – A Macromolecular Compound:
• Silicon dioxide or silicon (IV) oxide, SiO2, is a macromolecular compound
...
• The bonds are strong – similar properties to diamond:
o Very high melting point
o Very hard
o Non-‐conductor of electricity
o Insoluble in water
• Used in sandpaper, and to line furnaces
...
• Each silicon atom forms covalent bonds with 4 oxygen bonds
...
C4
...
Use the symbols of the elements to write the formulae of simple compounds
...
• Below are the formulae of some chemical compounds that you may have come across before:
o Water: H2O
o Hydrochloric acid: HCl
15
o Sulphuric acid: H2SO4
2
...
Deducing the Formula:
• For example, if we are told that a certain compound contains both sodium and chlorine, we can deduce its
formulae to be NaCl
...
3
...
Deducing the Formula:
• A simple way would be to count the number of electrons in each atom
...
o Diagram features an ionic compound -‐ take in account the single electron given from the positive ion to
complete its full outer shell
...
o The element on the right has 17 electrons
...
4
...
Word Equations:
• Example:
o The compound contains sodium and chlorine; hence we can deduce its identity to be sodium chloride
...
Determine the formula of an ionic compound from the charges on the ions present
...
• Example:
o A compound has Fe2+ ions present as well as Cl– ions
...
o The formula of the ionic compound must be FeCl2
...
Construct and use symbolic equations with state symbols, including ionic equations
...
Deduce the balanced equation for a chemical reaction, given relevant information
...
Define relative atomic mass, Ar
...
• On the periodic table, to work out the relative atomic mass of an element, you simply look at
the mass number of the element, a sum of the number of the protons and neutrons present
...
Define relative molecular mass, Mr , as the sum of the relative atomic masses (relative formula mass or Mr will be
used for ionic compounds)
...
It is the sum of the relative atomic mass of the atoms present within the compound
...
o Na = 23, N = 14, O = 16
...
4
...
Define the mole in terms of a specific number of particles called Avogadro’s constant
...
)
The Mole Concept:
• The mass of an atom of carbon-‐12 is taken as 12 – so the Ar of carbon is 12
...
o Follows that 24 grams of magnesium contains the same number of atoms as 12 grams of carbon does
...
A mole of a substance is the amount that contains as many elementary units as the number of atoms in 12g
of carbon-‐12
...
02 x 1023
• Ex: 24g of magnesium contains 6
...
Avogadro’s Law states that equal volumes of all gases, at the same temperature and pressure, contain the
same number of particles
...
Examples:
Substance
Ar or Mr
So 1 mole of it is
...
Helium, He
4
4 grams
6
...
02 x 1023 oxygen molecules
2
...
•
•
•
17
3
...
(Calculations involving the idea of limiting reactants may be set
...
• Units used: g/dm3 or mol/dm3
• Remember: 1 dm3 = 1 liter = 1000 cm3
o The molar volume is the volume occupied by one mole of a gas
...
Electricity and chemistry
1
...
Electrolysis:
• The chemical effect of electricity on ionic compounds, causing them to break up into simpler substances,
usually elements
...
2
...
Electrode:
• A conductor in which electricity enters or exits a substance
...
For
electro-‐plating
...
Cathode:
• The negative electrode in which cations (+ ions) are attracted to
...
Describe electrolysis in terms of the ions present and the reactions at the electrodes
...
Explanation:
• Electrolysis requires that the chemical compound is ionic
...
• However, by dissolving it in water the ions are able to move freely within the solvent
...
4
...
State and use the general principle that metals or hydrogen are formed at the negative electrode (cathode), and
that non-‐metals (other than hydrogen) are formed at the positive electrode (anode)
...
If the metal is more reactive than hydrogen, hydrogen forms
...
2
...
A non-‐metal other than hydrogen forms at the anode (+):
1
...
2
...
19
6
...
Introduction:
• Electrolysis can also be used to purify metals
...
Purification of Copper:
• Normally, to extract elements from ionic compounds, you would use carbon rods as electrodes to extract the
element you want from the electrolyte
...
• The impure copper would be used as the anode & the pure copper would be used as the cathode
...
o This is to prevent other metals from being produced at the cathode
...
• They are then attracted to the copper cathode and the copper ions are reduced and deposited at copper
cathode: Cu2+ + 2e– —> Cu
• As the reaction continues, the copper cathode grows larger in size while the anode becomes thinner
...
7
...
Electroplating:
• One metal is coated with another to protect it against corrosion, or make it look more attractive
...
o Steel taps or car bumpers are coated with chromium, to make them look shiny
...
o Use the object as the cathode (-‐)
...
8
...
Predicting:
• Most commonly used compound: NaCl
...
• Whilst separating NaCl solution, make sure you understand that the positive ions are reduced in the cathode,
and negative ions are oxidized in the anode
...
• So, the separation will become something like this:
• At the cathode: Na+ (l) + e– → Na (l)
• At the anode: 2Cl– (l)→ Cl2(g) + 2e–
9
...
Aluminum from pure aluminium oxide in molten cryolite:
20
Aluminium ore is called bauxite
...
The extraction is done by electrolysis
...
• Aluminium oxide has a very high melting point (over 2,000°C), so it would be expensive to melt it
...
• The use of cryolite reduces some of the energy costs involved in extracting aluminium
...
• Aluminium metal forms at the negative electrode and sinks to the bottom of the tank, where it is tapped
off
...
o This oxygen reacts with the carbon of the positive electrodes, forming carbon dioxide, and they
gradually burn away
...
• A solution of sodium hydroxide forms
...
• During electrolysis:
o Hydrogen ions H+ (from the water) are discharged at the negative electrode as hydrogen gas, H2
o Chloride ions Cl– are discharged at the positive electrode as chlorine gas, Cl2
o Sodium ions Na+ and hydroxide ions OH– (from the water) stay behind -‐ they form sodium hydroxide
solution, NaOH
The 3 Product of Electrolysis:
• Hydrogen is used as a fuel and for making ammonia
• Chlorine is used to kill bacteria in water, and to make bleach and plastics
• Sodium hydroxide is used to make soap and bleach
C6
...
1 Energetics of a reaction
1
...
Exothermic & Endothermic Reactions:
• Chemical reactions transfer energy to, or from, the surroundings
...
• Example:
o When a bonfire burns, it transfers heat energy to the surroundings
...
o The temperature rise can be measured with a thermometer
...
Exothermic Reactions:
• Exothermic reactions transfer energy to the surroundings
...
o The release of heat means that an exothermic reaction increases temperature of the surroundings
...
•
•
•
•
•
•
21
The reactants have more energy than the products here, so a small amount of energy is required to activate
the reaction
...
• The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get
colder
...
• The temperature decrease can also be detected using a thermometer
...
Demonstrate understanding that exothermic and endothermic changes relate to the transformation of chemical
energy to heat (thermal energy), and vice versa
...
o Often called Energy of Activation because this energy is essentially required to start the reaction
...
o The bonds then subsequently rearrange and bond again, which releases energy
...
• If the energy given to activate is more than the energy released during the bond formation, the reaction is
endothermic
...
C7
...
1 Speed of reaction
1
...
Particle Size (Surface Area):
• Increasing the surface area will increase the rate of reaction
...
• Example:
o Q: Which reacts faster, magnesium or magnesium powder?
o A: Powder, because the powder has a much larger surface area, hence increasing the rate of reaction
...
• Increasing the concentration results in there being more particles in each cm3 of space, so there will be more
frequent collisions between particles
...
o This explains for a slower rate of reaction as the reaction proceeds for a period of time
...
• There are two important reasons for this:
o Particles will move faster and have more kinetic energy, so there will be more collisions per second
...
Catalysts:
• Adding a catalyst increases the rate of reaction, but it itself is not used up in the reaction
...
Summary:
• When you increase the temperature by heating, the rate increases
...
• When you increase the surface area of a solid reactant by using smaller pieces (larger total surface area), the
rate increases
...
• When you decrease the concentration of a reactant by using a more dilute solution, the rate decreases
...
Measuring:
• Measure the rate at which a reactant is used up
...
Average rate of reaction (cm3/min or sec) =
𝐭𝐨𝐭𝐚𝐥 𝐯𝐨𝐥𝐮𝐦𝐞 𝐨𝐟 𝐠𝐚𝐬 𝐜𝐨𝐥𝐥𝐞𝐜𝐭𝐞𝐝 (𝐜𝐦𝟑)
𝐭𝐨𝐭𝐚𝐥 𝐭𝐢𝐦𝐞 𝐭𝐚𝐤𝐞𝐧 (𝐦𝐢𝐧 𝐨𝐫 𝐬𝐞𝐜)
•
•
The mass of a substance -‐ solid, liquid or gas -‐ is measured with a balance
...
The Rate is Increased If:
• The temperature is increased
• The concentration of a dissolved reactant is increased
• The pressure of a reacting gas is increased
• Solid reactants are broken into smaller pieces
• A catalyst is used
Graphing:
• Volume: x-‐axis
...
23
2
...
Apparatus:
• Gas syringe
• 2x Reactants
• Stopwatch
• Conical Flask
Procedure:
1
...
2
...
3
...
4
...
(6
...
)
As more gas is produced, the plunger is pushed out and
the volume of the gas in the syringe can be recorded
...
Devise a suitable method for investigating the effect of a given variable on the speed of a reaction
...
o For one experiment use, “x” concentration of HCl
...
Temperature:
• Repeat the experiment above, but this time with 2 different types of temperatures of HCl, and compare the
differences of volume of gas produced
...
o Higher temperature leads to a higher rate of reaction
...
magnesium)
...
magnesiums) you should use are:
1
...
2
...
Catalysts:
• Again, repeat the experiment two times again
...
o Once without a catalyst
...
Interpret data obtained from experiments concerned with speed of reaction
...
o
o
o
24
The graph is steepest in the end – the rate of reaction is fastest in the end
...
The graph eventually levels off at a plateau -‐ volume of gas produced does not further increase
...
Describe the application of the above factors to the danger of explosive combustion with fine powders (e
...
flour
mills) and gases (e
...
mines)
...
o In flour mills, the air can fill with fine flour dust, with a very large total surface area
...
o In coal mines, methane and other flammable gases can collect in the air
...
6
...
Temperature:
• Increasing the temperature will give the particles more kinetic energy, so the frequency of collisions
between particles will increase and the number of successful collisions will also increase
...
• Increasing the concentration results in there being more particles in each cm3 of space, so there will be more
frequent collisions between particles
...
o This explains for a slower rate of reaction as the reaction proceeds for a period of time
...
Define catalyst as an agent which increases rate but which remains unchanged
...
• You can reuse the catalyst after a reaction because it is unchanged
...
2 Redox
1
...
Oxidation:
• Oxygen is gained
...
o The loss or removal of electrons from an atom, ion or molecule
...
Reduction:
• Oxygen is lost
...
o The gain or addition of electrons to an atom, molecule or ion
o A reducing agent is the species that removes the oxygen and “donates” the electrons
...
2
...
Redox Reaction:
• Reduction and oxidation always take place together, in a reaction – a redox reaction
...
Oxidation is loss and reduction is gain -‐ happens simultaneously
...
Identification:
• If one reactant is oxidized, and another is reduced
...
Acids, bases and salts
8
...
Describe neutrality and relative acidity and alkalinity in terms of pH (whole numbers only) measured using full-‐
range indicator and litmus
...
• The color it changes to depends on the pH of the substance
...
• If we want to test for acidity, we use blue litmus paper
...
• The following results are:
o Acids: Turn blue litmus paper red
...
o Neutral: No color change
...
Describe the characteristic reactions between acids and metals, bases (including alkalis) and carbonates
...
• This reaction is called neutralization
...
acid + base → salt + water
2
...
acid + metal hydroxide → salt + water
• Remember that most bases do not dissolve in water
...
• Reaction 2:
o Amount of metal oxide decreases
o Temperature increases (exothermic reaction)
o Solution changes color
• Reaction 3:
o Hydroxide starts to disappear
o Temperature increases (exothermic reaction)
26
Carbonates:
• When acids react with carbonates, such as calcium carbonate (found in chalk, limestone and marble), a salt,
water and carbon dioxide are made
...
acid + metal carbonate → salt + water + carbon dioxide
• Notice that an extra product -‐ carbon dioxide -‐ is made
...
• Characteristics:
o Metal carbonate starts to disappear
o Temperature rises (exothermic reaction)
o Color change
Reactive Metals:
• Acids will react with reactive metals, such as magnesium and zinc, to make a salt and hydrogen
...
acid + metal → salt + hydrogen
• The hydrogen causes bubbling during the reaction, and can be detected using a lighted splint
...
Describe and explain the importance of controlling acidity in the environment (air, water and soil)
...
• If soil is too acidic or too alkaline, crops grow badly or not at all
...
• Because of a lot of vegetation rotting in it or because too much fertilizer was used in the past
...
Effects of lower pH:
• Lack of nutrients
• Poor growth of crops
• May pass onto rivers, damaging the eco-‐system within it
...
2 Types of oxides
1
...
Classification:
• Oxides are compounds composed of oxygen and another element
...
• Copper (II) oxide is called a basic oxide, since it can neutralize an acid:
o Acid + Base à Salt + Water
o CuO (s) + 2HCl (aq) —> CuCl2 (aq) + H2O (l)
• Iron (III) oxide and magnesium also behaves in a similar way -‐ they also neutralize acids, and therefore they
are basic oxides
...
• Carbon dioxide is slightly soluble in water as the solution will turn litmus paper red, which makes carbon
dioxide acidic
...
2
...
Classification:
• Some oxides of non-‐metals are neither acidic nor basic
...
• Neutral oxides neither react with acids or bases
...
3 Preparation of salts
1
...
1 and the
reactions specified in section C8
...
Preparation:
Take the acid and:
• Heat it
...
• Let the acid and the base react
...
• Evaporate water from produced during reaction
...
Separation:
• Separating a mixture is quite easy, as they are not chemically fused together
...
• The procedure to separating them are as follows:
o Add water
...
o Wait for the salt to dissolve
...
Most of the sand will be trapped in the filter, but the salt will pass through
...
o Dry it in an oven
...
Purification:
• If salt is soluble, distillation
...
• The steps in distillation:
o Gently heat the solution in the flask
...
o Vapour condenses to water in the condenser, and the water falls into a beaker through the condenser
...
Suggest a method of making a given salt from suitable starting materials, given appropriate information
...
These are:
• Metals
• Insoluble Bases
• Alkalis
• Carbonates
Metals:
•
•
•
•
•
28
We will use the reaction between Zinc with Dilute Sulfuric Acid as an example:
Metal + Acid à Hydrogen + Salt
Zinc + Sulphuric Acid à Zinc Sulphate + Hydrogen
Here are the steps to produce the salt:
1
...
2
...
3
...
4
...
This leaves you with an aqueous zinc sulfate
solution
...
Heat solution to evaporate, to arrive at crystals of zinc sulfate
...
• Metal Oxide + Acid à Salt + Water
• Iron Oxide + Sulfuric Acid –> Iron Sulfate + Water
• The processes are:
1
...
2
...
3
...
4
...
5
...
6
...
7
...
Alkali:
• An acid reacting with an alkali is known as a neutralization reaction
...
Prepare a flask
...
Add approximately 30 cm³ of sodium hydroxide into the flask
...
Add 2 drops of this indicator called phenolphthalein
...
Add the acid now
...
5
...
6
...
7
...
8
...
9
...
8
...
Use the following tests to identify:
• aqueous cations:
o ammonium, copper(II), iron(II), iron(III) and zinc by means of aqueous sodium hydroxide and aqueous
ammonia as appropriate
...
)
• anions:
o carbonate by means of dilute acid and then limewater
o chloride by means of aqueous silver nitrate under acidic conditions
o nitrate by reduction with aluminium
o sulfate by means of aqueous barium ions under acidic conditions
• gases:
o ammonia by means of damp red litmus paper
o carbon dioxide by means of limewater
o chlorine by means of damp litmus paper
o hydrogen by means of a lighted splint
29
o oxygen by means of a glowing splint
...
Copper (II)
Add dilute sodium hydroxide or
ammonia solution
...
Add dilute sodium hydroxide or
ammonia solution
...
Pale blue precipitate forms
...
Pale green precipitate forms
...
White precipitate forms
...
Anion is present if bubbles give off gas that turns
limewater milky
...
Add same amount of nitric acid
Chloride ions will form a white precipitate
...
Add silver nitrate solution
Nitrate
1
...
Nitrate ions are present if ammonia gas is given off
...
Add some pieces of aluminium
...
Add same amount of dilute
White precipitate will form if sulphate ions are present
...
2
...
Gases:
Gas
Test
What happens if gas is present?
Ammonia, NH3
Use damp red litmus paper
...
Carbon Dioxide, CO2
Bubble the gas through limewater
...
Chlorine, Cl2
Hold damp litmus paper in the gas
...
Hydrogen, H2
Put the gas in the tube and hold a
Gas burns with a squeaky pop
...
Oxygen, O2
Collect the gas in a test tube and hold a Splint relights
...
C9
...
Describe the way the Periodic Table classifies elements in order of proton number
...
• Proton number tells how many electrons there are
...
• In the periodic table atoms are arranged in atomic number order
...
Use the Periodic Table to predict properties of elements by means of groups and periods
...
30
The elements in each group have the same number of electrons in the outer orbital
...
They are the electrons involved in chemical bonds with other elements
...
Periods:
• Elements in the same period have the same number of shells on their atoms
...
• In a row across the Periodic Table, the elements get less metallic as we go from left to right
...
9
...
Describe the change from metallic to non-‐metallic character across a period
...
• Elements on the left, in Group 1, are all metallic
...
o They are less reactive
...
o They are still generally in the solid form
...
2
...
Relationship:
• The group number is closely related to the number of outer-‐shell valency electrons
...
• In Group 7, as you go down the group, the substances progress from Gas to solid
...
• In Group 1 and 2 and possibly 3, even as you move down the group, they are mostly metals
...
9
...
Describe lithium, sodium and potassium in Group I as a collection of relatively soft metals showing a trend in
melting point and reaction with water
...
• They are also soft, and can be easily cut with a knife
...
General Reactivity:
• All these elements are highly reactive
...
Difference:
• The Group 1 metals differ from other metals
...
• Li, Na and K are less dense than water which makes them float
...
• Hence, when the atom gets bigger the electrons are further from the nuclei making the attraction weaker
...
Less heat energy is needed to change the elements into their molten states
...
Reaction with Water:
• Alkali metals react with water to produce hydrogen and hydroxide
...
o The potassium melts with the heat of the reaction, and then the hydrogen catches fire
...
Predict the properties of other elements in Group I, given data where appropriate
...
• Reaction with water increases as you go down the group
...
Describe the trends in properties of chlorine, bromine and iodine in Group VII including colour, physical state
and reactions with other halide ions
...
• The elements in group VII are:
o Fluorine
o Chlorine
o Bromine
o Iodine
• Typical characteristics of halogens:
o Form colored gases: This is quite evident as fluorine is a pale yellow gas and chlorine is a green gas
...
Inhaling chlorine
gas is a one-‐way ticket to the graveyard
...
Characteristics:
Halogen
At Room Temperature:
Boiling Points / Degrees:
Fluorine
Yellow gas
-‐188
Chlorine
Green gas
-‐35
Bromine
Red liquid
59
Iodine
Black solid
184
Trends:
• Reactivity decreases as you go down the group
...
Notes:
• Boiling point increases as we go down the group
...
• Density increases
...
4
...
Properties:
• As you go down the group:
o Melting and boiling points will continue to increase
...
Density increases
Heavier
9
...
Describe the transition elements as a collection of metals having high densities, high melting points and forming
coloured compounds, and which, as elements and compounds, often act as catalysts
...
• They tend to have high melting points
...
• They often act as catalysts to speed up reactions
...
4 Noble gases
1
...
Explanation:
• Noble gases are unreactive because of their electron configuration
...
• This means that they are not in the need to losing or gaining, or even sharing electrons
...
2
...
e
...
Uses of Noble Gases:
• Noble gases might be unreactive, but they are not useless
...
• Argon:
o Due to its lack of reactivity, argon is most prominently used in lighting, e
...
for light bulbs
...
o Filling balloons
o Xenon
o Sometimes used as an anesthetic because of its high solubility in lipids
...
C10
...
1 Properties of metals
1
...
Properties of Metals:
Physical:
• Metals are solids (except Mercury)
...
• Are ductile -‐ can be drawn into wires
...
• Have a high melting points and high boiling points
...
• Good conductors of electricity and heat
...
Chemical:
•
•
33
Reaction with water and oxygen -‐ results in corrosion and rust
...
o Metals form positive ions
...
• Do not have luster -‐ they are dull
...
• Non-‐metals are brittle, so they break easily
...
• Have low density
...
• Poor conductors of heat and electricity
...
Chemical:
• Non-‐metals have 5 or more valence electrons, and therefore usually gain electrons in chemical bonds
...
2
...
Diagrams:
• Alloys is the mixture of two or more metallic elements
...
• Since the atoms are all jumbled together of different sizes, it is much more difficult for alloy layers to slide over
each other -‐ alloys are harder than pure metals
...
Explain why metals are often used in the form of alloys
...
copper/iron) are too soft for many uses
...
• An alloy has the properties of both metals -‐ it is beneficial when two metals can mix to negate the weaknesses
of each other
...
• Bronze is used for bearings and bells, and it often composed of 80% copper and 20% tin
...
10
...
Place in order of reactivity: potassium, sodium, calcium, magnesium, zinc, iron, hydrogen and copper, by reference
to the reactions, if any, of the elements with:
• water or steam
• dilute hydrochloric acid (except for alkali metals)
...
o Reactions of the metals with water or steam, and with dilute hydrochloric acid
...
Note:
• If the metals form with cold water, they form hydroxides
...
• When a metal reacts with cold water, steam, or acid – hydrogen always forms
...
Compare the reactivity series to the tendency of a metal to form its positive ion, illustrated by its reaction, if any,
with:
• the aqueous ions of other listed metals
• the oxides of the other listed metals
...
• Valence electrons are more easily lost up in the reactive series to form ionic bonds
...
Deduce an order of reactivity from a given set of experimental results
...
• The one that is likely to be most reactive, is usually the one with the most reactions to substances
...
• Controlled variables to keep:
o Time allowed for reaction to occur
o Temperature of acid
o Initial surface of metal
o Volume of acid
35
Order of Reactivity
Symbol
Potassium
Sodium
Calcium
Magnesium
Aluminium
K
Na
Ca
Mg
Al
Carbon can’t reduce
the oxides of metals
above this line
...
Hydrogen
Copper
Silver
Gold
H
Cu
Ag
Au
Most reactive
Least reactive
Element
10
...
Describe the use of carbon in the extraction of some metals from their ores
...
• An ore is a rock that contains enough of a mineral (metal compound) for the metal to be extracted from it
...
Extraction using Carbon:
• Metals such as zinc, iron and copper are present in ores as their oxides
...
• The metal oxide loses oxygen, and is therefore reduced
...
• Using iron as an example:
o iron oxide + carbon → iron + carbon dioxide
o 2Fe2O3(s) + 3C(s) → 4Fe(l) + 3CO2(g)
o The source of carbon for this reduction is coke, obtained by heating coal in the absence of oxygen
...
o Some metals, such as aluminium, are so reactive that their oxides cannot be reduced by carbon
...
Describe the essential reactions in the extraction of iron in the blast furnace
...
Coke burns in oxygen from the air, to give carbon dioxide
...
More coke reduces the carbon dioxide to carbon monoxide
...
The iron ore is reduced to iron by the carbon monoxide
...
Removing the sand: limestone breaks down to calcium oxide, a basic
CaO (s) + SiO2 (s) à CaSiO3 (s)
oxide
...
Waste Gases:
• Nitrogen – main gas in air, which has not reacted
• Carbon dioxide – from the reduction reaction in stage 3
...
Relate the method of extraction of a metal from its ore to its position in the reactivity series
...
A lot of energy is needed to reduce them to extract the metal
...
Relatively little energy is needed to reduce them to extract the metal
...
4 Uses of metals
1
...
The Use:
• Aluminium is ideal for plane manufacturing mainly due to two important factors:
o It is a lightweight metal, hence allowing the aircraft to have more lift
...
• An example of an alloy made from aluminium is: Duralumin
2
...
Galvanizing:
• Galvanizing is coating iron with zinc, so that the oxygen or water would react with zinc first
...
Sacrificial Protection:
• Sacrificial protection is like galvanization, the difference being the metal that is coated with
...
3
...
Corrosion:
• Corrosion is a process where a metal reacts with oxygen in the air to form a metal oxide
...
• The oxide layer covers the surface of the aluminium metal and prevents any further reaction (corrosion) from
happening
...
Air and water
1
...
Copper(II) sulfate test for water:
• Pure copper(II) sulfate is white -‐ also known as anhydrous copper(II) sulfate because it has no water in it
...
• It is still a dry solid, because the individual water molecules are trapped within the ionic lattice surrounding the
copper(II) ions
...
• This colour change can be used to detect the presence of water (or water vapour)
...
• This turns pink in the presence of water
...
Describe and explain, in outline, the purification of the water supply by filtration and chlorination
...
• This water might be contaminated with disease and bacteria
...
• This is done by two processes, Filtration and Chlorination
...
• The water is first passed through a filter to filter out large objects (ex
...
• Smaller particles in the water is removed by adding aluminium sulfate, which causes the smaller particles to
stick together in large pieces and settle down the filter
...
Chlorination:
• Chlorine gas is first bubbled through the water to kill the bacteria that exists in the water
...
• Water is delivered to the people that need them
...
State some of the uses of water in industry and in the home
...
Describe the separation of oxygen and nitrogen from liquid air by fractional distillation
...
1
...
2
...
This allows the gases to
boil off separately, since they all have different boiling
points
...
The gases are put into tanks or cylinders under
pressure, and sold for different uses
...
Describe the composition of clean air as being a mixture of 78% nitrogen, 21% oxygen and small quantities of
noble gases, water vapour and carbon dioxide
...
State the common air pollutants as carbon monoxide, sulfur dioxide and oxides of nitrogen, and describe their
sources
...
Sulphur Dioxide:
• Contributes to acidic rain
...
Combustion of sulphur
...
Extraction of metals from their sulfide ores
...
o This forms Sulphuric Acid (H2SO4)
o When it rains, the rain water becomes acidic
...
39
May also cause lung cancer
...
• Main source:
o In cars, the engine operates at a high temperature, giving the nitrogen and the oxygen in the air and
engine a chance to react, hence forming nitrogen monoxide
...
• Nitrogen oxide is dangerous in that it also rises in the air and mixes with rain water to form nitric acid -‐ this
can also cause acid rain
...
7
...
Oxides of Nitrogen in Car Exhausts:
• Air gets so hot inside car engines that the nitrogen and oxygen react together: (à means hot car engine)
Nitrogen + Oxygen à a mixture of nitrogen oxides
Removing the Nitrogen Oxides:
• All modern car exhausts contain catalytic converters
...
• In second part of converter – oxygen from first part oxidizes other harmful gases
...
• They are coated onto a ceramic support to give a large surface area for the reactions
...
Explain why the proportion of carbon dioxide in the atmosphere is increasing, and why this is important
...
• These warm the Earth, which reflects some of the energy again as heat
...
• But some is absorbed by greenhouse gases in the atmosphere
...
Global Warming:
• Average air temperatures around the world are rising – global warming
...
Key Greenhouse Gases:
Greenhouse Gas
Human Activities That Increase The Level
Carbon Dioxide, CO2 • Combustion of fossil fuels and other carbon-‐based fuels, in power stations, factories,
car engines, and homes
...
Methane, CH4
• Putting decaying organic matter in landfill sites; as the buried material rots, methane
forms and can escape to the air
...
Predicted Consequences:
• Ice to melt in the polar regions
...
Climate to change
...
Changes in farming
...
9
...
Pollutant
Source
Carbon Monoxide, CO
Incomplete combustion of substances
(colourless gas, no smell)
that contain carbon
– ex
...
Oxides of nitrogen
(NO, NO2, N2O – called NOx for
short, some are acidic)
Lead Compounds
The nitrogen and oxygen in air react
together inside car engines
...
Harmful Effect
-‐ Deadly: binds to the haemoglobin in
blood, and stops it carrying oxygen to
the body cells, so you can die from
oxygen starvation
...
-‐ Dissolves in rain to forb acid rain
which damages crops and forests, kills
fish, and attacks stonework and metal in
buildings
...
-‐ Some form acid rain
...
-‐ Can cause brain damage
...
Describe the formation of carbon dioxide:
• as a product of complete combustion of carbon-‐containing substances,
• as a product of respiration,
• as a product of the reaction between an acid and a carbonate,
• as a product of thermal decomposition
...
Combustion of fossil fuels – ex
...
3
...
Process that takes the place in the cells of living things, to provide energy
...
Bacteria produce carbon dioxide through respiration, using compounds from
dead remains
...
They also make a salt and water when we
neutralize them with acid
...
acid + metal carbonate → a salt + water + carbon dioxide
acid + metal hydrogen carbonate → a salt + water + carbon dioxide
Metal carbonates such as calcium carbonate break down when heated strongly -‐ called thermal
decomposition
...
When it is heated, it breaks down to form
calcium oxide and carbon dioxide
...
11
...
e
...
Ammonia:
• Ammonia (NH3) is a compound of nitrogen and hydrogen
...
• Ammonia is used to make fertilizers, explosives, dyes, household cleaners and nylon
...
• Ammonia is manufactured by combining nitrogen and hydrogen in an important industrial process called the
41
Haber process
...
• Hydrogen is obtained by reacting natural gas -‐ methane -‐ with steam, or through the cracking of oil
...
• Air is 80 per cent nitrogen; nearly all the rest is oxygen
...
• The reaction is reversible
...
Describe the rusting of iron in terms of a reaction involving air and water, and simple methods of rust prevention,
including paint and other coatings to exclude oxygen
...
• An oxidation
...
• The product is hydrated iron (III) oxide, Fe2O3
...
Ways to Prevent Rusting:
1
...
o Ex: Paint the iron or coat it with plastic or cover it with grease
...
Sacrifice another metal in place of iron
• A more reactive metal will prevent iron from rusting
...
• Without magnesium: the iron is oxidized (loses electrons)
...
Mg à Mg2+ + 2e-‐
42
o
3
...
Galvanizing
The iron is coated with a layer of zinc -‐ which is above iron in the reactivity series -‐ to give galvanized iron
...
o If the coating does get damaged, the zinc wills till protect the iron through sacrificial protection
...
Describe the need for nitrogen-‐, phosphorus-‐ and potassium-‐containing fertilizers
...
• They use these up fast, so fertilizers must be added to the soil to replace them
...
Plant
Nutrient
What it does
A fertilizer to provide it
Made by neutralizing
...
Ammonium Nitrate -‐ NH4NO3
Ammonium Sulphate -‐ (NH4)2SO4
Nitric acid with ammonia solution
Sulfuric acid with ammonia
solution
Potassium, K
Among other things, it
helps to protect plants
against disease
...
Ammonium Phosphate -‐ (NH4)3PO4 Phosphoric acid with ammonia
solution
14
...
Displacement:
• Ammonia forms when ammonium salts are heated with sodium hydroxide
...
o Ammonia is an alkaline gas, it will turn damp red litmus paper blue
...
C12
...
Describe the manufacture of sulfuric acid by the Contact process, including essential conditions
...
Describe the properties of dilute sulfuric acid as a typical acid
...
Carbonates
1
...
Carbonates:
• Carbonates are “salts” of carbonic acids (H2CO3)
...
Uses of Calcium Carbonate:
• Helping extraction of iron from its ore
...
Manufacture of Lime
• One industrial use of calcium carbonate is that it can be used to make “lime”
...
• Limestone is inserted in the kiln and then is heated
...
• Carbon dioxide is also produced
...
o This is because lime is a basic oxide, so therefore can be used to neutralize the acidity of the soil
...
o This is also because sulphur is acidic -‐ lime is a basic oxide
...
44
C14
...
1 Fuels
1
...
Fossil Fuels:
• Petroleum
• Coal
• Natural Gas
Petroleum:
• These are formed from the remains of dead organisms that fell to the ocean floor and were then buried by the
thick sediment
...
Natural Gas:
• This is composed mainly of methane and is often found with petroleum
...
Coal:
• This is the remain of lush vegetation that grew in ancient swamps
...
2
...
Understanding:
• Petroleum is a mixture of hundreds and hundreds of different hydrocarbons
...
• In order to solve this problem, we have to refine the petroleum in the process of fractional distillation
...
o Hence, they condense faster and are collected on a lower position in the fractionating column
...
Natural Gas Composition:
• Natural gas consist of 70-‐90% methane
...
4
...
Petroleum:
• A large mixture of organic compounds (hydrocarbons)
...
Process Involved:
• When you heat the petroleum, the compounds start to evaporate as particles will have more kinetic energy -‐
will more likely be able to break bonds
...
• The hot vapour rises and the vapour then condenses in the cool test tube
...
• The liquid in the first test tube is the first fraction from the distillation
...
5
...
Refinery gas:
• Used for bottled gas for heating and cooking,
Gasoline fraction:
• Used for fuel (petrol) in cars
...
14
...
Identify and draw the structures of methane, ethane, ethene and ethanol
...
Describe the concept of homologous series of alkanes and alkenes as families of compounds with similar
properties
...
• There are millions of organic chemicals, but they can be divided into groups called homologous series
...
Homologous Series – Similarities & Differences:
Similarities:
• The same general formula
...
46
• Similar chemical properties, because of this functional group
...
• Different physical properties, due to increasing molecular size
...
State the type of compound present, given a chemical name ending in -‐ane, -‐ene and -‐ol, or a molecular structure
...
• -‐ene will usually form compound alkene
...
Molecular Structure:
• Single bond -‐ alkane
• Double bond – alkene
• Oxygen -‐ alcohol
C-‐C
C=C
O-‐H
COOH
General Formula
(n = # of carbon atoms)
CnH2n+2
CnH2n
CnH2n+1OH
CnH2nO2
47
4
...
Alkanes:
Alkenes:
14
...
Describe the properties of alkanes (exemplified by methane) as being generally unreactive, except in terms of
burning
...
• The alkanes are hydrocarbons
...
• All their carbon atoms form 4 single covalent bonds
...
48
• Saturated compounds are generally unreactive
...
They burn in air
...
• Reactants: Alkane + plenty of oxygen (from air) for complete combustion (incomplete combustion with
alkane gives carbon monoxide and water)
...
• Produced: Carbon dioxide + Water + Heat
• Equation: CH4 + 202 à CO2 +2H2O
2
...
• Type of reaction: Substitution (1 or more hydrogen atoms are replaced by chlorine atoms)
...
• Required: UV light – photochemical reaction
...
State that the products of complete combustion of hydrocarbons, exemplified by methane, are carbon dioxide
and water
...
• Example:
Methane + Oxygen à Carbon Dioxide + Water
CH4 + 2O2 à CO2 + 2H2O
3
...
How are alkenes obtained?:
• Alkenes are obtained from alkanes by a process called cracking
...
• Cracking breaks down molecules into smaller ones
...
4
...
Cracking:
• Cracking is basically a process where you break down heavier molecules into lighter hydrocarbons, as there
is little industrial use for these heavy hydrocarbons
...
o High temperature is needed
o Catalyst speeds up the reaction
...
• The vapour is passed through a catalyst
...
5
...
Saturated Hydrocarbons:
• Have single C-‐C bonds between the atoms
...
49
Unsaturated Hydrocarbons:
• Have C=C double bonds
...
Molecular Structures:
• Saturated hydrocarbons have C-‐C (single bonds)
...
Reaction with aqueous bromine:
• Unlike alkanes, alkenes react with aqueous bromine (bromine water)
...
The product of the reaction is colourless, if alkenes are present
...
• Reaction occurs because of the double bond
...
• If a hydrocarbon gives a colour change from orange to colourless for bromine water, it is unsaturated
...
Get some orange solution bromine water and the suspected hydrocarbon
...
Add a few drops of bromine to the hydrocarbon
3
...
6
...
Addition Reaction:
• An addition reaction is a process where an unsaturated alkene is turned to a saturated compound
...
• The unsaturated molecule becomes saturated, and no other product is formed
...
The product of the reaction is colourless, if alkenes are present
...
• Reaction occurs because of the double bond
...
• If a hydrocarbon gives a colour change from orange to colourless for bromine water, it is unsaturated
...
• Add a few drops of bromine to the hydrocarbon
• If the solution becomes colourless, an unsaturated hydrocarbon is present
...
• (à means: add on hydrogen H2)
• Alkene à Alkane
With Steam:
• From unsaturated to saturated
...
4 Alcohols
1
...
Formation of Ethanol:
• Ethanol can be made by reacting ethene (from cracking crude oil fractions) with steam
...
o ethene + steam → ethanol
o C2H4 + H2O → C2H5OH
• Notice that ethanol is the only product
...
These features make it an efficient process, but there is a problem
...
•
•
2
...
Hydration:
• Ethene + Steam à Ethanol
• C2H4 + H2O à C2H5OH
o Reaction is reversible
...
o High pressure and low temperature would give the highest yield
...
3
...
Description:
• Ethanol burns in the air, releasing energy and producing carbon dioxide and water
...
State the uses of ethanol as a solvent and as a fuel
...
14
...
Describe macromolecules in terms of large molecules built up from small units (monomers), different
macromolecules having different units
...
• Macromolecules are sometimes also called polymers
...
• A group of many monomers stringed together will form a macromolecule
...
6 Synthetic polymers
1
...
Formation of Poly(ethene):
• A polymer is a substance that contains large molecules formed by many small molecules added together
...
• Poly-‐ means many
...
• In a polymerization reaction: thousands or smaller molecules join to form a macromolecule
...
51
2
...
3
...
• The polymerization gives long-‐chain molecules – and there is always one other product
...
14
...
Describe proteins as possessing the same (amide) linkages as nylon but formed from the linking of amino acids
...
• Like synthetic polymers, they are built up by small units joining together
...
• Proteins are an important constituent of food
...
2
...
(Structures and names
are not required
...
Hydrolysis:
• The reverse of condensation reactions that formed these compounds
...
• A process where molecules are broken down upon reaction with water
Title: IGCSE Chemistry - Exam Revision 2016
Description: Exam revision notes for the 2016 updated syllabus of "Coordinated Sciences (Double Award)". Concise and explanatory, but detailed, revision guide for chemistry in the coordinated sciences syllabus. Explains every point on the syllabus, and shows equations when needed.
Description: Exam revision notes for the 2016 updated syllabus of "Coordinated Sciences (Double Award)". Concise and explanatory, but detailed, revision guide for chemistry in the coordinated sciences syllabus. Explains every point on the syllabus, and shows equations when needed.