Transition Metals

Question 1

Define transition metals

Answer 1

Elements that contain an incomplete d-subshell of electrons as either an atom or an ion

Question 2

Properties of transition metals

Answer 2

Form complexes
These complexes tend to be coloured
Variable oxidation states
Can act as catalysts

Question 3

Define ligand

Answer 3

Molecule/ion that forms a coordinate bond to a metal by donating a pair of electrons

Question 4

Define Lewis base

Answer 4

Electron pair donator

Question 5

Define Lewis acid

Answer 5

Electron pair acceptor

Question 6

Define complex

Answer 6

Metal atom surrounded by ligands

Question 7

Define coordination number

Answer 7

The number of coordinate bonds around a metal ion

Question 8

How many coordinate bonds does copper normally have

Answer 8

6

Question 9

What are the three types of ligand

Answer 9

Unidentate
Bidentate
Multidentate

Question 10

Define unidentate

Answer 10

Forms 1 coordinate bond per molecule

Question 11

Examples of unidentate ligands

Answer 11

NH3, H2O, Cl-, CN-

Question 12

Define bidentate

Answer 12

Forms 2 coordinate bonds per molecule

Question 13

Examples of bidentate ligands

Answer 13

1,2-diaminoethane, ethandioate ions

Question 14

Define multidentate ligands

Answer 14

Forms multiple coordinate bonds per molecule

Question 15

Examples of multidentate ligands

Answer 15

EDTA and polyphyrin

Question 16

Which shape had the most ligand complexes

Answer 16

Octahedral

Question 17

Which shape usually contains Cl- ligands

Answer 17

Tetrahedral

Question 18

What metal ions are usually in square planar shapes

Answer 18

Pt2+ and Ni2+

Question 19

What shape is cis-platin

Answer 19

Square planar

Question 20

What shape are complexes with a Ag+ metal ion

Answer 20

Linear

Question 21

Which type of ligands can have geometric isomerism

Answer 21

Unidentate ligands

Question 22

Which type of ligand can display optical isomerism

Answer 22

Bidentate ligands

Question 23

What changes the ease at which metals are oxidised

Answer 23

The pH of the solution and the nature of the ligands attached

Question 24

What do Alkaline conditions cause in a ligand complex

Answer 24

Hydrolysis of the ligand
This results in a complex with an increasingly negative charge
This causes easier oxidation as the ion is negative

Question 25

What does acidic conditions cause in a ligand complex

Answer 25

Prevents hydrolysis from taking place and the H+ ions provide electrons that reduce the complex ion

Question 26

Is Zn an oxidising or reducing agent

Answer 26

Reducing

Question 27

In a potassium manganite titration what properties must the acid have

Answer 27

Be strong, many H+ Not an oxidising agent (could react with the sample) Not be a reducing agent (could react with MnO4- ions)

Question 28

Why can't you use HCl in potassium manganate titrations

Answer 28

oxidised to Cl- by MnO4

Question 29

why can't you use HNO3 in potassium manganate titrations

Answer 29

it is an oxidising agent

Question 30

why can't you use concentrated H2SO4 in potassium manganate titrations

Answer 30

it could be an oxidising agent

Question 31

why does potassium manganate act as its own indicator

Answer 31

the pink colour intensifies due to an excess of Mn2+ once all of the Fe2+ have reacted

Question 32

what is the colour change for a potassium dichromate titration

Answer 32

orange to blue/green

Question 33

why is sodium diphenylaminesulphonate used in potassium dichromate titrations

Answer 33

to give a clearer end point, colourless to purple

Question 34

steps for redox titration calculations

Answer 34

write the half equations for the oxidising agent and reducing agent combine equations calculate the number of mols of the oxidising agent (MnO4 or CrO7) calculate the number of mols of reducing agents calculate the number of mols in the original solution determine the concentration of the original solution or percentage of reducing agent

Question 35

the two commonly used oxidising agents when completing a redox titration with Fe2+

Answer 35

potassium dichromate and potassium manganate

Question 36

the two equations which find number of mols

Answer 36

n=cv | mols=mass/Mr

Question 37

define heterogeneous catalyst

Answer 37

a catalyst in a different phase from the reactants

Question 38

define homogeneous catalyst

Answer 38

a catalyst in the same phase as the reactants

Question 39

what makes a good catalyst

Answer 39

good adsorption or reactant molecules and the good desorption of products

Question 40

how does adsorption of a reactant onto a metal surface speed up a reactant

Answer 40

weakening bonds within the reactant molecule, reducing the Eact causing a reactant molecule to break up onto more reactant molecules, lowering the Eact holding a reactant in a particular position, increasing the chance of a collision in a favourable position giving a higher concentration of a reactant on the catalyst surface increasing the chance of a favourable collision with another reactant

Question 41

how is a catalyst poisoned

Answer 41

the active sites are blocked

Question 42

how does homogeneous catalysis proceed

Answer 42

via a catalyst

Question 43

when does autocatalysis occur

Answer 43

when one of the products catalyses the reaction

Question 44

what is the acidity of solutions of metal ions decided by

Answer 44

charge of the metal ion | size of the metal ion

Question 45

why does charge of the metal ion affect pH

Answer 45

larger charge=greater dissociation=lower pH

Question 46

why does size of the metal ion affect pH

Answer 46

greater ionic charge to size ratio = greater dissociation = lower pH

Question 47

is the pH of a solution of M3+ ions or Mn2+ ions lower pH

Answer 47

Mn3+ ions