Unit 3.5.4 - Transition Metals Flashcards
What catalyst is used in the haber process?
Iron
Name three unidentate ligands.
Ammonia, chloride ions and water
What formal can be used to find the amount of energy absorbed when electrons jump between states in the d subshell?
∆E = hv
What is the shape and bond angle for complex ions with the coordination number of 4?
Tetrahedral - 109.5
What is the equation for what is happening in catalytic converters?
2CO + 2NO → 2CO₂ + N
Draw what [Cu(Cl)4]2- looks like.
What do you have to produce before you can do spectrometry to find the concentration of a complex ion in a solution? And how? And Why?
A calibration graph - by measuring absorbances of known concentrations of solution and plotting a graph - so you can measure the absorbance of the sample off the graph to find its concentraion
Why is there two energy levels within the 3d subshell in complex ions?
When a ligand bonds to the metal ion some orbitals are give more than others splitting the energy level in two
Draw what Tollen’s reagent looks like.
What is the lowest energy level within the 3d subshell called?
Ground state
What is meant by coordination number?
The number of coordinate bonds that are formed with the central metal ions
What is the intermediate species in between S₂O₈²⁻ and I⁻ ?
Fe³⁺
What is the intermediate species in the reaction between MnO₄⁻ and C₂O₄²⁻?
Mn³⁺
Name two ways you can maximise the efficiency and minimise the costs of an expensive catalyst.
1.) increase their surface area 2.) remove catalyst poisons from the reactants
What colour is [Co(H₂O)₄(OH)₂]?
Blue precipitate
What is the general equation for the reaction between an aldehyde and Tollen’s reagent?
RCHO + 2[Ag(NH₃)₂]⁺ 3OH⁻ → RCOO⁻ + 2Ag + 4NH₃ + 2H₂O
What colour is the Cr²⁺ ion?
Blue
What is a complex ion?
A metal ion surrounded by co-ordinately bonded ligands
What is a unidentate ligand?
Ligands that only form one coordinate bond
What colour is the CrO₄²⁻ ion?
Yellow
What is haemoglobin called when it has an oxygen ligand?
Oxyhaemoglobin
Name a biological complex ion.
Haemoglobin
What is the vanadium ion with the oxidation state +3?
V³⁺
Draw what 1,2-diaminoethane looks like.
Why are transition metals far to the right of period 5 and 6 not good catalysts?
They absorb reactants too weakly
What is the usual coordination number when metal ions are bonded to smaller ligands?
6
What do aldehydes and ketones produced when reacted with Tollen’s reagent?
Aldehydes - silver mirror Ketones - no visible change
What can poison the catalyst in the haber process?
Sulphur
What catalyst is use during the manufacturing of methanol?
Chromium (III) oxide - Cr₂O₃
What happens if you add H⁺ ions to this reaction : Cr₂O₇²⁻ + H₂O ⇋ 2CrO₄²⁻ + 2H⁺ ?
The increased concentration of H⁺ ions moves the position of equilibrium to the left producing more Cr₂O₇²⁻ ions
What is catalyst poisoning?
Where impurities bind to the catalysts surface and block reactants from being absorbed
What does h and v stand for in: ∆E = hv?
v - frequency of light absorbed in Hz h - planck’s constant
Name a multidentate ligand and how many bonds it forms.
EDTA⁴⁻ - it forms 6 bonds
When oxidised Co²⁺ to Co³⁺ why is the method of using ammonia used more often?
It is easier to oxidised [Co(NH₃)₆]²⁺ than [Co(H₂O)₆]²⁺
What colour is the Fe³⁺ ion?
Yellow
What is the initial equation for what is happening when MnO₄⁻ reacts with C₂O₄²⁻ ?
2MnO₄⁻ + 16H⁺ + 5C₂O₄²⁻→ 2Mn²⁺ + 8H₂O + 10CO₂
What colour is the end point of the titration between Fe²⁺ and MnO₄⁻?
Purple
What is the equation for the titration off Fe²⁺ against MnO₄⁻?
MnO₄⁻ + 8H⁺ + 5Fe²⁺→ Mn²⁺ + 4H₂O + 5Fe³⁺
What is the overall equation for what methanol is manufacture from carbon monoxide and hydrogen?
CO + 2H₂ → CH₃OH
What can you use spectrometry of a solution containing a complex ion to find?
The concentration of the solution
Why does a reaction speed up increasing if autocatalysis is taking place?
As the reaction progresses the amount of product increases there is more catalyst and so the reaction speeds up over time
How does haemoglobin transport oxygen around the body?
In the lungs where oxygen concentration is high its water ligand is substituted for an oxygen ligand In the respiring cells where the oxygen concentration is low its oxygen ligand is substituted for a water ligand
Why are transition metals far to the left of period 5 and 6 not good catalysts?
They absorb the reactants too strongly
How do homogeneous catalysts work in two steps?
1.) The reactant combines with the catalyst to form an intermediate species 2.) The intermediate species than reacts with the other reactants to form the products and catalyst faster than the original reactants would off
How can you turn Cr₂O₇²⁻ into CrO₄²⁻ ions?
Putting it into alkali solution - OH⁻ ions
What are the there steps to change [Co(H₂O)₆]²⁺ to [Co(NH₃)₆]³⁺?
1.) add a small amount of NH₃ to the solution to form [Co(H₂O)₄(OH)₂] 2.) add excess NH₃ to the solution to form [Co(NH₃)₆]²⁺ 3.) leave to stand in air so it is oxidised to [Co(NH₃)₆]³⁺
What is the colour change in this reaction: 2Cr³⁺ + 10OH⁻ + 3H₂O₂ → 2CrO₄²⁻ + 8H₂O?
Green to Yellow
What is the overall reaction for what is happening during the contact process?
SO₂ + 1/2O₂ → SO₃
Name a silver complex with the shape linear. And give its common name.
[Ag(NH₃)₂]⁺ - Tollen’s reagent
Draw what [Fe(H2O)6]2+ looks like.
What is cisplatin? And what does it look like?
A platinium (II) complex, it has two ammonia ligands and two chloride ligands
What does a haemoglobin complex ion look like?
A central Fe²⁺ ions which is hexa-coordinated to four nitrogen atoms, a global molecule and either an oxygen or water molecule
Why doesn’t chromium follow the usual rules for electronic configuration?
Chromium prefers to have one electron in each orbital of the 3d subshell and just one in the 4s subshell
Why is cisplatin used as an anticancer drug?
It forms coordinate bonds with nitrogen atoms in the DNA, preventing it from unwinding and so replicating, meaning the cancer cells can’t replicate
What is the usual coordination number when metal ions are bonded to larger ligands?
4
What are the two types of catalysts?
Heterogeneous and homogenous
How do you form Cr³⁺ from Cr₂O₇²⁻ ions?
Cr₂O₇²⁻ is reduced by Zn in acidic conditions
Where is the d block in the periodic table? And what type of elements make it up?
The middle - Transition metals
Name four processes where heterogeneous catalysts are use.
Catalytic converters, contact process, manufacturing of methanol and the haber process
What is the highest energy level within the 3d subshell called?
Excited state
What is the vanadium ion with the oxidation state +2?
V²⁺
What is autocatalysis?
Where the products of the recantation catalyse the reaction
What is a downside to cisplatin?
It prevents normal cells like blood and hair cells from replicating
Why do some transition metals have variable oxidation states?
The energy levels of 4s and 3d subshells are very close together so different number of electrons can be lost using a fairly similar amount of energy
What is the overall equation for reaction between S₂O₈²⁻ and I⁻ ions?
S₂O₈²⁻ + 2I⁻→ I₂ + 2SO₄²⁻
What colour is the Cr³⁺ ion?
Violet
What is multidentate ligand?
Ligands that form more than two coordinate bonds
Draw what EDTA4- looks like
What is the shape and bond angle for complex ions with the coordination number of 2?
Linear - 180
What is a catalyst?
Something that speeds up the rate of reaction without being used up or changed
What is the contact process used to make?
Sulphuric acid
Which electrons are removed first when transition metals become positive ions?
S and then d
What is the manganese ion with the oxidation state +2?
Mn²⁺
What is the colour of the V²⁺ ion?
Violet
How do you form Cr²⁺ ions from Cr³⁺ ions?
Cr³⁺ is reduced by Zn in acidic conditions
What is the vanadium ion with the oxidation state +4?
VO²⁺
What are the two equations in the reaction between S₂O₈²⁻ and I⁻ ions when there is an Fe²⁺ catalyst?
1.) S₂O₈²⁻ + 2Fe²⁺ → 2Fe³⁺ + 2SO₄²⁻ 2.) 2Fe³⁺ + 2I⁻ → I₂ + 2Fe²⁺
What two oxidising agents do you have to know about the titration with Fe²⁺?
Cr₂O₇²⁻ ions and MnO₄⁻
Why isn’t scandium a transition metal?
The only ion it forms, Sc³⁺ has an empty d subshell
What four factors affect the amount of energy needed to make electrons jump and so the colour of the complexes?
Central metal ion, oxidation state, the ligands and the coordination number
Do transition metals have similar or different chemical and physical properties?
Similar
What is the colour change in this reaction: Cr₂O₇²⁻ + 14H⁺ + 3Zn → 3Zn²⁺ + 2Cr³⁺+ 7H₂O?
Orange to green
How many coordinate bonds do silver complexes tend to make?
2
Where does the sulphur that poison the iron catalyst in the haber process come from?
Hydrogen used in the process comes from methane which contains sulphur impurities
Which two transition metals don’t follow the usually rules for electronic configuration?
Chromium and copper
What is the equation for the oxidation of Co²⁺ to Co³⁺ by hydrogen peroxide in alkaline solution?
2Co²⁺ + H₂O₂ + 2H⁺ → 2Co³⁺ + 2H₂O
What does the shape of a complex ion depend upon?
Its coordination number
What three oxidation states can chromium exist as?
+2, +3 and +6
What colour is the end point of the titration between Fe²⁺ and Cr₂O₇²⁻?
Orange
What is the equation of the oxidation of Cr³⁺ to CrO₄²⁻ by hydrogen peroxide in alkaline solution?
2Cr³⁺ + 10OH⁻ + 3H₂O₂ → 2CrO₄²⁻ + 8H₂O
What is Tollen’s reagent used for?
To distinguish between aldehydes and ketones
What happens if you add OH⁻ ions to this reaction : Cr₂O₇²⁻ + H₂O ⇋ 2CrO₄²⁻ + 2H⁺ ?
When OH⁻ ions are added H⁺ ions are removed decreasing their concentraion moving the position of equilbrium to the right producing more CrO₄²⁻ ions
What can poison catalytic converters? And where is it from? And Why?
Lead from the petrol coats the surface of the lattice
What is a bidentate ligand?
Ligands that from two coordinate bonds
What is the main feature of transition metals that cause their special chemical properties?
Incomplete d subshell
What colour is the Mn²⁺ ion?
Pale pink
What is the function of haemoglobin?
To transport oxygen around the body
What colour is [Co(NH₃)₆]²⁺?
Straw coloured solution
What colour is [Co(NH₃)₆]³⁺?
Dark brown solution
What catalyst is used in the reaction between MnO₄⁻ and C₂O₄²⁻ ions
Mn²⁺
What is the haber process?
Where ammonia is made from nitrogen and hydrogen
How do catalysts speed up the rate of reaction?
By providing an alternative pathway that requires less activation energy
Why does water only form one coordinate bond even though it has two lone pairs of electrons?
The lone pairs are so close it is only possible to form one
Why does sulphur cause catalyst poisoning in the haber process?
It is absorbed onto the iron catalyst forming iron sulphide and stopping the reactants from binding to it
What is an example of an autocatalysis reaction?
The reaction between manganate (VII) ions (MnO₄⁻) and ethandioate ions (C₂O₄²⁻)
How many steps are there in the contact process?
Two
What is methanol manufactured from?
Carbon monoxide and hydrogen
What is the equation for the reduction of Cr₂O₇²⁻ into Cr³⁺ by zinc in acidic conditions?
Cr₂O₇²⁻ + 14H⁺ + 3Zn → 3Zn²⁺ + 2Cr³⁺+ 7H₂O
What is the colour of the VO²⁺ ion?
Blue
What colour is the Ni²⁺ ion?
Green
Name two smaller ligands.
Water and ammonia
What is the equation of the reduction of Cr³⁺ to Cr²⁺ by zinc in acidic conditions?
2Cr³⁺ + Zn → Zn²⁺ + 2Cr²⁺
What colour is the Co²⁺ ion?
Pink
Why does catalyst poisoning reduce the rate of reaction?
The catalysts have a reduced surface area reaching the rate of reaction
What is a homogenous catalyst?
One that is the same physical state as the reactants
What must ligands have? And why?
At least one lone pair of electrons - otherwise it won’t have anything to form a coordinate bond
Name two bidentate ligands
1,2-diaminoethane and ethandioate ion
What five things does carbon monoxide poisoning cause?
1.) Starves the organs of oxygen 2.) Head aches 3.) Dizziness 4.) Unconsciousness 5.) Death if untreated
Why doesn’t copper follow the usual rules for electronic configuration?
Copper prefers to have a full 3d subshell and just one electron in the 4s subshell
What is the manganese ion with the oxidation state +7?
MnO₄⁻
Other than strength of absorption why not absorption of reactants onto the catalyst not always result in a reaction?
The reactants might not have been correctly orientated
What are the two steps for what is happening in the contact process?
1.) V₂O₅ oxidises the SO₂ to SO₃ and is reduced itself to V₂O₄ 2.) Then the V₂O₄ is oxidised back to V₂O₅ by oxygen
What is haemoglobin called when it has a carbon monoxide ligand?
Carboxyhaemoglobin
Why do you have to use an inert atmosphere when reducing Cr³⁺ to Cr²⁺?
Cr²⁺ ions are easily oxidised back into Cr²⁺ ions in air
Name three physical properties of transition metals.
1.) High density 2.) High melting and boiling point 3.) Similar ionic radii
Why do are complex ions coloured in three points?
1.) electrons require energy to jump between the ground state and the excited state within the 3 subshell 2.) this energy comes from visible light - it absorbs certain frequencies 3.) frequencies not absorbed are reflected and thats the colour you see
What is the equation for the reversible reaction that turn Cr₂O₇²⁻ into CrO₄²⁻ ions
Cr₂O₇²⁻ + H₂O ⇋ 2CrO₄²⁻ + 2H⁺
After the initial reaction between MnO₄⁻ and C₂O₄²⁻ what two reactions begin to happen?
1.) 4Mn²⁺ + MnO⁴⁻ + 8H⁺→ 5Mn³⁺ + 4H₂O 2.) 2Mn³⁺ + C₂O₄²⁻ → 2Mn²⁺ + 2CO₂
What are four side affects of cisplatin?
1.) Hair loss 2.) Suppressed immune system 3.) Increased risk of infection 4.) Damage to the kidneys
Why do transition metals make good catalyst?
They have variable oxidation states so they can transfer electrons to speed up reactions
What catalyst is used in the reaction between S₂O₈²⁻ and I⁻ions
Fe²⁺
Name two reactions that use homogeneous catalysts
1.) The reaction between peroxodisulphate (S₂O₈²⁻) ions and iodide (I⁻) ions 2.) The reaction between manganate (VII) ions (MnO₄⁻) and ethandioate ions (C₂O₄²⁻)
What are titrations using transition metals often called?
Redox titrations
Why is chromium more common with an oxidation state of +3 rather than +2?
+2 is a lot less stable
What is a heterogeneous catalyst?
One that is in a different phase from the reactants
Name a complex ion with a coordination number of 4 and the shape square planar.
Cisplatin
What are the two ways you can form Co³⁺ from Co²⁺ ions?
Co²⁺ ions are oxidised by hydrogen peroxide in acidic solution, or they are oxidised in air with ammonical solution
Why is the reaction between S₂O₈²⁻ and I⁻ ions?
Both ions are negatively charged and so repel each other
How do you form CrO₄²⁻ from Cr³⁺ ions?
Cr³⁺ are oxidised by hydrogen peroxide in alkaline solution
What are the two steps in the reaction between S₂O₈²⁻ and I⁻ ions when there is an Fe²⁺ catalyst?
1.) Fe²⁺ reduces the S₂O₈²⁻ to SO₄²⁻ and is oxidised to Fe³⁺ itself 2.) Fe³⁺ oxides the I⁻ to I₂ and is reduced to Fe²⁺ itself
What is a coordinate bond?
A covalent bond in which both electrons in the shared pair come from the same atom
Name two larger ligands.
Chloride ions
How is Tollen’s reagent prepared?
By adding just enough ammonia solution to silver nitrate solution
How do you find the oxidation state of a metal ion within a complex ion?
Total oxidation state of the complex ion - the sum of the oxidation states of the ligands
Is catalyst poisoning a problem for both heterogeneous and homogeneous catalysts? And why?
Only heterogeneous being the reaction during occur on the surface of homogeneous catalyst
What is the equation for the titration off Fe²⁺ against Cr₂O₇²⁻?
Cr₂O₇²⁻ + 14H⁺ + 6Fe²⁺→ 2Cr³⁺ + 7H₂O + 6Fe³⁺
What is a transition metal?
A metal that can form on for more stable ions with a partially filled d sub shell
What two oxidation states can cobalt exist as?
+2 and +3
Draw what cisplatin looks like.
What are two reasons why the rhodium catalyst is placed over a lattice structure in catalytic converters?
1.) Maximises surface area increasing the rate of reaction 2.) Minimises costs as only a thin layer is needed
What colour is the Cr₂O₇²⁻ ion?
Orange
What is the shape and bond angle for complex ions with the coordination number of 6?
Octahedral - 90
What do you start with when trying to form Co³⁺ from Co²⁺ ions?
[Co(H₂O)₆]²⁺
What are three rules for drawing electronic configuration?
1.) electrons fill up the lowest energy subshells first 2.) electrons fill singly before they start sharing a orbital 3.) 4s is usually filled up before 3d, because it has a lower energy level
Which two d block metals aren’t transition metals?
Zinc and scandium
Why is it bad if catalysts absorb the reactants too weakly (two reasons)?
1.) The reactants aren’t brought together for long enough 2.) There is no increase in concentration of reactants on the surface
What shape and bond angle do some metal complexes form with a coordination number of 4 very rarely form?
Square planar - 90
What colour is the Cu²⁺ ion?
Blue
What colour is [Co(H₂O)₆]²⁺?
Pink solution
What is a ligand?
An atom, ion or molecule that donates a pair of electrons to a central metal ion
Why is it bad when CO is inhaled?
Haemoglobin substitute its water ligands for carbon monoxide ligands, carbon monoxide is a strong ligand so can’t be easily exchanged meaning the haemoglobin can no longer transport oxygen
What transition metals do you have to know about?
Between Tin and Copper
What are the three steps in how heterogenous catalyst works?
The reactants are absorbed onto the surface, the reaction happens and then the products are reabsorbed
Draw what the ethanedioate ion looks like.
What is the colour change in this reaction: 2Cr³⁺ + Zn → Zn²⁺ + 2Cr²⁺ ?
Green to Blue
What is the colour of the V³⁺ ion?
Green
What do the graphs of enthalpy profile of a reaction catalysed by a homogeneous catalyst look like? And why?
Two humps for the two reaction that are happening
What colour is the MnO₄⁻ ion?
Purple
Describe what happens during spectrometry to find the concentration of a complex ion in a solution (in four steps)?
1.) Light is shone through a filter which only lets the colour of light through that is absorbed by the sample 2.) The light then passes to a colorimeter 3.) The colorimeter shows how much light was absorbed by the sample 4.) More light absorbed the more concentrated
What catalyst is used in catalytic converters
Rhodium
Draw what a hameoglobin looks like.
What is the colour change that happens in this reaction: Cr₂O₇²⁻ + H₂O → 2CrO₄²⁻ + 2H⁺ ?
Orange to yellow
What is the colour of the VO₂⁺ ion?
Yellow
How can you turn CrO₄²⁻ into Cr₂O₇²⁻ ions?
Putting it into acidic conditions - H⁺ ions
What catalyst is used in the contact process?
Vanadium (V) oxide - V₂O₅
What colour is the Fe²⁺ ion?
Pale green
Give two reasons why catalyst poisoning increase costs?
1.) Less product being made within a certain time 2.) Money has to be spent on replacing or regenerating
Name the name chromium ions with the oxidation state of +6?
Cr₂O₇²⁻ and CrO₄²⁻
What molecule can disrupt haemoglobin transporting oxygen around the body?
Carbon monoxide - CO
What is the overall equation for what is happening during the haber process?
N₂ + 3H₂ → 2NH₃
What is the purpose of catalytic converters?
Clean up emissions form cars
What is cisplatin used for?
Anticancer drug
What shape structure does haemoglobin have?
Octahedral
What molecule do the nitrogen atoms come from which are bonded to haemoglobin?
A multidentate ligand called porphyrin
Name four chemical properties of transition metals.
1.) They can form complex ions 2.) They form coloured ions 3.) They are catalytic active 4.) They have variable oxidation states
Why is it bad if catalysts absorb the reactants too strongly?
The products aren’t easily deabsorbed
Why don’t metals with a full or empty d subshells have colours?
The colour comes from them absorbing light and the electrons jumping between states, if the shell was full or empty then there would be no electrons to jump
What is the vanadium ion with the oxidation state +5?
VO₂⁺
What is a support medium?
Something a heterogeneous catalyst is out on to maximise surface area and minimise cost
What part of haemoglobin is called a haem?
The Fe²⁺ central ion and the four nitrogen atoms that form a circle around it
Why isn’t zinc a transition metal?
The only ion it forms, Zn²⁺ has a full d subshell
How many electrons and orbitals are there in s, p and d subshells
s - 2 electrons - 1 orbital p - 6 electrons - 3 orbitals d - 10 electrons - 5 orbitals
What are the two equations for what is happening in the contact process?
1.) V₂O₅ + SO₂ → V₂O₄ + SO₃ 2.) V₂O₄ + 1/2O₂ → V₂O₅
