Inorganic chemistry - year 2

homogenous catalyst

same physical state as reactants

heterogenous catalyst

different physical state to reactants

Fe in haber process

heterogeneous

V2O5 in contact process

heterogeneous

MnO4- ions in oxidation of ethanedioic acid

homogeneous

Fe2+ ions in the iodineperoxodisulfate reaction

homogeneous

vanadium reaction

V2O5 + SO2 = V2O4 + SO2

• oxidises SO2 and reduced itself

V2O4 + 1/2O2 = V2O5

• reduced catalyst is oxidised by oxygen back to original state

catalyst poisioning and affect on catalytic activity

unwanted impurities bind onto catalysts surface( reduces surface area)

reduces cataylitic activity

may need to replace catalyst - expensive

autocatalysis

product formed from reaction acts as a catalyst in the same reaction

explain with use of half equations how manganese (II) ions autocatalyse the reaction between C4O4(2-) and MnO4-

MnO4- ions oxidise Mn2+ ions to Mn3+ ions

4Mn2+ + MnO4- + 8H+ = 5Mn3+ + 4H2O

Mn3+ ions oxidise C4O4 2- ions to produce CO2 and regenerate Mn2+ ions

2Mn3+ + C2O4(2-) = 2CO2 + 2Mn2+

explain with equations how Fe2+ ions catalyse S2O8(2-)

2Fe2+ + S2O8(2-) = 2Fe3+ + 2SO4(2-)

2Fe3+ + 2I- = 2Fe2+ + I2

oxidation of Fe2+ to Fe3+

reduction of Fe3+ to Fe2+ by I-

why do 3+ metal aqua ions form more acidic solution than 2+ metal aqua ions

• metal 3+ ions have a higher charge density

• Makes 3+ ions more polarising so they attract electrons from oxygen atoms of co-ordinated water molecules more strongly - WEAKENS OH Bond

• More likely for a H+ ion to be released

amphoteric

metal hydroxides act as a an acid or base (dissolve in an excess base or acid).

(Cu(H2O)6)2+ with OH- or NH3

Cu(OH)2(H2O)4 - blue ppt

(Cu(H2O)6)2+ - with excess OH-

no change

(Cu(H2O)6)2+ - with excess NH3

(Cu(NH3)4(H2O)2)2+ -deep blue solution

(Cu(H2O)6)2+ - with Na2CO3

CuCO3 green- blue ppt

(Fe(H2O)6)2+

green solution

(Fe(H2O)6)2+ - with OH- or NH3

Fe(OH)2(H2O)4 - green ppt

(goes brown in standing air)

(Fe(H2O)6)2+ - with excess OH-

no change

(Fe(H2O)6)2+ - with excess NH3

no change

(Fe(H2O)6)2+ - with Na2CO3

FeCO3 - green ppt

(Al(H2O)6)3+

colourless solution

(Al(H2O)6)3+ - with OH- or NH3

Al(OH)3(H2O)3 - white ppt

(Al(H2O)6)3+ - with excess OH-

(Al(OH)4)- - colourless solution

(Al(H2O)6)3+ -with excess NH3

no change

(Al(H2O)6)3+ - with Na2CO3

Al(OH)3(H2O)3

(Fe(H2O)6)3+

yellow solution

(Fe(H2O)6)3+ - with OH- or NH3

Fe(OH)3(H2O)3

(Fe(H2O)6)3+ - with excess OH-

no change

(Fe(H2O)6)3+ - with excess NH3

no change

(Fe(H2O)6)3+ - with Na2CO3

Fe(OH)3(H2O)3 - brown ppt