15.2.2 - Reactions of cobalt and iron complexes

Question 1

What is the observation when hexaaquacobalt(II) reacts with sodium hydroxide?

Answer 1

Pink solution forms a blue precipitate.

Question 2

What type of reaction is it when hexaaquacobalt(II) reacts with sodium hydroxide? (2 moles)
What is the formula of the precipitate?

Answer 2

Acid - base reaction
(Co(H2O)4(OH)2)

Question 3

When ammonia is added to hexaaquacobalt(II) the change is a pink solution to a blue precipitate.
What happens when excess ammonia is added to the precipitate?

Answer 3

The reaction is a ligand exchange reaction.
The precipitate dissolves to form a brown solution.

Question 4

Write the equation of the reaction between the hexaaquacobalt(II) ion and Cl- (HCl)

Answer 4

(CO(H2O)6)2+ + 4Cl- = (CoCl4)2- + 6H2O

Question 5

What is observation can be made in the reaction between hexaaquacobalt(II) and hydrochloric acid and what type of reaction is this?

Answer 5

Pink solution forms blue solution
Coordination number change

Question 6

What observation can be made when sodium hydroxide is added to the hexaaquairon(II) iron?
What type of reaction is this?

Answer 6

Pale green solution forms a green precipitate
Acid-base reaction.

Question 7

Upon standing, what happens to the (Fe(H20)4(OH)2) green precipitate?

Answer 7

Changes to brown and oxygen from the atmosphere causes oxidation.

Question 8

Write the equation for when sodium hydroxide is added to a solution containing the hexaaquairon(III) ion.

Answer 8

(Fe(H2O)6)3+ + 3OH- = (Fe(H20)3(OH)3) + 3H2O

Question 9

What is the observation when sodium hydroxide is added to a solution containing the hexaaquairon(III) ion.

Answer 9

a yellow-brown solution forms a brown precipitate.