equilibrium chemistry q help....???

2017-04-25 2:09 pm

When one mole of ammonia is heated to a given temp, 50 per cent dissociates and the following equilibrium is established.
NH3==0.5N2 + 1.5H2
What is the total number of moles of gas present in this mixture?
A) 1.5
B) 2.0
C) 2.5
D) 3.0
I keep getting A and the answer is D pls help.

回答 (1)

micatkie

2017-04-25 2:47 pm

NH₃ ⇌ 0.5 N₂ + 1.5 H₂
Mole ratio in reaction NH₃ : N₂ : H₂ = 1 : 0.5 : 1.5

Initial number of moles of NH₃ = 1 mol
Initial number of moles of N₂ = 0 mol
Initial number of moles of H₂ = 0 mol

Number of moles of NH₃ dissociated = (1 mol) × 50% = 0.5 mol
Number of moles of N₂ produced = (0.5 mol) × 0.5 = 0.25 mol
Number of moles of H₂ produced = (0.5 mol) × 1.5 = 0.75 mol

Number of moles of NH₃ at equilibrium = (1 - 0.5 mol) = 0.5 mol
Number of moles of N₂ produced = (0.5 mol) × 0.5 = 0.25 mol
Number of moles of H₂ produced = (0.5 mol) × 1.5 = 0.75 mol

Total number of moles of gas in the mixture = (0.5 + 0.25 + 0.75) mol = 1.5 mol

The answer is A, but NOT D.

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