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Steel Story
Describe and explain the procedure for redox titrations/with potassium manganate

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Fill burette with solution of known concentration and volume, take reading of
meniscus
Fill conical flask below with known volume of unknown concentration solution
Slowly open tap to add burette solution into conical flask, swirling flask constantly
When end point is near close tap slowly and add solution drop-wise
Usually one of products or reactants is coloured so no indicator needed
If manganate (VII) ions are in conical flask then end point is when colour disappears,
if manganate (VII) ions are in the burette then end point is when pink colour persists
for 10 seconds
After reaching end point note level of meniscus, change is the volume needed to
react
Repeat until have 3 concordant readings within 0
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Reduction is the loss of oxygen, gain of electrons or gain of hydrogen
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A reducing agent is one which donates electrons/hydrogen to or accepts oxygen from
another element/compounds (it is oxidised)
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Use systematic nomenclature to name and interpret the names of inorganic compounds

Where an element is able to have more than one oxidation state (many d-block elements),
when present in a compound its oxidation state can be represented with roman numerals
after the name, for example in copper (II) sulphide, the copper has an oxidation state of 2+
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The value of the potential difference is known as the Ecell value
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The further to the left the equilibrium lies, the more likely the electrode will donate
electrons, making it the negative electrode
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Metal-ion metal half cells occur where a strip of the metal atoms is placed in a solution of
the metal ions
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The positive electrode will be the half cell with the most positive
electrode potential – i
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the better the metal atom strip accepts electrons from solution
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g
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Explain and use the term standard electrode potential, and understand how a standard electrode potential is
measured using a hydrogen electrode

Standard Electrode Potential – the potential difference between a half cell and a hydrogen
half cell, under standard conditions
Hydrogen has been assigned the Ecell value of 0
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As temperature

and concentration/pressure can all affect electrode potential, these are standardised to 1
atmosphere, 298K and 1molar solutions
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The most positive (at the base of the series) accept
electrons the most whilst the most negative (at the top of the series) accept electrons the
least; they donate electrons most readily
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If you know the potential difference between the two cells then you can work out the
(potential) difference
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34𝑉) − (−0
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34𝑉 + 0
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10𝑉
As stated above, a redox reaction is only feasible where the Ecell value is positive
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These Ecell values allow us to make a prediction about whether a reaction will occur,
however it is important to remember that they may not actually be feasible in a half cell due
to the use of standard conditions (rate of reaction may be too slow)
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Fe2+ (aq) + 2e-  Fe(s)

-0
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40v

As the oxygen has the more positive electrode potential, the iron donates electrons to the
oxygen to become Fe2+
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Describe and explain approaches the corrosion prevention

Sacrificial protection comes in the form of galvanising or the use of zinc blocks to prevent
corrosion
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Therefore if water or oxygen come into contact with the iron, the more reactive
metal will donate electrons taken from the iron to prevent it converting into Fe 2+ ions
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Galvanizing coats the metal in a
layer of zinc which is oxidised to prevent the metal from being oxidised
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If the water lies on the barrier rather than the metal, no
electrons are drawn in the metal so it does not corrode
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Describe and explain the issues involved in the recycling of iron/steel

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Steel is magnetic and therefore can easily be sorted from other materials using low
cost magnets
All steel products can be recycled APART from aerosols
Steel is cleaned using incineration to remove labelling/paint
The composition of the steel used in recycling must be known by the steelmakers, as
some alloys make it unsuitable for certain uses e
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copper alters softness
Scrap can be added to furnaces in the production of new steel to lower the
temperature

Explain the chemical processes occurring during the extraction and purification of metals from their ores

Metals are mined and extracted via reduction
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The most unreactive
metals are found in their pure state in the Earth’s crust (gold and silver)
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The electron distribution for the D block
elements is as follows:
[Ar] 1s2 2S2 2P6 3S2 3S6

ebf

Copper and chromium both have unexpected electron configurations
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As electrons are
arranged in the lowest energy levels, minimising repulsion by keeping each electron in a
single orbital keeps the electrons at the lowest possible energy level
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When d block elements form ions, the electrons are first lost from the 4S subshell
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Where there are low ionisation enthalpies, multiple electrons are more easily lost
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In low oxidation states (such as 2+, 3+) the transition metals can exist as elements, whereas
at higher oxidation states they often form covalent bonds with highly electronegative
substances
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These weak bonds hold the
compound in place whilst the internal bonds are made and broken
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They often form an intermediate in redox reactions,
which then breaks down to give the final product
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Some of the ligands I need to know:
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Fe2+ + 6H2O → [Fe(H2O)6]2+(aq)
Fe3+ + 6H2O → [Fe(H2O)6]3+(aq)
Cu2+ + 6H2O → [Cu(H2O)6]2+(aq)

Ligand substitution is the displacement of one ligand for another, this occurs frequently with
copper ions:
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[Cu(H2O)6]2+ + 4NH3 → [Cu(NH3)4 (H2O)2]2+ + 4H2O
[Cu(H2O)6]2+ + 4Cl- → [CuCl4]2-

Use and explain the term coordination number and draw and name the shapes of complexes with
coordination numbers 4 and 6, describe the formation of complexes in terms of dative covalent bonding
between a ligand and central metal ion

Coordination number – the number of dative covalent bonds formed between ligands and
the central metal ion
A complex with the coordination number 2 will have a
linear shape, with bond angles of 180°
A complex with the coordination number 4 will have a
tetrahedral shape (can be square planar), with bond
angles of 90°

A complex with the coordination number 6 will have an octahedral shape, with bond angles
of either 90° or 120°
Explain the terms bidentate, and polydentate as applied to ligands, and outline the systematic nomenclature
of ligand naming

The number of dative covalent bonds a ligand can form with a central metal ion is
dependent on the number of lone electron pairs it possess
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g
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g
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g
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Naming ligand complexes:
1
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g
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The name of each ligand in alphabetical order e
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aqua, cyano, chloro, ammine
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The charge on the central metal ion in brackets e
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(II) for Fe2+
An example would be [Cu(NH3)4(H2O)2]2+:
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3
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4 amine/2 water molecules are bonded to each copper atom – making it tetra and di
Amine = ammine, water = aqua
Copper (has a positive charge so is written in regular English)
Copper has a charge of 2+, therefore is II
Tetraamminediaquacopper (II)

Transition metals are able to form complexes because the partially filled 3D subshells can
accept the electrons donated by the ligands

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