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  • Created by: Gemma
  • Created on: 11-04-14 14:58
Definition of a ligand
A negatively charged ion/neutral molecule with a lone pair of electrons
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Colour of Zn (s) and Ag (s)
grey
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Colour of Cu2+ (aq)
blue solution
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Colour of Zn (aq) & Ag (aq)
colourless
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Colour of Cu (s)
orange
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Why is a platinum electrode used in some half cells?
When different oxidation states of the same element in an aqueous solution are present - when there's no metal
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Define standard electrode potential
The potential difference between a metal ion/metal half cell and the standard hydrogen half cell
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Which way do the electrons flow in en electrochemical cell?
From the anode to the cathode (- to +)
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How do you Calculate the standard electrode potential of the electrochemical cell (E cell)
s.e.p of the most positive - s.e.p. of the least positive
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Standard conditions for the half cell
1 atm, 1 mol dm-3 , 298K
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Why might a reaction not happen at standard conditions, even though it may theoretically be feasible?
rate of reaction might be very slow
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What can be done to make sure the reaction occurs /is feasible + problem?
Could use a catalyst - this will speed up the rate of reaction, but the electrode potential value will change as it is not under standard conditions
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In the process of rusting , what happens to the oxygen + where does it occur?
Oxygen is reduced to OH- , at the side of the water drop
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In the process of rusting, what happens to the iron + where does it occur?
Iron becomes oxidised to Fe2+ , this happens at the centre of the drop
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Where does the rust form?
at the sides of the water drop
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Where is the iron eaten away in rusting?
the middle - it is being oxidised
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What increases the process of rusting?
The presence of salt (NaCl) - increases the conductivity of the water , so it occurs more quickly. Also acidic conditions speed up the reaction
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What is the formula of rust?
Fe2O3*xH2O
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What is the definition of a transition metal?
a d block element which can form one/more stable ion with a partially filled d sub shell
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Colour of Fe2+
green
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Colour of Fe3+
yellow
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Colour of Cu2+
blue
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Reaction of Cu2+ and OH- + colour
Cu2+ + (OH)2 ==> Cu(OH)2 blue solution
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Reaction of Fe2+ and OH- + colour
Fe2+ + (OH)2 ==> Fe(OH)2 green gelatinous precipitate
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Reaction of Fe3+ and OH- + colour
Fe3+ + (OH)3 ==> Fe(OH)3 orange gelatinous precipitate
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Colour of [Cu(H2O)6]2-
blue
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Colour of [CuCl4]2-
yellow
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Colour of [Cu(NH3)4 (H2O)2] 2-
deep blue/violet
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Why are copper + chromium arranged in the way they are?
To arrange themself so a lower energy level is required
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Definition of monodentate + example
when ligands can only bond to a metal ion through a single atom/ion e.g. H2O/NH3
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Definition of bidentate + example
ligands can form 2 bonds with a metal ion (using pairs of electrons from 2 oxygen /nitrogen atoms) e.g. ethanedioate ion
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Definition of polydentate + example
ligands can bond through more than one atom e.g. EDTA
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Why TM can act as homogeneous catalyst?
TM have various oxidation states which can form intermediate compounds
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Why TM can act as heterogeneous catalysts?
Their ability to use electrons from 3D + 4S sub shell to form weak bonds with the reactants
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Other cards in this set

Card 2

Front

Colour of Zn (s) and Ag (s)

Back

grey

Card 3

Front

Colour of Cu2+ (aq)

Back

Preview of the front of card 3

Card 4

Front

Colour of Zn (aq) & Ag (aq)

Back

Preview of the front of card 4

Card 5

Front

Colour of Cu (s)

Back

Preview of the front of card 5
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