TRANSITION METALS Flashcards
define what transition metal is
D block elements forming one or more stable ions with incomplete D orbitals
what properties do transition metals have
- variable oxidation states (apart from Sc 3+ and Zn 2+)
- form coloured compounds
- used as catalysts
when is iron used as a catalyst
HABER PROCESS
- making ammonia
- N2 (g) + 3H2 (g) –> 3NH2 (aq)
THIOSULFATE + IODIDE (Fe 3+)
- S2O8(2-) + Fe(2+) –> 2SO4(2-) + Fe(3+)
2Fe(3+) + 2I- –> I2 + 2Fe(2+)
when is nickel used as a catalyst
HYDROGENATION
- margarine manufacture
- CH2CH2 + H2 –> CH3CH3
Ni / 150ºc
when is Cu(2+) used as a catalyst
ZINC + SULFURIC ACID TO MAKE H2
- Zn + H2SO4 –> ZnSO4 + H2
Cu(2+)
when is vanadium oxide used as a catalyst
CONTACT PROCESS ( step 2) - making sulfuric acid
1. S (l) + O2 (g) --> SO2 (g) \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ *2. 2SO2 (g) + O2 (g) 2SO3 (g) V2O5 \_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_\_ 3. SO3 (g) + H2SO4 (l) --> H2S2O7 (l) H2S2O7 (l) + H20 (l) --> 2H2SO4 (l)
why are trans. mets. good catalysts
partially filled d orbitals can be used to form bonds w/ ADsorbed reactant which helps reactions take place more easily
define complex ion
a central metal ion co-ordinately bonded to one or more molecule / negative ion
define ligand
a molecule/ion that donates a pair of e- to a central metal ion to form a co-ordinate bond
define co-ordination number
the total number of co-ordinate bonds formed between the central metal ion + any ligands
colour of Cu(2+) solution
pale blue
copper + NaOH (aq)
observation and ionic equation
forms pale blue ppt - Cu(OH)2
Cu(2+) (aq) + 2OH(-) (aq) –> Cu(OH)2 (s)
copper + XS NaOH (aq)
pale blue ppt - CU(OH)2, does NOT dissolve
copper (+NH3) + XS NH3
forms a blue ppt at first - [Cu(OH)2(H2O)4]
but dissolves w/ XS to make a royal blue solution - Cu(NH3)4(H2O)2
NH3 ACTS AS A BASE [Cu(H2O)6](2+) (aq) + 2NH3 (aq) --> [Cu(OH)2(H2O)4] (s) + 2NH4(+)
XS NH3
[Cu(OH)2(H2O)4] (s) + 4NH3 –> Cu(NH3)4(H2O)2 (aq) + 2H2O (l) + 2OH(-) (aq)
copper + HCL
observation and ionic equation
colour of iron (II) solution
pale green - Fe(2+)
iron (II) + NaOH
observation and ionic equation
forms green ppt - Fe(OH)2
Fe(2+) (aq) + 2OH(-) (aq) –> Fe(OH)2 (s)
OXIDISES TO BROWN IN AIR - Fe(OH)3
iron (II) + XS NaOH
green ppt - Fe(OH)2, does NOT dissolve
colour iron (III) solution
pale yellow - Fe(3+)
iron (III) + NaOH
observation and ionic equation
rusty brown ppt - Fe(OH)3
Fe(3+) (aq) + 3OH(-) (aq) –> Fe(OH)3 (s)
iron (III) +XS NaOH
rusty brown ppt - Fe(OH)3, does NOT dissolve
colour of manganese solution
pale pink - Mn(2+)
manganese + NaOH
observation and ionic equation
light brown ppt - Mn(OH)2
Mn(2+) (aq) + 2OH(-) (aq) –> Mn(OH)2 (s)
darkens in air
manganese + XS NaOH
light brown ppt - Mn(OH)2, does NOT dissolve
colour of chromium solution
pale purple - Cr(3+)
unless SO4(2-) (green)
chromium + NaOH
observation and ionic equation
grey green ppt - Cr(OH)3
Cr(3+) (aq) + 3OH- (aq) –> Cr(OH)3 (s)
chromium + XS NaOH
observation and ionic equation
chromium + XS NH3
purple solution - Cr(NH3)6
first forms grey green ppt - [Cr(OH)3(H2O)3]
dissolves on XS
what angle do ligands need to be for CIS isomerism
90º
diff. planes
what angle do ligands need to be for TRANS isomerism
180º
same planes
define ligand substitution
when one ligand is replaced by another
define optical isomers
non-superimposable mirror images
define strereo isomerism
same structural formula but atoms occupy different positions in space
how many bonds does a monodentate ligand form + examples
1 co-ordinate bond
H2O, Cl-, NH3
how many bonds does a bidentate ligand form + examples
2 co-ordinate bonds
NH2CH2CH2NH2 (en)
how many bonds does a multidentate ligand form + examples
several co-ordinate bonds
EDTA uses
- detergents
- reduce hardness in water
- food stabliser
- medicine > prevent blood clotting
how many lone pairs can EDTA donate
6
what is the charge of EDTA
4-
how many co-ordinate bonds can EDTA form
6 per molecule
name the transition metal complex used in the treatment of cancer
cis-platin
how may co-ordinate bonds can octahedral molecule have + bond angles
6
90º
how may co-ordinate bonds can planar molecule have + bond angles
4
90º
how may co-ordinate bonds can tetrahedral molecule have + bond angles
4
109.5º
how does cis-platin work
binds to DNA in fast growing cells
in presence of cis-platin fast growing cancer cells have incorrectly copied DNA + so it prevents replication
describe the bonding within a complex ion
ligand donates an e- pair
dative / co-ordinate bond is formed
why is iron (III) more acidic than iron (II)
- lone pair of e- on oxygen of H2O froms coordinate bond w/ iron ion
- bc iron is pos charge it pulls e- density towards it
- greater the charge, more pull on the e- in H2O molecule
- therefore easier to lose H ion
- therefore incr. in acidity
why can ethane - 1,2 - diamine (en) be classified as bidentate and what is its structural formula
- donates 2 lone pairs
- one from each N atom
- H2CH2CH2NH2
why is the ligands exchange reaction not a redox reaction
no change in oxidation state as e- not gained or lost
*link to Q if given specific molecule
when hexa-aqua copper reacts with Cl- why does the shape change from octahedral to tetrahedral
Cl- ligands are larger than H2O + are more neg charge. this makes tetrahedral more stable shape for the complex as there is less repulsion between ligands
when hexa-aqua copper reacts with Cl- why does the coodination number go from 6 to 4
Cl- ligands are larger than H2O + are more neg charge. thus instead forms 4 co-ordinate bonds, this makes tetrahedral shape which is more stable shape for the complex as there is less repulsion between ligands
write the ionic equation for hexa-aqua copper and HCL
what is ethane dioate
C2O4(2-)
BIDENTATE ligand