Reactions of aqueous ions

Question 1

Why are metal 3+ ions more acidic than 2+ ions?

Answer 1

• 3+ metals are small but w/ big charge - higher charge density than 2+
• Makes it much more polarising - attract e- from oxygen atom of co-ordinate bond, weakening O-H
• More likely H+ released

Question 2

What happens when you add OH- ions to metal aqua ions?

Answer 2

Produces insoluble metal hydroxides

Question 3

How many steps is needed to make an insoluble uncharged metal hydroxide in metal aqua 3+ ions?

Answer 3

3

Question 4

How many steps is needed to make an insoluble uncharged metal hydroxide in metal aqua 2+ ions?

Answer 4

2

Question 5

The metals in metal aqua 2+ ions are limited to..

Answer 5

• Fe
• Cu

Question 6

The metals in metal aqua 3+ ions are limited to..

Answer 6

• Al
• Fe

Question 7

Which metal hydroxide ppt is amphoteric?

Outline how it works

Answer 7

• Aluminium hydroxide
• Presence of base: acts as bronsted lowry acid, donates H+ to OH-
• Presence of acid: acts as bronsted lowry base, accepts H+ from H3O+

Question 8

What happens when you react metal aqua 2+ ions w/ sodium carbonate?

Answer 8

Produces insoluble metal carbonate

Question 9

Reactions w/ sodium hydroxide

Answer 9

• All produce ppt
• Excess: aluminium hydroxide will dissolve bc amphoteric

Question 10

Reactions w/ ammonia

Answer 10

• All produce ppt
• Excess: copper hydroxide dissolves bc undergoes ligand sub - deep blue sol

Question 11

Reactions w/ sodium carbonate

Answer 11

• All form ppt
• Al3+ + Fe3+ give off bubble

Question 12

Which is the only metal aqua ion that changes when reacted w/ excess OH-?

Answer 12

[Al(H2O)6]3+

Question 13

Which is the only metal aqua ion that changes when reacted w/ excess NH3?

Answer 13

[Cu(H2O)6]2+

Question 14

What are the steps to testing unknown substances?

Answer 14

• Add sodium hydroxide sol drop wise, add in excess
• Add ammonia sol dropwise, add in excess
• Add sodium carbonate sol