Transition Metals - Hydrolysis

Question 1

[M(H2O)6]+2 + H2O…

Answer 1

[M(H2O)5(OH)]+ + H3O+

Question 2

[M(H2O)]+3 + H2O…

Answer 2

[M(H2O)5(OH)]+2 + H3O+

More acidic solution with 3+ hexaaquaions

Question 3

Why are +3 more acidic than +2?

Answer 3

Smaller
Higher charge density
More polarising
Attracting the electron of the O on H2O ligand more strongly
Weakens O-H bond
O-H bond more easily broken 
H+ therefore more likely to be released 
Solution more acidic

Question 4

What happens to hexaaquaion solutions when a base is added?

Answer 4

Generally, remains on LHS of equation
Base added which neutralises H3O+
Decreases [H3O+]
Equilibrium shifts to RHS to increase [H3O+]
Causes hydrolysis to occur

Question 5

Sodium carbonate with 2+ ions?

Answer 5

Precipitation reaction

[M(H2O)6]+2 + CO3^-2 ➡️ MCO3 (s) + 6H2O

Question 6

Sodium carbonate with 3+ ions?

Answer 6

Hydrolysis reaction

[M(H2O)6]+3 + 3CO3^-2 ➡️ [M(H2O)3(OH)3] (s) + 3CO2 (g) + 3H2O

Question 7

Give the equation of carbonate ion reacting with acid, why does this happen? Why does this NOT happen with 2+ ions?

Answer 7

CO3^-2 + 2H3O+ ➡️ CO2 + 2H2O

Pushes equilibrium to RHS produces [M(H2O)3(OH)3] and CO2 effervescence.

Not acidic enough to push equilibrium to RHS, only metal carbonate formed instead (MCO3)

Question 8

What does AMPHOTERIC mean and which metal hydroxide is amphoteric?

Answer 8

Can react with an acid or a base.

Al(OH)3

Question 9

How does the amphoteric metal hydroxide act as a base?

Answer 9

Encourages hydrolysis reaction by reacting with H3O+

Question 10

How does the amphoteric metal hydroxide act as an acid?

Answer 10

Reverses hydrolysis as it increase the concentration of acid so equilibrium shifts to decrease concentration of acid hence favours LHS