Answer to Question #169081 in Chemistry for Tom

Question

What mass of hydrogen must be reacted to produce 5,540kJ of energy based on the following reaction: 3H2+N2=2NH3 DeltaH=-2709J

Answer 1

Solution:

The balanced thermochemical equation:

3H₂ + N₂ → 2NH₃, △H = -2709 J

The equivalences for this thermochemical equation are:

3 mol H₂ ⇔ 1 mol N₂ ⇔ 2 mol NH₃ ⇔ Q = 2709 J

Use the thermochemical equation to determine the moles of hydrogen (H₂):

5540 J × (3 mol H₂ / 2709 J) = 6.1351 mol H₂

Mass of H₂ = Moles of H₂ × Molar mass of H₂

Molar mass of P is 2.016 g mol^-1.

Hence,

Mass of H₂ = 6.1351 mol × 2.016 g mol^-1 = 12.3684 g = 12.37 g

Mass of H₂ = 12.37 g

Answer: 12.37 grams of hydrogen (H₂) must be reacted to produce 5.540 kJ of energy.