Transisition Metals Flashcards
What colour ppt does Cu2+ form with hydroxide or nh3
Pale blue solution to blue ppt
What colour does fe 2+ when it reacts with a hydroxide or nh3
Pale green solution to green ppt
What colour does fe 3+ go when it reacts with hydroxide or nh3
Yellow solution to orange ppt
What colour does Mn go when it reacts with hydroxide or nh3
Pale pink solution to pink ppt
What colour does cr 3+ go when it reacts with hydroxide or nh3
Green solution to grey green ppt
What forms with [Cu(H2O)6]2+ and excess nh3
Reacts further from [Cu(OH)2(H2O)4] to [Cu(NH3)4(H2O)2]
Dark blue ppt
What happens when [cr(h2o)6]3+ reacts with excess NaOH
Forms [Cr(OH)6]3-
Dark green
What happens when [cr(h2o)6]3+ reacts with excess nh3
Forms [Cr(nh3)6]3+
Purple colour
Define transition element
D block element
Can form at least 1 stable ion
With an incomplete sub shell
What is the electron configuration of Cr
3d5 4s1
What is the electron configuration of Cu
3d10 4s1
Why isn’t sc a transition metal
Only forms 1 stable ion: Sc3+
But it has an empty d sub shell
Why isn’t Zn a transition metal
Only forms 1 stable ion: Zn2+
Looses both electrons from the 4s
So has a complete d sub shell
What does Cuso4 catalyse
Zn + acids
What does mno2 catalyse
Decomposition of h2o2
What does fe catalyse
The haver process
Why do transition elements make good catalysts
Change ox states easily by gaining or losing electrons from their d orbitals
So the transfer of electrons speeds up the rate of reaction
Good at adsorbing substances onto their surfaces to lower their activation energy
What is the risk of using transition metals as catalysts
They are toxic
Cu = liver and kidney damage
Mn = physiatric problems
Define complex ion
Metal ion surrounded by coordinately bonded ligands
What is a coordinate bond
When both electrons in a shared pair come from 1 atom
What is a ligand
Atom/ion/molecule that donates a pair of electrons to a central metal ion
What is the coordination number
The number of coordinate bonds attached to the central metal ion
What is a monodentate Ligand
One lone pair available for bonding
What is a ligand with 2 lone pairs available for bonding
Bidentate
What type of isomerism do complex ions show
Cis/trans and optical
What shape is cis platin
Square planar
How is cis platin an anti cancer drug
Cl are displaced
pt bonds to 2 N atoms on the cancer cells dna
Blocks the translation and transcription of dna
Cell can’t divide
Cell dies
Why is cis platin bad
Prevents division of normal cells
Suppresses immune system increasing risk of infection
Kidney damage
What type of reaction do complex ions undergo
Ligand substitution
What happens when the ligands substitution uses similar size Ligands
Same coord no
Same shape
What is the colour change in the reaction and write an equation:
Cr(h2o)6]3+ + 6nh3
-> cr(nh3)6]3+ + 6h2o
Violet -> purple
What happens in ligand substitution when the Lignads are different sizes
Change coord no
Change shape
Give the equation and colour change and change in shape of this reaction
Cu(H2O)6]2+ + 4cl-
-> cu(Cl)4]2- + 6h20
Pale blue -> yellow
Octahedral-> tetrahedral
Give the equation and colour change of the reaction:
Cu(H2O)6]2+ + 4nh3
Why does nh3 have to be in excess
Cu(nh3)4(H2O)2]2+ + 4h2o
Pale blue to deep blue
You get a hydroxide ppt
How many coordinate bonds does haemoglobin have
6
How many lone pairs does the haem group give
4
How many lone pairs does the globin group give
1
Apart from N what else is bonded to the fe in haemolglobin
H2O
What happens to haemoglobin in the lungs
High o2 conc
Water replaced by o2
Forms ocyhaemoglobin
Transported around the rest of the body
Why is CO so dangerous
Co swaps with H2O ans binds to the fe
Forms carboxyhaemoglobin
Co is a strong ligand and won’t swap back with o2
So o2 isn’t transported around the body
How is fe2+ oxidised to fe3+
Acidified KMnO4
What is the colour change from fe2+ to fe3+
Pale green -> yellow
What is the half equation for KMnO4 as an oxidising agent
MnO4- + 8H+ + 5e- -> Mn2+ + 4H2o
What is the half equation of the oxidation of fe2+ to fe3+
Fe2+ -> fe3+ + e-
How is fe3+ reduced to fe2+
What is the colour change
I- ions
Yellow -> pale green
What is the half equations for the reduction of fe3+ using I-
2I- -> I2 + 2e-
Fe3+ + 3- -> Fe2+
How is the cr3+ ion in cr(oh)6]3- oxidised to cro4)2- solution
Warm with hydrogen peroxide
H202
In alkaline solutions
What is the half equations for the intro conversion between cr3+ to cro42-
H2o2 + 2e- -> 2Oh-
2cr(oh)6]3- + 4OH- -> 2Cro4)2- + 8H2o + 6e-
What is the eqauition to produce the orange cr2o7)2-
2CrO4)2- + 2H+ -> cr2o7)2- + h29
H+ comes from dilute sulfuric acid
How is cr2o7)2- reduced to cr3+
And what is the colour change
Organe to green
Add acidified Zn
What are the half equation for the reduction to cr3+ using Zn
Zn -> zn2+ + 2e-
Cr2O7)2- + 14H+6e- -> 2Cr3+ + 7h2o
How is cu2+ reduced to Cu+
What is the colour change
I- ions
Pale b,he -> off white ppt
What is the eqauition for the reduction of cu2+ to Cu+
2cu2+ + 4i- -> 2cui + i2
Why does Cu+ spontaneously disproportionates
It’s unstable
What is the reaction of Cu+ disproportionatation
2cu+ -> Cu + cu2+
What ode spontaneous disproportion mean
The species oxidises ans reduced itself
