JEE Main 2019 — Chemistry Physical Chemistry

$${\text{N}}_{2}(g)+3{H}_{2}(g)\rightarrow 2N{H}_{3}(g)$$N2​(g)+3H2​(g)→2NH3​(g)

$$\frac{\text{moles of }{N}_{2}}{\text{stoichiometry of }{\text{N}}_{2}}\neq \frac{\text{mole of }{\text{H}}_{2}}{\text{stoichiometry of }{\text{H}}_{2}}$$stoichiometry of N2​moles of N2​​=stoichiometry of H2​mole of H2​​

Whose ratio is less called limiting reagent.

(a) mole of ${N}_{2}=\frac{28}{28}=1$N2​=2828​=1

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${N}_{2}=\frac{1}{1}=1$N2​=11​=1

mole of ${H}_{2}=\frac{6}{2}=3$H2​=26​=3

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${H}_{2}=\frac{3}{3}=1$H2​=33​=1

there is no limiting reagent.

(b) mole of ${N}_{2}=\frac{35}{28}=1.25$N2​=2835​=1.25

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${N}_{2}=\frac{1.25}{1}$N2​=11.25​ limiting reagent

mole of ${H}_{2}=\frac{8}{2}=4$H2​=28​=4

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${H}_{2}=\frac{4}{3}=1.33$H2​=34​=1.33

(c) mole of ${N}_{2}=\frac{56}{28}=2$N2​=2856​=2

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${N}_{2}=\frac{2}{1}=2$N2​=12​=2

mole of ${H}_{2}=\frac{10}{2}=5$H2​=210​=5

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${H}_{2}=\frac{5}{3}=1.66$H2​=35​=1.66 limiting reagent.

(d) mole of ${N}_{2}=\frac{14}{28}=0.5$N2​=2814​=0.5

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${N}_{2}=\frac{0.5}{1}=0.5$N2​=10.5​=0.5 limiting reagent

mole of ${H}_{2}=\frac{4}{2}=2$H2​=24​=2

$\frac{moles}{stiochiometry}$stiochiometrymoles​ ratio of ${H}_{2}=\frac{2}{3}=1.66$H2​=32​=1.66

$\therefore$∴ Answer is $(3)$(3) .