JEE Advanced levelOne or more correct optionsDifficulty 3 of 3ce153
For A(g)+B(g)C(g), Kc=10Lmol−1 at a given temperature. Four mixtures are prepared (concentrations in molL−1). For which of them does the net reaction proceed forward?
A[A]=0.20, [B]=0.20, [C]=0.30
B[A]=0.10, [B]=0.50, [C]=0.60
C[A]=0.25, [B]=0.40, [C]=1.00
D[A]=0.05, [B]=0.30, [C]=0.10
Answer: A, D
Qc=[C]/([A][B]) gives 7.5, 12.0, 10.0 and 6.67 for the four mixtures. Forward reaction needs Qc<10, which holds for the first and fourth. The second has Qc>Kc (backward) and the third has Qc=Kc (already at equilibrium).