What is the equilibrium concentration of each of the substance in the equilibrium when the initial concentration of `ICl` was `0.78 M`?
`2ICl(g) hArr I_(2)(g)+Cl_(2)(g), K_(c)=0.14`

Explanation

Suppose at equilibrium , `[I_(2)] = [Cl_(2)] = x "mol" L^(-1) .` Then
`{:(,2I Cl ,hArr,I_(2)(g),+,Cl_(2)(g)), ("Intial conc." ,0*78 "M",,0,,0), ("At eqm.",0*78 - 2 x,,x,,x):}`
` K_(c) = ([I_(2)][Cl_(2)])/([ICl]^(2)) :. 0*14 = (x xx x )/(0*78 - 2x)^(2) `
or ` x^(2) = 0* 14 (0* 78 - 2x)^(2) or x/(0*78-2x) = sqrt(0*14) = 0*374 `
or `x = 0*292 - 0*748 or 1*748 x = 0* 291 or x = 0* 167`
Hence, at equilibrium , ` [I_(2) ] = [Cl_(2)] = 0*167 "M", [ICl ] = 0* 78 - 2 xx 0* 167 "M" = 0*446 "M"`