Phản ứng xảy ra:
\(2KI+O_3+H_2O\rightarrow2KOH+I_2+O_2\)
Rắn màu tím đen là I2.
\(\Rightarrow n_{I2}=\frac{38,1}{127,2}==0,15\left(mol\right)=n_{O3}\)
\(n_X=\frac{5,6}{22,4}=0,25\left(mol\right)\)
\(\Rightarrow n_{O2}=0,25-0,15=0,1\left(mol\right)\)
\(\Rightarrow m_X=m_{O2}+m_{O3}=32.0,1+48.0,15=10,4\left(g\right)\)
\(\Rightarrow M_X=\frac{m_X}{n_X}=\frac{10,4}{0,25}=41,6\)
\(\Rightarrow d_{X/H2}=\frac{41,6}{2}=20,8\)