Revision, 3.2.9
Molecular Formula – Number of atoms in each molecule eg. C3H6
Structural Formula – Shows how the atoms are actually arranged in the molecule
H| H| H|
eg. H-C-C-C-H
| | |
HHH
Condensed Structural Formula – Simplified form of above eg. CH3CH2CH3
Branched Chain Hydrocarbons
In branched hydrocarbons, each side chain is actually an alkane molecule with one
H removed to allow it to be attached to the main chain. These side chains are called
alkyl groups.
Alkyl group
Name
- CH3
- CH2 – CH3
- CH2 – CH2 – CH3
- CH2 – CH2 – CH2 – CH3
- CH = CH2
methyl
ethyl
propyl
butyl
ethenyl
Carbon Compounds
Homologous Series
Functional Group
Prefix/Ending
Alkane
Alkene
Alkyne
Alcohol
Alkanoic acid
C–C
C=C
_
C __ C
-OH
-C=O
OH
-C=O
O - C5 or more C in a ring
Benzene ring
-Cl
-Br
-I
-F
-ane
-ene
-yne
-ol
-oic acid
Ester
Cyclic
Aromatic
Halo- (prefix to above)
Halo- (prefix to above)
Halo- (prefix to above)
Halo- (prefix to above)
C
C=C
C
C
C
C
cyclopentane
C
C
C
C
cyclohexene
-yl -oate
cyclochloro- (prefix)
bromo- (prefix)
iodo- (prefix)
fluoro- (prefix)
Ringed compounds
with alternating
double and single
bonds – really
consists of
1delocalised electrons
benzene
Nomenclature
1. Name the longest carbon chain (must include functional group if present).
Don’t forget to indicate isomers.
2. List the branches/halogens as prefixes. List alphabetically ie. bromo, chloro...
3. Number the prefix according to which C atom the branch is attached to.
Number from the end that gives the lowest numbers overall. If more than one
of a branch is attached to the same C atom, the number must be used twice
(eg. 2,2-dimethyl)
If an alkanoic acid or cyclo-?-ene, number from the functional group.
4. Add di, tri, tetra, etc as a prefix to the branch name depending on how many
times the branch appears in the molecule.
5. Use commas to separate numbers and dashes to separate prefixes.
6. Number of the functional group is sometimes written in the middle of the
name eg. ethan-1,2- diol, propan-1-ol
Isomers
Same molecular formula, different structural formula.
C = C – C – C 1-butene
C – C = C – C 2-butene
QUESTIONS
1a) Draw the structure of 2-pentanol.
b) Name the compound
2) How many compounds are there that could be named hexanol? Draw their
structures and name them.
3) Name the following compounds:
CH3
a) CH3-CH-CH-CH=CH2
CH2CH3
Br I Br
c) CH3-C-CH-CH-CH2
CH3
CH2-CH3
OH
b) CH2-CH2
OH
d) CH3-CH2-CH-CH2-COOH
CH2CH3
ACTIVITIES
 Complete Worksheet ‘Exercises’
 Complete Worksheet “Carbon Compounds”
2

1.3.2, 1.2.3
Reactivity
Alkanes don’t react much and so they aren’t useful to industry. Alkanes burn, so
they are useful as fuel.
Alkenes also burn, but they are more valuable to industry as they are highly reactive
due to their double bond. They undergo ‘addition reactions’ which involves
“opening out” of the double bond.
Saturated hydrocarbons contain only single bonds between C atoms eg. alkanes
Unsaturated hydrocarbons contain double or triple bonds between C atoms eg.
alkenes/alkynes.
Alkane or Alkene? Test using bromine water
Add bromine water (orange-brown colour).
Br2(l) + H2O(l) ⇌ HOBr(aq) + H+(aq) + Br-(aq)
If the solution discolours, the hydrocarbon was unsaturated.
Eg.
H
H
Br H
C = C(l) + HOBr(aq) + H+(aq) + Br-(aq)  H – C – C – H(l) + HBr(aq)
H
H
H OH
or
OH H
H – C – C – H(l) + HBr(aq)
H Br
3
This is an example of an addition reaction - where we break double/triple bonds
and add other atoms/groups.
If the solution only discolours in the presence of UV light, the hydrocarbon was
saturated. (UV light provides activation energy)
Eg.
H H
Br H
UV light
+
H – C – C – H(l) + HOBr(aq) + H (aq) + Br (aq)  H – C – C – H(l) + HBr(aq)
H H
H OH
Numerous variations possible
QUESTIONS
1. When propane reacts with chlorine in the presence of UV light, a great variety of
compounds is formed.
(a) How many mono-substituted compounds can be formed? Draw their structures.
(b) Write a balanced equation for the formation of one of these.
(c) How many di-substituted compounds can be formed? Draw their structures.
ACTIVITIES

EXPERIMENT – The reaction of Hexane, 1-Hexene, cyclohexane and
cyclohexene with Bromine Water. Include Title, Aim, Hypothesis, Safety,
Equipment, Variables, Method, Diagrams, Results, Discussion (include
equations and explain your results) and Conclusion.
4
Intermolecular Forces



Held together with dispersion forces.
Boiling point is an excellent indicator of the strength of dispersion forces in a
hydrocarbon.
In general,
- the higher the molecular weight the stronger the dispersion forces
- the closer the molecules pack together the stronger the dispersion forces
Industry obtains many useful products from propene and butene, but mostly from…
Ethylene (Ethene)
(Ethylene is the common name, ethene is the IUPAC (systematic) name)
5
(using ethylene as an example)
Petrol additive
Hydrogenation
H H
H–C –C–H
H H
Styrene used
to make
polystyrene
H H
Br – C – C – Br
H H
Halogenation
+ H2 with Ni
catalyst
+ Br2, Cl2 etc.
H
C=C
H
H
H
+ benzene
H
C=C
(ethenylbenzene)
H
Hydrohalogenation
CFCs used as
refrigerants, aerosol
propellants
H H
+ H2O with an
dilute acid H – C – C – OH
H H
catalyst
Hydration
H
+ HCl
H H
H – C – C – Cl
H H
Ethanol is an
important
solvent (eg.
perfumes,
medications,
varnishes etc)
+ H2O + Br2 ⇌ HOBr
H H
Br – C – C – OH
H H
Oxidation
+ ½O2 with
Ag catalyst
H2C – CH2
O
+ Cl2 + ½O2
with CuCl2
catalyst
Ethylene oxide
is a fumigant
Ethylene glycol
is used as
antifreeze and
+ H2O with an
for the
acid catalyst
production of
many polymers H H
HO – C – C – OH
H H
H
Cl
C=C
2
H
H
Vinyl chloride
is the starting
material for
PVC
6
+ H2O
QUESTIONS
1. Write equations using structural formulae for the reaction of 2-pentene with
(a) hydrogen (with a nickel catalyst)
(b) bromine in a non-aqueous solvent
(c) bromine water (bromine dissolved in water)
(d) hydrogen chloride
(e) water (with sulfuric acid catalyst)
Name the compounds formed in (a), (d) and (e).
ACTIVITIES



Complete Worksheet 1
Read 1.1
Complete Revision Questions on
p11 & 12
Names are (a) pentane (d) 3-chloropentane (e) 3-pentanol
Or if the bottom structures were used, (d) 2-chloropentane
and (e) 2-pentanol.
7
1.2.2
Current industry demands for small molecular weight hydrocarbons are more than
can be met by the fractional distillation of crude oil.
Catalytic cracking breaks high molecular weight hydrocarbons into one smaller
alkane and one smaller alkene.
Reaction conditions: Occurs on the surface of zeolites (catalyst), at 500oC, no air
and under pressure.
8
Steam cracking (or thermal cracking) is used to further decompose alkanes into
alkenes. Ethane from natural gas is heated with steam to 750oC – 900oC to produce
ethene.
QUESTIONS
1. Explain the difference between catalytic cracking and steam (or thermal)
cracking. Give equations to illustrate. What is the main purpose of each process?
ACTIVITIES


Complete worksheet ‘Production of Ethene (Ethylene)’
Read p 13 – 14
9
1.2.4, 1.2.5, 1.2.7
Ethylene is extremely valuable to industry because it can undergo polymerisation.
Polymerisation is a chemical reaction in which many small molecules (monomers)
combine to form one large molecule (polymer).
Ethylene is a monomer from which a number of polymers (plastics) can be made.
There are 2 ways of forming polymers – addition and condensation. Ethylene
forms polyethylene by addition polymerisation.
All atoms present in the monomer are also present in the polymer. Only one type of
monomer is used. Double bonds ‘open out’ to form single bonds with neighbouring
molecules.
ACTIVITY
 As a group, perform a polymerisation of ethene.
Commercially and industrially important examples of addition polymers are
polyethylene, polyvinyl chloride and polystyrene.
Polyethylene (Polythene/Polyethene)
Many CH2=CH2 (ethylene/ethene) join together to form:
- CH2 – CH2 – CH2 – CH2 – CH2 – CH2 – CH2 – CH2 – CH2 –
Abbreviated form:
-(- CH2 – CH2 -)- n
10
PVC Poly(vinyl chloride) (Poly(chloroethene))
Made from the vinyl chloride (chloroethene) monomer
H
Cl
C=C
Forms the polymer
H
H
- CH2 – CH – CH2 – CH – CH2 – CH – CH2 – CH – CH2 – CH – CH2 –
Cl
Cl
Cl
Cl
Cl
Abbreviated to:
-(- CH2 – CH -)- n
Cl
Polystyrene (Poly(ethenylbenzene))
Made from the ethenylbenzene monomer
H
C=C
H
H
Forms the polymer
=
- C6H5
- CH2 – CH – CH2 – CH – CH2 – CH – CH2 – CH – CH2 – CH – CH2 –
Abbreviated to:
-(- CH2 – CH -)-
n
11
1.2.6
1. Initiation with a peroxide initiator (radical) (R – O‧ )
2. Propagation
3. Termination
LDPE
Initiation
Propagation with chain branching (approx every 50 atoms)
Termination
HDPE
As above, but uses a Ziegler-Natta catalyst to reduce chain branching
Changing the reaction conditions changes the polymer that is produced.
12
ACTIVITIES
Read p 15 – 18 of the text book and use the information to complete the table
below.
Name
Low Density
Cross-linked
High Density
Polyethylene
Polyethylene
Polyethylene
LDPE
Abbrev.
Structure
Linear molecules
with cross-linking

Diagram
Reaction
conditions
Chemically treated
LDPE
- Example 1
of use
- Property(s)
making it
suitable for
that use
- Example 2
of use
- Property(s)
making it
suitable for
that use
13
2.2.2, 2.2.3
A small molecule is eliminated (often H2O) when monomers join together to form a
polymer. One or two types of monomers can be involved. No double bond is
involved – the bond forms from where the water molecule is eliminated.
Natural example – cellulose (one type of monomer – glucose)
Synthetic examples – nylon, polyester (2 types of monomer – an alcohol and an
ester)
14
ACTIVITIES
 Use molymod kits to construct 3 glucose molecules per group, then polymerise
them all to form cellulose.
QUESTIONS
1. The common nylon, called nylon-66, is made from
What small molecule is eliminated when these molecules polymerise? Draw a
segment of the polymer that forms; include at least two of each monomer units.
2. Kevlar is a very tough polymer; it is used for bullet-proof vests and sails for
racing yachts. It is made from H2N–C6H4–NH2 and HOOC–C6H4–COOH where
C6H4 is a benzene ring (the same ring that is present in styrene and polyester or
PET). Draw the structure of a segment of Kevlar. To which class of compound does
it belong?
3. Silicones are polymers containing Si, O, C and H. They are used as waterproofing agents, breast implants, car polishes and synthetic rubber. The simplest
silicone is made from (CH3)2Si(OH)2 (four groups attached to a central Si atom).
a) Draw the structural formula of this compound.
b) Is polymerisation of this compound addition or condensation polymerisation?
Draw a structure for a segment of the polymer to justify your choice.
15
ACTIVITIES



View polymerisation animations
Complete the Chemistry Processes and Skills question on p 18
Read the handout ‘The Chemistry of Polyethylene Production’
1.3.3
Visit the following websites to see animations of:
www.tro.org/iqm/plastic/animations.html#
Type polymerisation animation into Google (also ‘polymerization’ for the
Americans)
16
1.2.8
Different polymers have different properties which make them suitable for different
uses.
Different properties include:
 Melting/softening point
 Stability to heat and light (C-Cl bond vulnerable to UV light; some plastics,
when decomposed, release corrosive or poisonous fumes)
 Chemical stability
 Mechanical strength
 Flexibility or rigidity
 Cost
Properties depend on the structure of the polymer:
 Chain length
Long chain = high melting point, harder because more dispersion forces
 Crystallinity
- Parallel and closely packed chains (“crystalline”)  stronger and less
flexible
- Random, less closely packed chains (“amorphous”)  weaker and
softer
Drawing a polymer through a spinneret increases chain alignment and
hence crystallinity
17
 Chain branching
High chain branching = low density, low melting point, soft, flexible
 Chain stiffening (using a bigger side chain)
eg. Cl in PVC,
in polystyrene
Bigger side group = stiffer, more rigid
 Crosslinking (polymer molecules joined together eg. vulcanisation)
More crosslinking = harder, more rigid, more difficult to melt
 Additives
Pigments (colour), plasticisers (to soften), stabilisers (resistance to heat
decomposition or UV radiation), flame retardants.
 Solubility
non-polar, so insoluble in water
Relate these properties (and the reason(s) for them) to the use of a particular
polymer.
Explain how the structure and properties of polyethylene and polystyrene relate to
the way each is used. – 4 marks, HSC 2007
Refer to Table 1.7 on p 16 of your text book
ACTIVITIES



Complete Worksheet 3
Complete ‘Chemistry Processes and Skills’ handout
Complete Revision Questions on p 18 - 19
18
2.2.1
PROBLEMS with using fossil fuels for the production of polymers:
- The world will probably run out of oil in our lifetime.
- Not biodegradable (landfill problem, harms wildlife).
SOLUTIONS:
- Cost of petrol for cars will become unaffordable, but Petrochemical
(plastics) industry will be less affected as it needs much less oil.
-
Recycle – costs more than producing new plastic. Also problem of
identification (hence labelling – refer to handout ‘Some Uses For Plastics
and Recycled Plastics in Australia’)
- Develop alternative, biodegradable sources of raw materials for plastics.
Natural polymers (eg. cellulose, wool) have been in use for many centuries
and are renewable resources. Also biomass (material made by living things,
esp. plants, organic waste)
19
2.2.4, 2.2.5
Cellulose contains chains of Cs, so it’s potentially a renewable source of ethene,
propene and butene for making polymers – but there’s no simple/efficient way to
access it. Living things decompose cellulose too far to be useful. However cellulose
has been used to make other useful polymers for the last century or so.
-
Rayon (viscose rayon or viscose) – clothing
Cellophane
Cellulose nitrate (celluloid) – film, explosives
Cellulose acetate (slides)
Carboxymethyl cellulose (CMC) – food thickener
Cellulose is naturally occurring and the major component of biomass.
A condensation polymer made from the monomer glucose C6H12O6. Alternate
glucose molecules are inverted, producing a linear molecule.
HO – C6H10O4 – OH or
20
2.3.1
Biopolymer (polymer produced totally or in part by a living thing) are
biodegradable – easily broken down by bacteria. Eg. cellulose
PHAs (polyhydroxyalkanoates)
-
Made by bacterium Alcaligenes eutrophus
Similar properties to polypropylene
Biodegradable
Scientists have GM plants to produce PHAs
Most commonly known PHA is PHB (polyhydroxybutyrate or
polyhydroxybutanoate). Commercial name ‘Biopol’.
ACTIVITIES








Read p 18 – 22
Complete Revision Questions p 23
Complete Worksheet 4
Read Chemistry Processes and Skills p 23
Read the handout ‘Biopol – A Commercially Produced Biopolymer’
Read the handout ‘Current developments in the use of biopolymers’
Read the handouts ‘Investigating Biopolymers’ and the ‘New Scientist’ article.
Complete the scaffold on PHB (or ‘Biopol’)
21
⇌
H H
H – C – C – OH
H H
⇌
3.2.1, 3.2.2, 3.3.1
H
H
C=C
H
H
Ethene can be made from ethanol by dehydration:
CH3 – CH2OH  CH2 = CH2 + H2O (zeolites / conc. H2SO4 or H3PO4
catalyst + heat)
Visit http://www.starscience.net/chemistryBG/DEHYD.MOV to see an animation
of the dehydration of ethanol in conc. H2SO4 solution.
Ethanol can be made from ethene by hydration:
CH2 = CH2 + H2O  CH3 – CH2OH (dilute H2SO4 catalyst and heat)
Visit http://people.uis.edu/gtram1/organic/alkenes/hydration.gif to see an animation
of the hydration of ethene in acidic solution.
A catalyst is needed to reduce activation energy in both reactions. Water molecules
will not attack the double bond without a catalyst.
These reactions apply to all alcohols and alkenes.
3.2.3
- Used in cosmetics, food colourings and flavourings, medicines, cleaning
agents.
- Dissolves both polar and non-polar substances, so useful for getting insoluble
substances to dissolve in each other.
- Non-polar solvent since CH3 – CH2 is non-polar. Bonds by dispersion forces.
22
- Polar solvent since C – O and O – H are polar bonds. O has high
electronegativity compared to C and H. H-bonding or dipole-dipole bonding
occurs.
- Dissolves glucose, sucrose, carboxylic acids, amino acids, some proteins,
water.
QUESTIONS
1a. Draw the structure of 2-pentanol.
b. Name the compound
2. How many compounds are there that could be named hexanol? Draw their
structures and name them.
3. The compounds pentane and 1-pentanol have boiling points 138oC and 30oC.
Which boiling point belongs to which compound? Explain how you decided this.
ACTIVITIES




Read p 24 – 25 (NOT Oxidation of alcohol)
Read handout ‘Ethene to Ethanol and vice versa’ and complete questions
Use Molymod kits to model the hydration of ethene and the dehydration of
ethanol
Complete Worksheet 5
23
3.2.5, 3.2.6, 3.3.4, 3.3.5
- Up to WWII, fermentation and distillation used to obtain industrial ethanol,
after WWII, petrochemical ethene used (cheaper).
- Alcoholic drinks still use fermentation.
- Glucose broken down to ethanol and CO2 by anaerobic (no air) yeast
enzymes.
C6H12O6(aq)  2 CH3–CH2OH(aq) + 2 CO2(g)
- Up to 15% ethanol content can be produced. Above this, yeast is killed.
Higher concentrations obtained using distillation.
- Conditions for fermentation:
1.
2.
3.
4.
Grain or fruit (high starch/sugar content) mashed with water.
Yeast added.
Air excluded.
Mixture kept at approx. 37oC.
ACTIVITIES

INVESTIGATION – Mass Changes Involved in the Fermentation of Glucose.
Include Title, Aim, Hypothesis, Equipment, Safety, Diagram, Method, Results
(mass (include a graph), general obs., limewater obs., ethanol test), Discussion
(Explain – balanced equation, limewater milky? Flask lose mass?, probs and
solutions), Conclusion
Ethanol test - Test with acidified KMnO4
 100mL water
 3g yeast
 10g sucrose
Limewater
Ca(OH)2 + CO2  CaCO3(s) + H2O
24
3.2.4, 3.2.8, 3.3.2, 3.3.3
- Ethanol burns easily
- Renewable, as it can be produced by fermentation of sugar cane
- Not entirely carbon neutral – energy needed for farming, fermentation and
transport.
- Expensive to produce
ACTIVITIES




Complete Worksheet 15 – Manufacture of Ethanol
Read handouts on ethanol as a fuel
Watch ‘Lateline’ and ‘Biofuels’ videos
ASSIGNMENT:
- Summarise the use of Ethanol as an alternative car fuel
- Evaluate the success of its current usage as an alternative car fuel
25
3.2.7, 3.3.6
3 periods
Hcomb
The heat released when one mole of a fuel undergoes complete combustion at 1
atm pressure.
Just to confuse you, heat of combustion is usually written as a positive value, even
though all combustion reactions are exothermic.
Don’t forget, the equation is:


 = - m C T

comb = heat of combustion (Jmol-1)
m = mass of water heated (g)
C = specific heat capacity (J K-1 g-1)
T = final temp – initial temp (K)
NOTES: 1 mL of water = 1 g of water
You MUST specify which reactant or product you are calculating Hcomb for, since
equations can be balanced differently.
Eg.
2H2(g) + O2(g)  2H2O(g) or H2(g) + ½ O2(g)  H2O(g)
H = –572 kJ/mol of oxygen
H = –286 kJ/mol of hydrogen or water
QUESTIONS
1. 0.58g of butane was burnt with excess oxygen in a container immersed in 500mL
water at 15.3oC. After complete combustion the temperature of the water was 29oC
(after correction to constant pressure conditions). Assuming that the heat capacity
of the container is negligible compared to that of the water, calculate the heat of
combustion of butane.
26
2. Calculate the heat released per gram from the combustion of each of the
following fuels.
a) propane (Hcomb = 2220 kJ/mol)
b) octane (Hcomb = 5460 kJ/mol)
c) ethyne (Hcomb = 1300 kJ/mol)
3. What mass of ethanol do you need to burn to boil enough water to make a cup of
coffee? Assume that you need 250 g water of specific heat capacity 4.2 J K–1 g–1,
that it needs to be heated from 20oC to 100oC, that the molar heat capacity of
ethanol is 1360 kJ mol–1, and that 50% of the heat is lost to the surroundings.
ACTIVITIES






EXPERIMENT – Worksheet 11 - Heat of combustion of ethanol and other
alcohols. Include in your report Title, Aim, Hypothesis (SI data book),
Equipment list, Safety, Variables, Method, Diagram, Results (Table with
measurements, calculate H per gram AND per mole), Discussion (Validity,
Accuracy, Reliability, Explanation), Conclusion
Complete Worksheet 6
Complete ‘Ethanol as a Fuel’ worksheet
Read p 26 – 29
Complete Revision Questions p 30
Complete Exam-style Questions p34 - 36
27
4.2.1, 4.2.2, 4.2.3
- Important for:
 Corrosion protection
 Batteries
 Production and refining of metals
 Electroplating
ACTIVITIES
 Complete ‘Assumed knowledge’ worksheet
 EXPERIMENT – Cu and Zn Displacement Reaction
A more active metal will displace a less active metal from solution.
ACTIVITY SERIES
K > Na > Li > Ba > Ca > Mg > Al > Zn > Cr > Fe > Ni > Sn > Pb > H > Cu > Ag >
Hg > Pt > Au
More active
Metals on the left of the series are more active than those on the right.
Less active
Many elements, esp. transition metals, have variable valencies.
An approximation to this series can be found as the list of Standard Reduction
Potentials on the back of the data sheet. Also includes non-metals.
In a displacement reaction:
- one metal loses electrons
- one metal gains those electrons
- Called ‘redox reactions’ or ‘electron transfer reactions’
- Oxidation – loss of electrons
- Reduction – gain of electrons
- Use half equations:
Eg. Cu(s) + 2Ag+(aq)  2Ag(s) + Cu2+(aq)
Red Ag+ + e-  Ag
Ox
Cu  Cu2+ + 2e28
O oxidation
I is
L loss of eR reduction
I is
G gain of e-
Half equations are balanced separately. Make sure the overall equation is properly
balanced if you add two half equations together.
Use Roman numerals in brackets or compound formula to determine oxidation
state. The oxidation state of any element if it is in elemental form is 0.
Ions in the solution that do not gain or lose electrons (don’t change valency) are
spectator ions.
A chemical that causes oxidation of another chemical is an oxidant (oxidising
agent).
A chemical that causes reduction of another chemical is a reductant (reducing
agent).
OXIDATION STATES
Oxidation states are simply the valency of an atom. For elements, the oxidation
state is always 0, no matter what state the element is in. For compounds, you need
to work it out based on what the formula is. Groups I and II always have oxidation
state +1 and +2 respectively. However, the transition metals and non-metals
(sometimes) can vary. Use the other atoms in the formula to work out the unknown.
Assume H is always +1 and O is always -2.
Remember, a redox reaction only occurs if there is a change in oxidation states (ie.
electrons are lost and gained in the reaction).
Balancing RedOx equations
When you balance a redox equation you need to ensure not only that the number of
atoms balance, but also that the number of electrons balance.
1. Write each half equation from the list on the back of the Periodic Table, with
the  above each other (for clarity)
2. Multiply each equation through by a whole number so the number of electrons
is the same in both half equations.
3. Add the two equations. Don’t write the electrons.
4. Double check the whole equation balances.
29
QUESTIONS
1. In each of the following compounds, calculate the oxidation number of
phosphorus: PH3, P4, PF3, H3PO3, P2O5, H3PO4
2. Balance the following redox equations.
a. Cr2O72- + I- ⇌Cr3+ + I2
b. Al + ½O2 + H2O ⇌ Al3+ + 2OH-
c. Ba + SO42- + 4H+ ⇌ SO2 + 2H2O + Ba2+
d. ½H2 + OH- + ½Cl2 ⇌ H2O + ClACTIVITIES




Complete ‘Oxidation/Reduction’ worksheet
Read p 38 - 42
Complete ‘Simple Redox Reactions’ q 1 – 13 on Worksheet
Complete Worksheet 10
30
4.2.4, 4.2.5, 4.2.6, 4.3.1
We can make redox reactions generate electricity by using a galvanic cell (or
voltaic cell).
- Electrodes are the two different metals.
- Electrolyte is the solution/molten substance that conducts electricity.
- Salt bridge allows migration of ions to equalise the charge and keep electrons
flowing. KNO3 is used because no precipitates formed.
- Car batteries, dry cells (eg. AA, AAA, C, D batteries and watch batteries) are
galvanic cells.
- Reaction will continue until equilibrium is reached when Voltage drops to 0V.
- Oxidation happens at the anode
(negative electrode – place of e- generation)
- Reduction happens at the cathode
(positive electrode – place of e- acceptance)
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- Shorthand way of representing cell diagrams:
anode
Eg.
electrolyte
cathode
Cu(s) | Cu2+(aq) || Ag+(aq) | Ag(s)
salt bridge
…means a copper wire dips into a solution of Cu ions, connected by a salt bridge to
a solution of silver ions containing a silver wire.
- An inert Pt or C electrode is usually used if one of the substances is a gas or a
liquid, or aqueous.
Eg. Ag(s) | Ag+(aq) || Cl-(aq) | Cl2(g), Pt(s)
- Hg and Br are liquids
Eg. Ag(s) | Ag+(aq) || Br-(aq), Br2(l) | Pt(s)
QUESTIONS
1. Write the following cells using the shorthand method:
a. A zinc electrode is placed into a solution of zinc sulfate, connected by a salt
bridge to a solution of iron (II) nitrate with an iron electrode.
b. An iron wire is placed into a solution of iron (III) nitrate, connected by a
salt bridge to a solution of mercury (I) nitrate and liquid mercury with a
platinum electrode.
ACTIVITIES
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EXPERIMENT – Galvanic cells
Read p 44 – 48
Complete Revision Questions p 48
Complete ‘Galvanic Cells’ q 14 – 19 Worksheet
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4.3.2, 4.3.3, 4.3.4
- Electromotive Force (EMF) is the potential difference (voltage) across the
electrodes.
- All possible cells have been measured for EMF against a standard hydrogen
electrode (reference electrode) consisting of:
- 1M H+
- H2(g) at 1atm
- Pt electrode
- This gives us ‘Standard Electrode Potentials’ (Eo) or
‘Standard Reduction Potentials’. All are reduction
reactions ONLY. See back of data sheet.
- If the conditions are NOT standard, it is just called
electrode potential.
- (Oxidation potential) = – (Standard reduction potential)
QUESTIONS
1. Draw the cell used to determine the standard electrode for Ni2+.
2. Draw a cell showing Ag(s) | Ag+(aq) || Br-(aq), Br2(l) | Pt(s)
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EMF(total) = EMF(red) + EMF(ox)
-
Write the half equations first.
Remember (Oxidation potential) = – (Standard reduction potential)
+ EMF(total) means reaction occurs as written.
- EMF(total) means reaction occurs in reverse.
Different balancing on half equations does not alter Eo
QUESTIONS
ACTIVITIES
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Complete Cell EMFs and Electrode Potentials q 20 – 30
Complete Worksheet 12
EXPERIMENT – Worksheet 11
ASSIGNMENT – Evaluation of cells
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5.2.1
- Radioactive isotopes (radioisotopes) emit radioactivity.
- All isotopes of some elements are radioactive, while only some isotopes of
other elements are radioactive. Depends upon:
 Atomic no > 83
 Ratio of protons to neutrons
A
- A = Mass no
= No protons + No neutrons
Z
- Z = Atomic no = No protons
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M
Types of radioactivity:
Penetrating Charge
ability
 emission – 2 protons and 2 neutrons ejected (He nucleus)
- Nuclear equation for  emission:
U  4He +
238
92
2
234
Th
90
 emission – neutron  proton + electron
- Nuclear equation for  emission:
Co  0e- +
60
27
-1
60
Ni
28
Could also emit a positron (positive electron) which is a form of antimatter.
 emission – usually emitted with  or  EM radiation, not a particle.
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Decay Chain – The consecutive radioactive decay processes an atom will undergo
until it becomes a stable isotope. Can include  and  decay.
Half-life – time for ½ atoms of one radioisotope to radioactively decay into a
different atom.
ACTIVITIES
 Read p 56 - 58
 Complete Worksheet 13
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5.2.4
Detecting radioactivity depends upon its properties. Alpha and beta are charged.
- Photographic film – exposed (radiation badges) Degree of darkening of film
indicates length and intensity of exposure.
- Cloud chamber – ionising ability, visualise path of radioactivity.
- Geiger-Muller counter – uses ionising ability of radioactivity to detect amount
- Scintillation counter – some substances (eg. zinc sulfide) emit light when
struck by radioactivity. Light flashes are counted electronically.
Radioactivity is measured in Sieverts (Sv), Becquerel (Bq) or Curie (Ci)
ACTIVITIES
 Read p 60 – 61
 Complete Revision Questions p 61 – 62
 Read ‘Detecting radiation’
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5.2.2, 5.3.1
Transmutation – the change of one element into another.
Artificially produced radioisotopes can be produced by:
- Bombardment with charged particles, such as the nuclei of other elements.
Must be accelerated to high velocities to overcome electrostatic repulsion.
Linear accelerators, cyclotrons and synchrotrons are the 3 types of particle
accelerators used to accelerate particles to high velocities. Cyclotrons used for
production of medical isotopes eg. Tc-99m
- Neutron bombardment in nuclear reactor. No electrostatic repulsion to be
overcome.
Transuranic elements
- Elements with atomic no > 92.
- Made as above
- Decay extremely rapidly – little known of their physical/chemical properties.
ACTIVITIES
 Read ‘Transuranic elements and their production’
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5.2.3, 5.2.5, 5.2.6, 5.3.2
There are many medical and industrial uses of radioisotopes. Whether a
radioisotope is useful for a particular purpose depends upon it properties, including:
- radioactivity emitted ,  or 
- penetrating ability
- ionisation ability
- half-life
- biological labelling ability (whether it is used by different parts of the body)
ACTIVITIES
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Read p Read p 62 – 65
Complete ‘Chemistry Processes and Skills Part 1’ on p 65 – 66
Complete Worksheet 14
Complete ‘Uses of Radioisotopes’ worksheet
ASSIGNMENT – Nuclear Research
Complete Revision Questions on p 66
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