Question

Write the molecular formulae of all the compounds that can be formed by the combination of the following ions ${\mathrm{Cu}}^{2+},{\mathrm{Na}}^{+},{\mathrm{Fe}}^{3+},{\mathrm{Cl}}^{–},{{\mathrm{SO}}_4}^{2-},{{\mathrm{PO}}_4}^{3-}$

Answer 1

Step 1: Molecular formula:

• “A molecular formula that gives the total number of atoms of each element in each molecule of a substance.”

Step 2: Given ions:

• ${\mathrm{Cu}}^{2+},{\mathrm{Na}}^{+},{\mathrm{Fe}}^{3+},{\mathrm{Cl}}^{–},{{\mathrm{SO}}_4}^{2-},{{\mathrm{PO}}_4}^{3-}$

Step 3: Criss-cross method:

• “In this method, the numerical value of each of the ion charges is crossed over to become the subscript of the other ion.”

Step 4: Formation of compounds:

• The formation of compounds via the criss-cross method is given below:

1. Compounds of Copper:

2. Compounds of Sodium:

3. Compounds of Iron: