Ta có:
\(n_{C2H4Br2}=\frac{4,7}{188}=0,025\left(mol\right)\)
\(PTHH:C_2H_4+Br_2\rightarrow C_2H_4Br_2\)
\(\Rightarrow n_{C2H4}=n_{C2H4Br2}=0,025\left(mol\right)\)
\(\Rightarrow m_{C2H4}=0,025.28=0,7\left(mol\right)\)
\(n_{hh}=\frac{2,8}{22,4}=0,125\left(mol\right)\)
\(n_{CH2}=0,125-0,025=0,1\left(mol\right)\Rightarrow m_{CH2}=0,1.14=1,4\left(g\right)\)
\(\Rightarrow\left\{{}\begin{matrix}\%m_{CH2}=\frac{1,4}{1,4+0,7}.100\%=66,67\%\\\%m_{C2H4}=100\%-66,67\%=33,33\%\end{matrix}\right.\)