Transition metals

Question 1

transition metals definition

Answer 1

incomplete d sub shell

Question 2

complex

Answer 2

central metal ion surrounded by ligands

Question 3

ligand

Answer 3

an atom, ion or molecule which can donate a lone electron pair

Question 4

co-ordinate number

Answer 4

the number of co-ordinate bonds formed to a central metal ion

Question 5

monodentate

Answer 5

one coordinate bond per ligand

Question 6

bidentate

Answer 6

two atoms with lone pairs and can form two coordinate bonds per ligand

Question 7

chemical properties of transition metals

Answer 7

form complexes, form coloured ions, variable oxidation states and good catalysts

Question 8

what’s ligand substitution

Answer 8

NH3 and H2O exchanged

Question 9

chelate effect

Answer 9

more molecules of products than reactants in terms of a positive entropy change

Question 10

octahedral complex bond angle

Answer 10

90

Question 11

when does optical isomerism happen in ligands?

Answer 11

bidentate ligands

Question 12

tetrahedral complex bond angle

Answer 12

109.5

Question 13

square planar complexes bond angle

Answer 13

90

Question 14

linear complexes bond angle

Answer 14

180

Question 15

VO2+ colour

Answer 15

yellow

Question 16

VO^2+ colour

Answer 16

blue

Question 17

V3+ colour

Answer 17

green

Question 18

V2+ colour

Answer 18

violet

Question 19

balanced ionic equation with MnO4-

Answer 19

MnO4- + 8H+ + 5e- > Mn2+ + 4H2O

Question 20

equation with Fe2+

Answer 20

Fe2+ > Fe3+ + e-

Question 21

equation with C2O4 2-

Answer 21

C2O4 2- > 2CO2 + 2e-

Question 22

reacting molar ratio between MnO4- : C2O42-

Answer 22

2:5

Question 23

reacting molar ratio between between MnO4- : Fe2+

Answer 23

1:5

Question 24

reacting molar ratio between C2O4 2- : Fe2+

Answer 24

1:2

Question 25

heterogeneous catalysts

Answer 25

different phase or state of catalysts and reactants

Question 26

homogeneous catalysts

Answer 26

same phase or state of catalysts and reactants

Question 27

autocatalysis

Answer 27

one of the products act as catalyst

Question 28

what are the ways colour change arises?

Answer 28

1. oxidation state
2. co-ordination number
3. ligand

Question 29

how do colour complexes arise?

Answer 29

electronic transitions from the ground state to excited states between different d orbitals.

a portion of visible is absorbed, the colour that isn’t determines the ions colour

Question 30

energy with wavelength equation

Answer 30

E= hv or E=hc/wavelength

Question 31

what happens when changing a ligand or coordination number?

Answer 31

alter the energy split between the d-orbitals, hence changing the frequency of light absorbed.

Question 32

method of spectrophotometry

Answer 32

1. add an appropriate ligand to intensify colour
2. make up solutions of known concentration
3. measure absorption
4. plot a graph of absorption vs concentration
5. measure absorption of unknown and compare

Question 33

what may lead to catalytic action?

Answer 33

absorption of reactants at active sites on the surface - reactants adsorb

Question 34

steps in heterogeneous catalysis

Answer 34

1. reactants form bonds with atoms at active sites on the surface of the catalyst
2. as a result bonds in the reactants are weakened and break
3. new bonds form between the reactants held close together on catalyst surface
4. This is turn weakens bonds between product and catalyst - products leaves

Question 35

eg of hetreogeneous catalysts

Answer 35

V2O5 - contact process
C2O3

Question 36

contact process steps

Answer 36

SO2 + V2O5 > SO3 + V2O4
2V2O4 + O2 > 2V2O5

overall equation: 2SO2 + O2 > 2SO3

Question 37

eg of homogeneous catalysts

Answer 37

S2O82- + 2I- > 2SO42- + I2

Question 38

tollen’s reagant

Answer 38

Ag(NH3)2