312.1 moles H₂ (4 sig.figs. based on -9551Kj value given).
Explanation:
Given N₂(g) + 3H₂(g) => 2NH₃(g); ΔH° = -91.8Kj*
One mole of H₂ consumed will give -91.8Kj/3 = -30.6Kj/mole (exothermic)
moles H₂ consumed that gives -9551Kj (exothermic) = -9551Kj/-30.6Kj/mole H₂
= 312.124183moles H₂ (calculator answer) ≅ 312.1 moles H₂ (4 sig.figs. based on -9551Kj value given).
*Note: The ∆H° = -91.8 kJ/mol units should be only 'Kj' as the heat flow value applies to substances with three different coefficient values in the standard equation. FYI :-)
