Q98P - Chemistry: Molecular Nature Of Matter And Change

Question

Many chemical names are similar at first glance. Give the formulas of the species in each set:

1. ammonium ion and ammonia
2. magnesium sulfide, magnesium sulfate, and magnesium sulfate
3. hydrochloric acid, chloric acid, and chlorous acid;
4. cuprous bromide and cupric bromide.

Step-by-Step Solution

Answer

a.  The ammonium ion formula is ${\mathbf{NH}}_{\mathbf{4}}^{\mathbf{+}}$

     Ammonia formula is ${\mathbf{NH}}_{\mathbf{3}}$

b.  Magnesium sulfide  $\mathbf{MgS}$

    Magnesium sulfite ${\mathbf{MgSO}}_{\mathbf{3}}$

    Magnesium sulfate ${\mathbf{MgSO}}_{\mathbf{4}}$

c. Hydrochloric acid  $\mathbf{HCl}$

   Chloric acid  ${\mathbf{HClO}}_{\mathbf{3}}$

    Chlorous acid  ${\mathbf{HClO}}_{\mathbf{4}}$

d. Cuprous bromide  $\mathbf{CuBr}$

    Cupric bromide  ${\mathbf{CuBr}}_{\mathbf{4}}$

Step 1: Ammonia and ammonium ion

Ammonium ion and ammonia are similar except that ammonia is one less hydrogen than ammonium ion.

The ammonium ion formula is ${\mathbf{NH}}_{\mathbf{4}}^{\mathbf{+}}$

Ammonia formula is ${\mathbf{NH}}_{\mathbf{3}}$

Step 2: Sulfide, sulfite and sulfate

They differ in the anion. 

Sulfide is ${\mathbf{S}}^{\mathbf{2}\mathbf{-}}$

Sulfite is ${\mathbf{S}}_{\mathbf{3}}^{\mathbf{2}\mathbf{-}}$

Sulfate is ${\mathbf{S}}_4^{\mathbf{2}\mathbf{-}}$ 

Magnesium sulfide  $\mathbf{MgS}$

Magnesium sulfite ${\mathbf{MgSO}}_{\mathbf{3}}$

Magnesium sulfate ${\mathbf{MgSO}}_4$

Step 3: Hydrochloric acid, chloric acid and chlorous acid

They differ in the number of oxygen atoms.

Hydrochloric acid has no oxygen, Chloric acid has 3 and Chlorous acid has 4.

 

Hydrochloric acid  $\mathbf{HCl}$

Chloric acid  ${\mathbf{HClO}}_{\mathbf{3}}$

Chlorous acid ${\mathbf{HClO}}_{\mathbf{4}}$

Step 4: Cuprous bromide and cupric bromide

They differ in the number of bromides because the charge of the copper of each compound is also different

Cuprous bromide  $\mathbf{CuBr}$

Cupric bromide  ${\mathbf{CuBr}}_{\mathbf{2}}$