Đáp án:

\(\begin{array}{l} m_{KMnO_4}=63,2\ g.\end{array}\)

Giải thích các bước giải:

\(\begin{array}{l} a,\ PTHH:\ 2KMnO_4\xrightarrow{t^o} K_2MnO_4+MnO_2+O_2\ (1)\\ 3Fe+2O_2\xrightarrow{t^o} Fe_3O_4\ (2)\\ b,\ n_{Fe_3O_4}=\dfrac{23,2}{232}=0,1\ mol.\\ Theo\ pt\ (2):\ n_{O_2}=2n_{Fe_3O_4}=0,2\ mol.\\ Theo\ pt\ (1):\ n_{KMnO_4}=2n_{O_2}=0,4\ mol.\\ \Rightarrow m_{KMnO_4}=0,4\times 158=63,2\ g.\end{array}\)

chúc bạn học tốt!

Giải thích các bước giải:

\[\begin{array}{l} \qquad {\kern 1pt} 2KMn{O_4}\xrightarrow{t^\circ}{K_2}Mn{O_4} + Mn{O_2} + {O_2}\\ {\rm{mol}}{\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} \;\;\;0,4{\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} \leftarrow \qquad {\kern 1pt} \qquad {\kern 1pt} \qquad {\kern 1pt} \qquad {\kern 1pt} \;\;0,2\\ \qquad {\kern 1pt} 3Fe + 2{O_2}\xrightarrow{t^\circ}F{e_3}{O_4}\\ {\rm{mol}}\qquad {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} 0,2{\mkern 1mu} {\kern 1pt} {\mkern 1mu} {\kern 1pt} \leftarrow \;\; 0,1\\ {n_{F{e_3}{O_4}}} = \frac{{23,2}}{{232}} = 0,1\;{\rm{mol}} \end{array}\]

Theo PTHH: \[\begin{array}{l}
{n_{KMn{O_4}}} = 0,4\;{\rm{mol}}\\
 \Rightarrow {m_{KMn{O_4}}} = 158 \cdot 0,4 =63,2\;{\rm{gam}}
\end{array}\]