What is the equilibirum 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
`2ICl(g) hArr I_(2)(g)+Cl_(2)(g)`
`{:("Initial",0.78 M,,0,0),("At eqm.",0.78-2x,,x,x):}`
`K_(c )=([I_(2)][C_(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 x`
`rArr 1.748-x=0.292`
or `x=0.167`
Hence, at equilibrium, `[I_(2)]=[Cl_(2)]=0.167 M`,
`[ICl]=0.78-2xx0.167 M=0.446 M`