Equimolar concentrations of `H_(2)` and `I_(2)` are heated to equilibrium in a 2 L flask. At equilibrium, the forward and backward rate constants are found to be equal. What percentage of initial concentration of `H_(2)` has reached at equilibrium ?

Options

A. 0.33
B. 0.66
C. `50%`
D. 0.4

Answer

A

Explanation

`{:(,H_(2)(g),+,I_(2)(g),hArr,2HI(g)),("Initial",1 mol,,1 mol,,0),("At eqm.",1-x,,1-x,,2x),("Molar conc.",(1-x)/(2),,(1-x)/(2),,(2x)/(2)mol L^(-1)):}`
`K=((2x)^(2))/((1-x)(1-x))=(4x^(2))/((1-x)^(2))`
But `k_(f)//k=1impliesk=1 :. (2x)/(1-x)=1 ` or `x=1//3`
Percent dissociation `=100//3=33.33%`