Calculate the formula unit mass of ${\mathrm{CaCl}}_2$.

• Formula unit mass is the sum of atomic masses of all atoms present in the formula unit of a compound.it is used for substances whose constituent elements are ions.
• Formula unit mass of ${\mathrm{CaCl}}_2$ (Calcium chloride) = (1 x Atomic mass of $\mathrm{Ca}$))+ (2 x Atomic mass of $\mathrm{Cl}$)

$$\begin{gathered} =(1\times 40\mathrm{u})+(2\times 35.5\mathrm{u}) \\ =111\mathrm{u} \end{gathered}$$

• Thus, the formula mass of Calcium Chloride is 111u