Question

Sodium carbonate (${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$) is an important industrial compound. Calculate its formula mass.

Answer 1

Formula mass:- It is defined as the mass of any chemical formula or compound. In the neutral state of the compound, it is equivalent to molecular mass.

Explanation:-

${\mathrm{Na}}_2{\mathrm{CO}}_3.10{\mathrm{H}}_2\mathrm{O}$ is made up of:-

1. 2 $\mathrm{Na}$-atoms
2. 1 $\mathrm{C}$-atom
3. 3 $\mathrm{O}$-atom
4. 10 ${\mathrm{H}}_2\mathrm{O}$ molecules

Atomic mass of $\mathrm{Na}$-atom = 23u

Atomic mass of $\mathrm{C}$-atom = 12u

Atomic mass of $\mathrm{O}$-atom = 16u

Mass of each ${\mathrm{H}}_2\mathrm{O}$ molecule = 18u

Mass of Sodium carbonate = $2\times \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{Na}\left(23\right)+1\times \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{C}\left(12\right)+3\times \mathrm{Atomic}\mathrm{mass}\mathrm{of}\mathrm{O}\left(16\right)+10\times \mathrm{Mass}\mathrm{of}{\mathrm{H}}_2\mathrm{O}\left(18\right)$

Mass of Sodium carbonate = $(2\times 23)\mathrm{u}+(1\times 12)\mathrm{u}+(3\times 16)\mathrm{u}+(10\times 18)\mathrm{u}$

Mass of sodium carbonate = $286\mathrm{u}$

Hence, formula mass of $N{a}_{\mathit{2}}C{O}_{\mathit{3}}\mathit{.}\mathit{10}{H}_{\mathit{2}}O$ is 286u