Ions In Aqueous Solution

Question 1

Reactions of M2+ and M3+ with NaOH in a neutralisation reaction?

Answer 1

React as acids

[M(H2O)6]2+ + 2OH- -> M(H2O)4(OH)2 + 2H2O

[M(H2O)6]3+ + 3OH- -> M(H2O)3(OH)3 + 3H2O

Question 2

M2+ and M3+

Answer 2

2+ Fe2+ and Cu2+

3+ Fe3+ and Al3+

Question 3

colour of M2+ ppts when reacting with NaOH

Answer 3

green ppt Fe2+
blue ppt Cu2+

Question 4

colour of M3+ ppts after reacting with NaOH

Answer 4

brown ppt Fe3+
white ppt Al3+

Question 5

Aluminium ppt property

Answer 5

amphoteric
acts as an acid or base

Question 6

Adding XS H+ to aluminium ppt

Answer 6

[Al(H2O)6]3+

Question 7

Adding XS OH- to aluminium ppt

Answer 7

[Al(H2O)2(OH)4]-

Question 8

Reactions of M2+ and M3+ with NH3

Answer 8

[M(H2O)6]2+ + 2NH3 -> [M(H2O)4(OH)2] + 2NH4+

[M(H2O)6]3+ + 3NH3 -> M(H2O)3(OH)3 + 3NH4+

Question 9

Why are M3+ ions more acidic than M2+ ions

Answer 9

They have a greater attractive power and weakens the OH bond in a water ligand, releasing H+

Question 10

XS ammonia and Cu2+ ppt (+ colour)

Answer 10

[Cu(H2O)6(OH)2] + 4NH3 -> [Cu(H2O)2(NH3)4]2+ + 2H2O + 2OH-

dark blue

Question 11

M2+ reacting with Na2CO3 and product colour

Answer 11

[M(H2O)6]2+ + CO32- -> MCO3 + 6H2O

green for Fe2+
blue for Cu2+

Question 12

M3+ reacting with Na2CO3

Answer 12

2[M(H2O)6]3+ + 3CO32- -> 2[M(H2O)3(OH)3] + 3H2O + 3CO2

Question 13

M2+ reaction with 4Cl-

Answer 13

[M(H2O)6]2+ + 4Cl- -> [MCl4]2- + 6H2O

Question 14

M3+ reaction with 4Cl-

Answer 14

[M(H2O)6]3+ + 4Cl- -> [MCl4]- + 6H2O

Question 15

When do metal aqua ions form tetrahedral ions with 4 Cl- ions?

Answer 15

when reacting with conc HCl

Question 16

[CuCl4]2- colour

Answer 16

green

Question 17

[FeCl4]2- colour

Answer 17

yellow

Question 18

[AlCl4]- colour

Answer 18

white