Question

a) Balance the following molecular equations for these reactions.
b) write the ionic equation for the reactions.
c)write the net ionic equation for the reactions.

a) La2(CO3)3 (s) + HCl (aq) --> LaCl3 (aq) + CO2 (g) + H2O (l)

b) K2S2 (aq) + Bi(NO3)3 --> Bi2(S2)3 (s) + KNO3 (aq)

Answer 1

In the balanced equation all the ionic compounds are represented using molecular formula. In ionic equation the ionic compounds in solution are represented by ions. Solids and gases are represented as it is. In net ionic equation the unchanged ionic species on both sides of reaction (spectator ions) are cancelled. The net ionic equation shows only those species which are involved in reaction.

Ans a)

Reaction of La₂(CO₃)₃ with HCl is the acid-base neutralization reaction. Balanced equation can be written as follows:

La₂(CO₃)₃ (s) + 6HCl (aq) --> 2LaCl₃ (aq) + 3CO₂ (g) + 3H₂O (l)

The ionic equation of the above reaction can be written as follows:

La₂(CO₃)₃ (s) + 6H⁺(aq)    + 6Cl^- (aq) --> 2La³⁺(aq) + 6Cl^- (aq) + 3CO₂ (g) + 3H₂O (l)

The net ionic equation of the above reaction can be written as follows:

La₂(CO₃)₃ (s) + 6H⁺(aq)    --> 2La³⁺(aq) + 3CO₂ (g) + 3H₂O (l)

Ans b)

Balanced equation of reaction of K₂S₂ with Bi(NO₃)₃ can be written as follows:

3K₂S₂ (aq) + 2Bi(NO₃)₃(aq) --> Bi₂(S₂)₃ (s) + 6KNO₃ (aq)

The ionic equation of the above reaction can be written as follows:

6K⁺(aq)   + 3S₂^2- (aq)   +   2Bi³⁺(aq)   +   6(NO₃)^-(aq)   -->     Bi₂(S₂)₃ (s) +   6K⁺(aq)   +   6(NO₃)^- (aq)

The net ionic equation of the above reaction can be written as follows:

3S₂^2- (aq)   +    2Bi³⁺(aq)    -->     Bi₂(S₂)₃ (s)