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2.0 mol of PCl5 is taken in a 4.0 L rigid vessel and allowed to reach…

Question

2.0 mol of PCl5 is taken in a 4.0 L rigid vessel and allowed to reach equilibrium for the reaction PCl5(g) <=> PCl3(g) + Cl2(g), for which Kc = 0.040 mol L^-1 at the working temperature. Calculate the percentage dissociation of PCl5 at equilibrium. Give the answer as a percentage rounded to two decimal places.

✓ Verified answer: 24.57checked by our engine — not a guess

Step-by-step solution

Initial concentration = 2.0/4.0 = 0.5 M.

Let x M dissociate.

Kc = x*x/(0.5 - x) = 0.040.
Solving the quadratic x^2 + 0.04x - 0.02 = 0 gives x = 0.12283 M (positive root).
Percentage dissociation = x/0.5 * 100 = 0.12283/0.5 * 100 = 24.57%.

Final answer24.57

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