24.4 Ligand Substitution & Precipitation

Question 1

What is a ligand substitution reaction?

Answer 1

reaction in which 1 ligand in a complex ion

is replaced by another ligand

Question 2

Write an equation for the reaction between aqueous copper(II) ions + excess ammonia. What is the colour change?

Answer 2

[Cu(H₂O)₆]²⁺_(aq) + 4NH_{3 (aq)} ⟶ [Cu(NH₃)₄(H₂O)₂]²⁺_(aq) + 4H₂O_(l)

pale blue ⟶ dark blue

Question 3

Write an equation for the reaction between aqueous copper(II) ions + chloride ions. What is the colour change?

Answer 3

[Cu(H₂O)₆]²⁺_(aq) + 4Cl^-_(aq) ⇌ [CuCl₄]^2-_(aq) + 6H₂O_(l)

pale blue ⟶ yellow

Question 4

Write an equation for the reaction between aqueous chromium(III) + ammonia. What is the colour change?

Answer 4

[Cr(H₂O)₆]³⁺_(aq) + 6NH_{3 (aq)} ⟶ [Cr(NH₃)₆]³⁺ + 6H₂O_(l)

violet ⟶ purple

Question 5

What is the colour change when copper(II) ions react with excess ammonia?

Answer 5

pale blue ⟶ dark blue

Question 6

What is the colour change when copper(II) ions react with chloride ions?

Answer 6

pale blue ⟶ yellow

Question 7

What is the colour change when chromium(III) ions react with ammonia?

Answer 7

violet ⟶ dark green ⟶ purple

Question 8

Write a chemical equation for the precipitation reaction between copper(II) + sodium hydroxide the colour change:

Answer 8

Cu²⁺_(aq) + 2OH^-_(aq) ⟶ Cu(OH)_{2 (s)}

Pale blue ⟶ blue

Question 9

Write a chemical equation for the precipitation reaction between iron(II) + sodium hydroxide & the colour change:

Answer 9

Fe²⁺_(aq) + 2OH^-_(aq) ⟶ Fe(OH)_{2 (s)}

pale green ⟶ dark green

Question 10

Write a chemical equation for the precipitation reaction between manganese(II) + sodium hydroxide & the colour change:

Answer 10

Mn²⁺_(aq) + 2OH^-_(aq) ⟶ Mn(OH)_{2 (s)}

Pale pink ⟶ Pale Brown

Question 11

Write chemical equations for the precipitation reaction between chromium(III) + sodium hydroxide:

(one equation for excess NaOH, one equation with equal NaOH)

Answer 11

Cr³⁺_(aq) + 3OH^-_(aq) ⟶ Cr(OH)_{3 (s)}

Cr(OH)_{3 (s)} + 3OH^-_(aq) ⟶ [Cr(OH)₆]^3-_(aq)