Chapter 3, Problem ISP

Aqueous solutions of ammonium sulfide and mercury(II) nitrate react and a precipitate forms.

1. (a) Write the overall balanced chemical equation and indicate the state (aq) or (s) for each compound.
2. (b) Name each product.
3. (c) Write the complete ionic equation.
4. (d) Write the net ionic equation.

Interpretation Introduction

Interpretation:

Aqueous solutions of ammonium sulfide and mercury(II) nitrate react forms precipitate. The balanced chemical equation has to be written.

Concept introduction:

Balanced Chemical equation:

A balanced chemical equation is an equation which contains same elements in same number on both the sides (reactant and product side) of the chemical equation thereby obeying the law of conservation of mass.

Balancing the equation:

• There is a Law for conversion of mass in a chemical reaction i.e., the mass of total amount of the product should be equal to the total mass of the reactants.
• First write the skeletal reaction from the given information.
• Then count the number of atoms of each element in reactants as well as products.
• Place suitable coefficients in front of reactants as well as products until the number of atoms on each side (reactants and products) becomes equal.

Explanation of Solution

The reaction is given below,

    Ammonium sulfide and mercury(II) nitrate react forms precipitate.

Balance the equation,

    ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{S(aq) + Hg(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{NH}}_{\text{4}}{\text{NO}}_{\text{3}}\text{(aq) + HgS(s)}$

While balancing the equation, the subscripts cannot be altered but coefficients can be changed. There are two nitrogen atoms in the left side of the reaction and one nitrogen atom in the right side of the reaction, therefore two molecules of ammonium nitrate are added to the right side of the reaction Now, the balanced equation is given below.

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{S(aq) + Hg(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{2 NH}}_{\text{4}}{\text{NO}}_{\text{3}}\text{(aq) + HgS(s)}$

Interpretation Introduction

Interpretation:

The product has to be named.

Explanation of Solution

The reaction is given below,

    Ammonium sulfide and mercury(II) nitrate react forms precipitate.

The chemical reaction is given below,

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{S(aq) + Hg(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{2 NH}}_{\text{4}}{\text{NO}}_{\text{3}}\text{(aq) + HgS(s)}$

Name of the reactants: Ammonium sulfide and mercury(II) nitrate.

Name of the products: Ammonium nitrate and mercury sulfide.

The product name is given.

Interpretation Introduction

Interpretation:

The complete ionic equation has to be written for the aqueous solutions of ammonium sulfide and mercury(II) nitrate react forms precipitate.

Concept introduction:

Net ionic Equation:

The net ionic equation shows only those chemical species that actually undergo chemical change.  The ions that do not change during the chemical reaction are called spectator ions.  These spectator ions are not shown in net ionic equation.

Explanation of Solution

The reaction is given below,

    Ammonium sulfide and mercury(II) nitrate react forms precipitate.

The chemical reaction is given below,

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{S(aq) + Hg(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{2 NH}}_{\text{4}}{\text{NO}}_{\text{3}}\text{(aq) + HgS(s)}$

The complete ionic equation is given below,

    ${\text{2NH}}_{\text{4}}^{\text{+}}\text{+}{\text{S}}^{\text{2-}}\text{(aq)}\text{+}{\text{Hg}}^{\text{2+}}\text{(aq)}\text{+}{\text{2NO}}_{\text{3}}^{\text{-}}\text{(aq)}\to {\text{2NH}}_{\text{4}}^{\text{+}}{\text{+ 2NO}}_{\text{3}}^{\text{-}}\text{(aq) + HgS(s)}$

Interpretation Introduction

Interpretation:

The net ionic equation has to be written for the aqueous solutions of ammonium sulfide and mercury(II) nitrate react forms precipitate.

Concept introduction:

Net ionic Equation:

The net ionic equation shows only those chemical species that actually undergo chemical change.  The ions that do not change during the chemical reaction are called spectator ions.  These spectator ions are not shown in net ionic equation.

Explanation of Solution

The reaction is given below,

    Ammonium sulfide and mercury(II) nitrate react forms precipitate.

The chemical reaction is given below,

  ${{\text{(NH}}_{\text{4}}\text{)}}_{\text{2}}{\text{S(aq) + Hg(NO}}_{\text{3}}{\text{)}}_{\text{2}}\text{(aq) }\to {\text{2 NH}}_{\text{4}}{\text{NO}}_{\text{3}}\text{(aq) + HgS(s)}$

The complete equation is given below,

    ${\text{2NH}}_{\text{4}}^{\text{+}}\text{+}{\text{S}}^{\text{2-}}\text{(aq)}\text{+}{\text{Hg}}^{\text{2+}}\text{(aq)}\text{+}{\text{2NO}}_{\text{3}}^{\text{-}}\text{(aq)}\to {\text{2NH}}_{\text{4}}^{\text{+}}{\text{+ 2NO}}_{\text{3}}^{\text{-}}\text{(aq) + HgS(s)}$

Remove all the spectator ions from the reaction. The net ionic equation is given below,

    ${\text{S}}^{\text{2-}}\text{(aq)}\text{+}{\text{Hg}}^{\text{2+}}\text{(aq)}\to \text{ HgS(s)}$