For the reaction, 2 A g + B g ⇌ C g + D g ; K c = 1 0 1 2 . If the initial moles of A, B, C and D are 2 , 1 , 7 and 3 moles respectively in 1 L vessel, what is the equilibrium concentration of A?

Step-by-step solution

2 A g + B g ⇌ C g + D g Initial moles 2 1 7 3 At equilibrium 2 - 2 x 1 - x 7 + x 3 + x ∴ Due to very high value of K, we can assume that reactant almost gets converted into products, so 1 - x = y 2 - 2 x = 2 y ⇒ x ∼ 1 ∴ 1 0 1 2 = C D A 2 B 1 0 1 2 = 8 × 4 2 y 2 y y 3 = 8 × 1 0 - 1 2 ⇒ y = 2 × 1 0 - 4 ∴ Equilibrium concentration of A = 2 y = 2 × 2 × 1 0 - 4 = 4 × 1 0 - 4