transition metall

Question 1

the characteristics of a transition metal

Answer 1

*complex formation, *formation of coloured ions, *variable oxidation state
*catalytic activity.

Question 2

what is a ligand complex

Answer 2

d: an atom, ion or molecule which can donate a lone electron pair.
is a central metal ion surrounded by ligand

Question 3

what is a coordinate bond

Answer 3

Co-ordinate bonding is when the shared pair of electrons in the covalent bond
come from only one of the bonding atoms

Question 4

.examples of bidentate ligands

Answer 4

.g. NH2CH2CH2NH2 and ethanedioate ion C2O42-

Question 5

examples of monodentate ligands

Answer 5

H2O, NH3 and Cl− can act as monodentate liga

Question 6

describe ligand substitiution of cobalt complex

Answer 6

[Co(h20)6] 2 plus aq) + 6NH3 (aq)–> [Co(NH3)6]

Question 7

what is a bidentate ligand

Answer 7

Ligands can be bidentate (e.g. NH2CH2CH2NH2 and ethanedioate ion C2O4
2- ) which
have two atoms with lone pairs and can form two coordinate bonds per ligand

Answer 8

Oxygen forms a co-ordinate bond to Fe(II) in
haemoglobin, enabling oxygen to be
transported in the blood.
CO is toxic to humans because CO can form a
strong coordinate bond with haemoglobin. This is a
stronger bond than that made with oxygen and so it
replaces the oxygen, attaching to the haemoglobin.

Question 9

desribe the chelate effect in a reaction

Answer 9

when there is a ligand subsitution where its repalced with a multidentate ligand
In this reaction there is an increase in the entropy because there are more moles of products than
reactants (from 2 to 7), creating more disorder.

Question 10

what determines the colour change

Answer 10

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

Question 11

what causes colour in a transition metal

Answer 11

A portion of visible light is absorbed to promote d
electrons to higher energy levels. The light that is not
absorbed is transmitted to give the substance colour

Question 12

which element does not form compounds with colour

Answer 12

Scandium is a member of the d block. Its ion
(Sc3+) hasn’t got any d electrons left to move
around.

Question 13

what is the trend with transition metals with the oxidising and reducing ability

Answer 13

*Compounds with high oxidation states tend to be oxidising agents
e.g. MnO4
- *Compounds with low oxidation states are often reducing agents e.g.
V2+ & Fe2+

Question 14

what is tollens reagent

Answer 14

[Ag(NH3)2]+
is used in Tollens’

Question 15

what is a hetrogenous catalyst

Answer 15

A heterogeneous catalyst is in a different phase from the reactants

Question 16

what is a homogenous catalyst

Answer 16

A homogeneous catalyst is in the same phase as the reactants

Question 17

what are the steps of hetrogenous catalyst

Answer 17

Reactants form bonds with atoms at active sites on
the surface of the catalyst (adsorbed onto the
surface)
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 in turn weakens bonds between product and
catalyst and product leaves (desorbs)
5.powder pellet added to increases surface area
6.Catalysts can become poisoned by impurities
and consequently have reduced efficiency

Answer 18

Increasing the surface area of a solid catalyst will improve its effectiveness. A support medium is often
used to maximise the surface area and minimise the cost (. Rh on a ceramic support in catalytic
converters).

Question 19

what are the half equations for the contact process

Answer 19

step 1 SO2 +V2O5–> SO3 + V2O4
step 2 2V2O4 + O2–> 2V2O5

Answer 20

stage 1
S2O8 2- + 2Fe2+ –>2SO4 2- + 2Fe3+

stage2
2I- + 2Fe3+ 2Fe2+ +

Question 21

why is iron added into the reaction between iodine and persulfte ions

Answer 21

The uncatalysed reaction is very slow because the reaction
needs a collision between two negative ions. Repulsion
between the ions is going to hinder this – meaning high
activation

Question 22

what catalyses the reaction between persulfate and iodide

Answer 22

Fe 2+

Question 23

what is auto catalysis

Answer 23

autocatalysis where one of
the products of the reaction can catalyse the
reaction.

Answer 23

Step 1 4Mn2+ + MnO4
- + 8 H5Mn3+ + 4 H2O
Step 2 2Mn3+ + C2O4
2-  2Mn2+ + 2 CO2