Transition Metals Flashcards

Question

what shape can exhibit optical isomerism

Answer 1

octahedral when there are 3 bidentate ligands.

Answer 2

when molecules are mirror images of the other and therefore non-superimposable due to a chiral centre. the TM ion acts as the chiral centre, when would usually be a C

Answer 3

- coord number / the central TM (Ag, Pt) - will inform shape. so structure determined - is octahedral/square planar? - if yes could exhibit isomerism, now look at the ligands - if there are two of 1 and the rest are different, then geometric - if octahedral and there are 3 bidentate ligands bonded, then optical

Answer 4

when ligand/s in a TM ion complex is replaced by another it can be incomplete. it can cause a change in co-ordination number if the ligands are of different sizes/charges

Answer 5

introduce excess of the ligand you want to substitute in

Answer 6

bidentate and multidentate ligands replace monodentate ligands from complexes. they are better at forming TM ion complexes, to say that they form more stable complexes

Answer 7

measure of disorder. matter tends toward higher entropy because there is then a higher energy dispersal. spontaneous reactions increase entropy

Answer 8

heat content of a system, measure of the total energy of a system in kj per mole

Answer 9

enthalpy change could be negligible because number c. bonds is unchanged. however entropy increases because there are more particles in the products than reactants. so more thermodynamically favourable bc creates more disorder

Answer 10

- products have x particles and reactants have y (will be less than x) particles - so disorder increases - so increase in entropy, delta s is positive - so thermodynamically favourable. gibbs free energy change is negative

Answer 11

EDTA 4- good for binding harmful metals into nonharmful complexes

Answer 12

changes in 1. ox state (variable ox state therefore can change) 2. coord number (could be changed by ligand, would change shape) 3. ligand (known as a subsitution reaction) 4. tm itself

Answer 13

TM ions absorb some wavelengths of visible light and transmits others (in solution) / reflects others (in solids) colour depends on the absorption and transmission. colour is colour transmitted colour is determined by the gap in energy between low and high energy d orbitals which are split (in terms of energy value) by ligand bonding. this is d splitting due to ligand bonding. freq of light absorbed is this energy gap

Answer 14

t metals have partially filled d orbitals orbitals have specific energy values when ligands bond to the TM the orbitals become different energy values. the bonding splits them into different energy values when visible light strikes the complex, the e- absorb wavelengths and are excited to higher energy d orbitals the light transmitted is what we see

Answer 15

alters the energy split between d orbitals. the difference in energy is the energy needed/absorbed by the e- to become in an excited state. the energy required is supplied by the UV/visible light wavelengths. the energy gap determines colour

Answer 16

e = energy absorbed h = plancks constant 6.63x10^-34 v = freq of light absorbed Hz c = speed of light 3x10^8 ms^-1

Answer 17

measure of how much visible light is absorbed by a chemical substance and at what intensity light is transmitted

Answer 18

**UV-Vis spectroscopy** if you shine vis light through a sample and allows the spectrometer to detect which wavelengths of light are absorbed, the data will tell us which metal ion is present, its ox state and the type of ligands and their arrangement by measuring the absorbance/transmittance frequencies of a substance, you can identify it spectrometer in UV-Vis also uses whats called the Beer-Lambert law to relate the absorbance of light to the concentration of the absorbing species in the sample. the more conced your solution, the more it absorbs. this is the beer-lambert law. thus you can determine [] of a substance

Answer 19

conc of coloured ions in solution

Answer 20

by measuring absorbance. absorbance is related to conc because if more conced then will absorb more light (colour is fixed wavelengths observable only in the visible light spectrum.) so the colourimeter absorbance reading will be higher

Answer 21

create a series of known concs and measure their absorbance. this allows you to create a calibration curve ([] on x, absorbance on y) the line created can be read off to find what the [] is of an unknown substance once you have its absorbance reading

Answer 22

variable ox states colour is determined by this (one of the factors)

Answer 23

Green purple - may look yellow-brown due to aqua ion releasing 1h+

Answer 24

purple colourless

Answer 25

brick red ppt is copper 1 oxide blue solution

Answer 26

+5 VO2 with a +1 charge +4 VO with a 2+ charge [[above are vanadate ions]] +3 V3+ - its most stable form +2 V2+

Answer 27

you better get vanadium VO2 + yellow VO2+ blue V3+ green V2+ violet

Answer 28

reduction of vanadate (V) ions with zinc in acidic solution, with HCl test tube with cotton wool in it. Zn + HCl --> H2 + ZnCl the H2 is the reducing agent, it gets oxidised to water. Is h2 or zn the reducing agent?

Answer 29

VO2 + + 2H+ + e- ---> VO2+ + H2O yellow -> green because mixing primary colours as VO2+ gets formed -> blue

Answer 30

VO2+ + 2H+ + e- ---> V3+ + H2O blue -> green

Answer 31

V3+ + e- ---> V2+ green -> violet

Answer 32

oxidising, so going from lower to higher ox state 1. take out cotton wool 2. O2 in air acts as oxidising agent 3. alkaline conditions

Answer 33

a colour change, allowed by the variable ox state of Cu, allows for identification of aldehydes fehlings is blue solution containing Cu2+. when reduced to Cu(I) it forms brick red ppt CuO with O2 in air i presume red ppt formed = aldehyde present

Answer 34

K2Cr2O7 potassium dichromate primary and secondary alcohols are oxidised to aldehydes and ketones respectively Cr2O7 2- ions are reduced to Cr3+, the way chromium exists ORANGE TO GREEN Cr2O7 2- + 6e- + 14H+ --> 2Cr3+ + 7H2O

Answer 35

- Redox titration is used in chemistry to determine and quantify substances based on their oxidation-reduction reactions. - relies on the transfer of electrons between reactants, where one compound loses electrons and one gains electrons. - concentration of the unknown can be calculated by measuring amount of reagent needed for reaction to go to completion

Answer 36

5Fe2+ + MnO4– + 8 H+ → 5Fe3+ + Mn2+ + 4 H2O red: MnO4- + 8H+ + 5e- ---> Mn2+ + 4H2O ox: 5Fe2+ ---> 5Fe3+ + 5e- - need to use dilute sulfuric acid - manganate ion is purple, so if in burette is hard to see bottom of meniscus. when in burette colour change is colourless to purple. bc as soon as purple then thats when the reaction has just gone to completion and now MnO4- is in excess

Answer 37

red: 5e- + MnO4– + 8 H+ → Mn2+ + 4 H2O ox: C2O4^2- → 2CO2 + 2e- overall: 5C2O4^2- + 2MnO4– + 16H+ → 10CO2 + 2Mn2+ + 8H2O - the reaction is slow because it is between two negative ions, so the conical flask must be heated to 60C to increase

Answer 38

substance that speeds up the ROR without undergoing a permanent chemical change. they are involved in the reaction but get regenerted they are unchanged in chemical composition and amount it provides an alternative reaction route with a lower Ea they increase the no successful collisions bc more particles have Ea bc it is reduced.

Answer 39

variable ox state, so can act as oxidising and reducing agents (get reduced and oxidised), which is the basis for their catalytic activity they can easily change their ox states whereas other metals have 1 fixed ox state they can't easily revert back and forth from

Answer 40

catalyst in different phase to reactants solid catalyst catalysing gaseous/in solution reaction

Answer 41

has active sites, locations on surface of catalyst where adsorption can occur - adsorption is a chemical process, due to chemical bonding. - when the reactants adsorb and desorb(??) onto the surface, the local conc reactants on the surface of the catalyst is increased so freq successful collisions is increased. - it also puts strain on the bonds and weakens them so break more easily - puts molecules in optimal orientation

Answer 42

STRONG ENOUGH TO adsorb reactants and hold them in optimal orientation so can weaken bonds, lowering Ea, and increase local conc so increased success of collisions WEAK ENOUGH TO desorb products, allow reactants to desorb and adsorb so move along surface so active sites not occupied and unavailable/blocked

Answer 43

a foundation that catalyst is spread around eg honeycomb for catalyst in catalytic converters increased surface area will improve effectiveness/activity of catalyst because more active sites exposed

Answer 44

V2O5 in the contact process Fe in the haber process

Answer 45

catalyst V2O5 (vanadium oxide) to convert sulfur dioxide to sulfur trioxide Overall equation : 2SO2 + O2 → 2SO3 step 1 2SO2 + 2V2O5 → SO3 + V2O4 step 2 2V2O4 + O2 → 2V2O5

Answer 46

Fe is used as a catalyst in the Haber process N2 + 3H2 <=> 2NH3 sulfur impurities in natural gas, where the hydrogen comes from, binds and occupies active sites. sulfur is in natural gas naturally or put in deliberately so gas leaks smell

Answer 47

when impurities/contaminants bind to active sites of catalyst surface more strongly than reactants so they occupy and block active sites catalysts have reduced efficiency because less sites available, so ror deceases and yield decreases. also difficult to remove from catalyst, and removal damages catalyst, so must replace

Answer 48

the plat/pallad/rhodium catalyst can be poisond by lead. when occurs must replace converter because otherwise more pollutants escape into atmosphere recall that 2CO + 2NO → 2CO2 + N2 and unburnt HCs and N2 → CO2 + N2 + H2O

Answer 49

in the same phase as reactants, eg all aq

Answer 50

the reaction proceeds through an intermediate species. TM ion will have different ox state in intermediate than orginally, then will revert back. this is enabled by TM ions having variable ox states due to partially filled d orbitals, which can easily gain or lose e-

Answer 51

1. iodide and persulfate ions to form sulfate ions and iodine 2. autocatalysis reaction between ethanedioate and manganate ions

Answer 52

when the products of the reaction then catalyses the reaction

Answer 53

OVERALL S2O8^2- + 2I- → 2SO4^2- + I2 two opply charged ions so very high Ea CATALYSIS ROUTE stage 1 S2O8^2- + 2Fe2+ ---> 2SO4^2- + 2Fe3+ stage2 2I- + 2Fe3+ ---> 2Fe2+ + I2 steps can occur in either order so Fe3+ can also act as a catalyst

Answer 54

overall 2 MnO4- + 5 C2O4^2- + 16 H+ ---> 2Mn2+ + 10 CO2 + 8 H2O - slow because repulsion and big number of particles need to collide - speeds up when products start to get formed because the Mn2+ acts as catalyst for reaction. Step 1 4Mn2+ + MnO4- + 8 H+---> 5Mn3+ + 4 H2O Step 2 2Mn3+ + C2O4^2- ---> 2Mn2+ + 2 CO2 Mn2+ reacts with manganate ion reactant to form Mn3+ intermediate. then Mn3+ intermediate reacts with ethanedioate ion reactant to form Mn2+ again and CO2

Answer 55

slow to begin with because uncatalysed as products have ben formed, ror increases to rate of decreasing [reactant] increases, rapidly decreasing rate slows again because less reactants; getting used up plateaus because reactant/s depleted

Answer 56

is purple so more purple, more absorbance, more conced 1. take samples at intervals during exp 2. absorbance value is related to [MnO4-] 3. see how absorbance value changes over time 4. can have absorbance on graph over time

Answer 57

1. take samples at intervals during exp 2. titrate them. when reacted with reducing agent, end point being colourless, the moles of that reducing agent can be found (n=cv ; c known and v= titre) 3. determine molar ratio reacting in, redox eq maybes 4. so find moles MnO4- therefore in sample 5. sample has certain vol so c=n/v

Transition Metals Flashcards

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