Q. In acid medium Zn reduces nitrate ion to ${NH}_{4}^{+}$ ion according to the reaction $Zn + {NO}_{3}$ ${Zn}^{2 +} + {NH}_{4}^{+} + H_{2}O\ \ \ \$(unbalanced) How many moles of HCl are required to teduce half a mole of ${NaNO}_{3}$ completely? Assume the availability of sufficient Zn.
A) 5
B) 4
C) 3
D) 2
Explanation
(a)
$\therefore 4Zn + {NO}_{3}^{-} + 10H^{+} \longrightarrow 4{Zn}^{2 +} + {NH}_{4}^{+} + 3H_{2}O$(Net equation)
$4Zn + {NO}_{3}^{-} + 10HCl \longrightarrow 4{Zn}^{2 +} + {NH}_{4}^{+} + 5{Cl}_{2} + 3H_{2}O$
$\because 1\$mole of ${NO}_{3}^{-}$ (0r ${NaNO}_{3})$ is reduced by
=10 moles of HCl
$\therefore\frac{1}{2}$ mole of ${No}_{3}^{-}$ will be reduced by
= $10 \times \frac{1}{2}\$moles of HCl
= 5 moles of HCl
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.