3.112_CP - Chemistry: Molecular Nature Of Matter And Change

Question

The study of sulfur-nitrogen compounds is an active area of chemical research, made more so by the discovery in the early 1980s of one such compound that conducts electricity like a metal. The first sulfur-nitrogen compound was prepared in 1835 and serves today as a reactant for preparing many of the others. Mass spectrometry of the compound shows a molar mass of 184.27 g/mol, and analysis shows it to contain 2.288 g of S for every 1.000 g of N. What is its molecular formula?

Step-by-Step Solution

Answer

The molecular formula is S₄N₄.

Finding the moles of S and N

On converting the mass of S & N into moles by multiplication for molar mass reciprocal.

$\begin{array}{l}\mathrm{Moles}\mathrm{of}\mathrm{S}=2.288\mathrm{g}\mathrm{S}\times \frac{1\mathrm{molS}}{32.07\mathrm{g}\mathrm{S}}\\ =0.0713\mathrm{mol}\mathrm{S}\\ \mathrm{Moles}\mathrm{of}\mathrm{N}=1\mathrm{g}\mathrm{N}\times \frac{1\mathrm{mol}\mathrm{N}}{14.01\mathrm{g}\mathrm{N}}\\ =0.0714\mathrm{molN}\end{array}$ 

Finding the molecular formula

The whole number multiple can be derived as,

$\begin{array}{l}=\frac{184.27\mathrm{g}/\mathrm{mol}}{46.08\mathrm{g}/\mathrm{mol}}\\ \mathrm{Whole}\mathrm{number}\mathrm{multiple}=4\end{array}$

On multiplying the subscript of S₁N₁ by 4. The molecular formula can be found as S₄N₄.