Question

Find the formula mass of the compound, then divide the individual element total by the total mass-move the decimal over two to change it to percentage C2H5NBr

Answer 1

Find the molar massesof each element in the periodic table:

$\begin{gathered} C=12g\times2=24g \\ H=1g\times5=5g \\ N=14g\times1=14g \\ Br=80g\times1=80g \\ C_2H_5NBr=123g \end{gathered}$

Divide each mass by the total mass to find the percentage mass of each element:

$\begin{gathered} C=\frac{24g}{123g}=0.195=19.5\% \\ H=\frac{5g}{123g}=0.041=4.1\% \\ N=\frac{14g}{123g}=0.114=11.4\% \\ Br=\frac{80g}{123g}=0.65=65\% \end{gathered}$