Question

2. Please provide the balanced net ionic equations for the following reaction.
A) KI and (NH4)2S2O8 in aqueous solution
B) Na2S2O3 and I2 in aqueous solution

Answer 1

A)

Molecular equation

(NH₄)₂S₂O₈ (aq)  + 2 KI (aq) (NH₄)₂SO₄ (aq)  + I₂ (aq) + K₂SO₄ (aq)

_{​​​​​​}Ionic equation

2NH₄⁺ + S₂O₈^2- + 2 K⁺ + 2I^- 2 NH₄⁺ + SO₄^2- + I₂ + 2 K⁺ + SO₄^2-

Net ionic equation :

S₂O₈^2- (aq)  + 2 I^- (aq)   I₂ (aq)  + 2SO₄^2- (aq).

B)

Molecular equation :

2 Na₂S₂O₃ (aq)  + I₂ (aq) 2 NaI (aq) + Na₂S₄O₆ (aq)

Ionic equation :

4 Na⁺ + 2 S₂O₃^2- + I₂ 2 Na⁺ + 2 I^- + 2 Na⁺ + S₄O₆^2-.

Net ionic equation :

2 S₂O₃^2- (aq) + I₂ (aq)   2 I^- (aq) + S₄O₆^2- (aq)