Transition Metals Flashcards
What shape does Ni2+ and Pt2+ complexes form
Square planar
What shape does Ag+ complexes form
Linear
Ligand definition
A molecule or ion that forms a coordinate bond with a transition metal by donating a pair of electrons
Complex definition
A central metal atom or ion surrounded by ligands
Coordination number
Number of coordinate bonds to the central metal atom or ion
Examples of multidentate ligands
EDTA^4- and porphyrin
What is a haem
Haem is an iron(II) complex with a multidentate ligand.
What is haemoglobin
Globular protein with four Fe2+ centres each with a porphyrin ligand taking up four of the six coordination sites. One of the other two is bonded to the rest of the haemoglobin leaving the last site for oxygen to bond
How does haemoglobin transport oxygen
Haem is an iron(II) complex with a multidentate ligand.
Oxygen forms a co-ordinate bond to Fe(II) in haemoglobin, enabling oxygen to be transported in the blood.
Why is carbon monoxide dangerous
Carbon monoxide is toxic because it replaces oxygen co-ordinately bonded to Fe(II) in haemoglobin.
What complexes display cis-trans isomerism
Octahedral complexes with monodentate ligands
What complexes display optical isomerism
Octahedral complexes with bidentate ligands
Label which is cis/trans isomer
Left - cis
Right - trans (across)
How do you know 🔼H is negligible
Look at the bonds being broken and made. If 6 bonds are broken in monodentate and is replaced with bidentate, then 6 bonds being made so 🔼H is negligible
What are chelating agents
Ligands that form more than one coordinate bond or many as they are very good at bonding to the metal ion and very difficult to remove.
What effects the formation of coloured ions
- metal
- the oxidation state
- the ligands
- the coordination number
The equation for the gap in energy
How to remember the effect of ph
Reduced - red ( happens in acid)
Oxidised - blue ox (happens in alkali)
It is easier to oxidise a transition metal in alkali and reduce a transition metal in acidic conditions
Tollens reagent complex
Fehling’s complex
Acidified dichromate complex
The changes of oxidation states with vanadium
Vanadium ion can be reduced in acidic conditions using zinc as the reducing agent
5+ -> 4+ -> 3+ -> 2+
YBGV
Test for vanadium oxidation states
The conditions for titration of KMnO4
Acidic conditions using dilute sulfuric acid as the acid
Why can you only use dilute sulfuric acid in titration with KMnO4
HCL cannot as MnO4- would oxidise Cl- to Cl2 - affect the volume of KMnO4 required
conc Sulfuric/nitric acid cannot - they are oxidising agents so affect the volume of KMnO4
ethanoic acid cannot - weak acid and would not provide enough H+ ions
Why do we not need an indicator for titration of KMnO4
Fe2+ and potassium manganite (VII) redox reactions
Ethanedioate ion and potassium manganite (VII) redox reactions
Heterogenous catalyst steps
- place where adsorbed are called active sites (AS)
What happens if heterogenous catalyst too strong
- reactants cannot move around surface
- products cannot desorb
- eg V and Cr are too strong so block AS
What happens when heterogenous catalyst too weak
- reactants not adsorbed
V2O5 reaction
Heterogenous catalyst example
what catalyst is used in the Haber process
Fe catalyst
3H2 +N2 <——> 2NH3
Importance of variable oxidation states
Variable oxidation states allow transition metals to act as catalysts lowering activation energy
Reaction of iodide and peroxodisulfate ions (S2O8^2-)
Why does iodide and S2O8^2- have a high activation Energy
Because both are negative ions so repel each other
Reaction of Manganate (VII) ions and ethanedioate ions
Homogenous catalyst
