JEE Advanced levelOne or more correct optionsDifficulty 3 of 3td219
For the gas-phase isomerisation AB at 300K, ΔG∘=−4.0kJmol−1 (standard pressure 1bar, R=8.314Jmol−1K−1). Select all correct statements.
AK≈1.60
BStarting from pure A, the equilibrium mole fraction of B is about 0.83
CIf Q=PB/PA=10, then ΔG≈+1.74kJmol−1 and the reaction goes in the reverse direction
DAt equilibrium ΔG=ΔG∘=−4.0kJmol−1
Answer: B, C
lnK=4000/(8.314×300)=1.604, so K=4.97; the value 1.60 is lnK, not K. Since K=xB/xA (equal moles), xB=K/(1+K)=0.833. For Q=10, ΔG=−4000+2494.2×ln10=+1743Jmol−1, so the reverse reaction occurs. At equilibrium ΔG=0, not ΔG∘.