Problem: Consider the following reaction occurring at 298 K: N2O(g) + NO2(g) ⇌ 3 NO(g)If a reaction mixture contains only N2O and NO2 at partial pressures of 1.0 atm each, the reaction will be spontaneous until some NO forms in the mixture. What maximum partial pressure of NO builds up before the reaction ceases to be spontaneous?

🤓 Based on our data, we think this question is relevant for Professor Dodson's class at UNR.

FREE Expert Solution

G=G°+RTlnQ

 ΔG < 0 or ΔG = (–); the reaction is spontaneous
• ΔG = 0; the reaction is at equilibrium
• ΔG > 0 or ΔG = (+); the reaction is non-spontaneous

• Q = K; the reaction is at equilibrium
Q < K; the reaction shifts in the forward direction to reach equilibrium (spontaneous in the forward direction)
• Q > K; the reaction shifts in the reverse direction to reach equilibrium

the reaction ceases to be spontaneous → when the reaction reached equilibrium

0=G°+RTlnKG°=-RTlnK


Step 1:

N2O(g) + NO2(g) ⇌ 3 NO(g)

ΔG°=ΔG°f, prod-ΔG°f, react

ΔG°=(3 mol NO)87.6 kJ1 mol NO           -(1 mol NO2)103.7 kJ1 mol NO2+(1 mol NO2)51.3 kJ1 mol NO2

ΔG° = 107.8 kJ

ΔG°=107.8 kJ×103 J1 kJ

ΔG° = 107800 J



Step 2:

G°=-RTlnK107800 Jmol=-(8.314Jmol·K)(298 K)lnK107800 Jmol-(2477.572Jmol)=-(2477.572Jmol)lnK-(2477.572Jmol)ln Kln=-43.51lnK=e-43.51

K = 1.2697x10-19


Step 3:

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Problem Details

Consider the following reaction occurring at 298 K: N2O(g) + NO2(g) ⇌ 3 NO(g)

If a reaction mixture contains only N2O and NO2 at partial pressures of 1.0 atm each, the reaction will be spontaneous until some NO forms in the mixture. What maximum partial pressure of NO builds up before the reaction ceases to be spontaneous?

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Based on our data, we think this problem is relevant for Professor Dodson's class at UNR.