NH3 is heated at 15 atm from 270C to 3470C assuming volume constant. The new pressure becomes to atm at equilibrium of the reaction 2NH3⇌N2+3H2 % of mole of NH3 actually decomposed in the reaction is:
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Solution
2NH3
⇌
N2
+
3H2
Initial mole
a
0
0
Moles at eqm.
a−2x
x
3x,Total=a+2x
Pressure of a moles of NH3 at 27oC=15atm Pressure of a moles of NH3 at 347oC =P atm (say) As volume remains constant, P1T1=P2T2 15300=P620 or P=31atm Now at 327oC and constant volume, Pressure ∝ No. of moles ∴31∝a 50αa+2x ∴a+2xa=5031 or x=1962a % of NH3 decompose =2xa×100=2×19a62×1a×100=61.3%