For 2A(g) B(g) + C(g) , Kc = 0.0625 at 300 K. If 0.8 mol A is placed in a 2 L vessel with 0.1 mol B , what is [C] at equ

Practice question

Question

For 2A(g) <=> B(g) + C(g) , Kc = 0.0625 at 300 K. If 0.8 mol A is placed in a 2 L vessel with 0.1 mol B , what is [C] at equilibrium?

Options

Choose one · Correct answer highlighted

0.05 M Correct 0.1 M 0.025 M 0.2 M

Explanation

Initial: [A] = (0.8/2) = 0.4 M , [B] = (0.1/2) = 0.05 M , [C] = 0 . Let x = [C] , [A] = 0.4 - 2x , [B] = 0.05 + x . Kc = ([B][C]/[A]²) = ((0.05 + x)x/(0.4 - 2x)²) = 0.0625 . Solving, (0.05 + x)x = 0.0625 (0.4 - 2x)² , test x = 0.05 : (0.05 + 0.05) × 0.05 = 0.005 , 0.0625 × (0.4 - 0.1)² = 0.005625 (close), x ≈ 0.05 M .

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