A 2.0 , g sample containing MnO_2 is treated | vedclass

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(A) $MnO_2 + 4HCl \longrightarrow MnCl_2 + Cl_2 + 2H_2O$$Cl_2 + 2KI \longrightarrow 2KCl + I_2$$I_2 + 2Na_2S_2O_3 \longrightarrow 2NaI + Na_2S_4O_6$Eq

Vedclass · Accepted Answer

$13$

Vedclass · Answer

(A) $MnO_2 + 4HCl \longrightarrow MnCl_2 + Cl_2 + 2H_2O$$Cl_2 + 2KI \longrightarrow 2KCl + I_2$$I_2 + 2Na_2S_2O_3 \longrightarrow 2NaI + Na_2S_4O_6$Equivalents of $MnO_2 = 	ext{Equivalents of } Cl_2 = 	ext{Equivalents of } I_2 = 	ext{Equivalents of } Na_2S_2O_3$Equivalents of $Na_2S_2O_3 = 	ext{Molarity} 	imes 	ext{Volume (L)} 	imes n	ext{-factor} = 0.1 	imes 0.060 	imes 1 = 6 	imes 10^{-3} \, eq$Since the $n$-factor of $MnO_2$ in the reaction $MnO_2 \longrightarrow Mn^{2+}$ is $2$,moles of $MnO_2 = \frac{6 	imes 10^{-3}}{2} = 3 	imes 10^{-3} \, mol$Molar mass of $MnO_2 = 55 + 2 	imes 16 = 87 \, g/mol$Mass of $MnO_2 = 3 	imes 10^{-3} 	imes 87 = 0.261 \, g$$\% \, MnO_2 = \frac{0.261}{2.0} 	imes 100 = 13.05 \, \%$Nearest integer is $13$.

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