Friday 17 August 2012


Chemistry A level equilibria problem?

just a bit confused how to do this question....

On heating, X decomposes reversibly according to the equation:

X (g) ↔ Y (g) + Z (g)

This reaction was allowed to reach equilibrium at 2 different temperatures.

(a) When 1.00 moles of X was heated at 200'C in a container of volume 25.0dm3, the equilibrium mixture was found to contain 0.200 mole of Y. Calculate the value of Kc at this temperature.

if anyone can help, much appreciated :)

Best Answer - Chosen by Voters

........................ .X (g) ↔ Y (g) + Z (g)

initially ..............1.00.......0..........0
change...............0.2........0.2....…0.2

At equilibrium .....0.8........0.2.......0.2

concentration.......0.8/25 0.2/25 0.2/25

Kc = [Y] [Z] / [X]

......= {(0.2/25) (0.2/25)} / (0.8 /25)
......= 2.0 x 10^-3

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