15.2 1 Different types of reaction

Question 1

redox

Answer 1

the oxidation number of the transition metal changes

Question 2

acid-base reaction

Answer 2

one or more ligands gain or loose a hydrogen ion

Question 3

ligand exchange

Answer 3

one or more of the ligands round the transition metal ion is replaced by a different ligand

Question 4

coordination number change

Answer 4

the number of ligands change

Question 5

Fe2+ ions in solution

Answer 5

pale green-when exposed to air gradually turns yellow or brown
iron goes from +2 to +3
[Fe(H2O)6]2+ to [Fe(H2O)6]3+

Question 6

colour change of Fe2+ to Fe3+

Answer 6

best illustated using solid samples containing these ions

Question 7

aqueous sodium hydroxide is added to copper (ii) sulfate solution

Answer 7

Pale blue solution forms a blue precipitate
[Cu(H2O)6]2+ + 2OH-=[Cu(H2O)4(OH)2]+2H2O
Acid base reaction
two hydroxide ions have removed hydrogen ions from two of the water ligands
amphoteric behaviour =when acid added to blue preciptate convert back

Question 8

Amphoteric behaviour

Answer 8

ability of a species to react with both acids and bases

Question 9

when do you also get acid-base reaction with [Cu(H2O)6]2+

Answer 9

addition of aqueous ammonia
[Cu(H2O)6]2+ +2NH3 = [Cu(H20)4(OH)2]+2NH4+
to reverse add aqueous ammonia to blue preciptate will form a deep blue solution (original is a pale blue solution)
[Cu(H2O)4(OH)2]+4NH3=[Cu(NH3)4(H2O)2]2+ +2H2O+2OH-
Reverse is a ligand exchange reaction

Question 10

copper(II) sulfate solution and concentrated hydrochloric acid

Answer 10

acid added slowly and continuously
colour changes from blue to green to yellow
[Cu(H2O)6]2+ +4Cl- =(reversible) [CuCl4]2- 6H2O
six water ligands substituted by four chloride ions
coordination number goes from 6 to four
change in the coordination number
hexaaquacopper(II) ion is blue tetrachlorocuprate(II) ion is yellow green colour is the mixture

Question 11

cuprate

Answer 11

anionic copper complexes