Question

Calculate the molecular mass of ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$.

Answer 1

The total atomic masses of all the elements that make up a compound's molecular structure make up its molecular mass.

$$\begin{gathered} \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{H}=1\mathrm{g} \\ \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{O}=16\mathrm{g} \\ \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Cu}=63.5\mathrm{g} \\ \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{S}=32\mathrm{g} \\ \mathrm{Molecular}\mathrm{mass}\mathrm{of}{\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}=\mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Cu}+\mathrm{atomic}\mathrm{mass}\mathrm{of}\mathrm{S}+(9\times \mathrm{atomic}\mathrm{mass}\mathrm{of}\mathrm{O})+(10\times \mathrm{atomic}\mathrm{mass}\mathrm{of}\mathrm{H}) \\ =63.5+32+9\times 16+10\times 1 \\ =249.5\mathrm{gm}/\mathrm{mole} \end{gathered}$$

Hence, the molecular mass of ${\mathrm{CuSO}}_4.5{\mathrm{H}}_2\mathrm{O}$ is 249.5 g/mol.