The degree of dissociation of HI at a particular temperature is 0.8. 2M, `16 xx 10^(x)` ml of hypo solution required to neutralise the Iodine present in a equilibrium mixture of a reaction when 2 mole each of `H_(2) and I_(2)` are heated in a closed vessel of 2 lit capacity, then the value of x is

Answer

2

Explanation

`underset(1-alpha)underset(1)(2HI) harr underset((alpha)/(2))underset(0)(H_(2))+underset((alpha)/(2))underset(0)(I_(2))`
`Kc=(alpha^(2))/(4(1-alpha)^(2))=((0.8)^(2))/(4(1-0.8))=4`
`underset(2-x)underset(2)(H_(2))+underset(2-x)underset(2)(I_(2)) harr underset(2x)underset(0)(2HI)`
`K_(c)^(1)=(1)/(Kc)=(4x^(2))/((2-x)^(2))`
`(4x^(2))/((2-x)^(2))=(1)/(4)` or `(2x)/(2-x)=(1)/(2) implies x=(2)/(5)`
Thus `I_(2)` left = `2-(2)/(5)=(8)/(5)` mole = `(8)/(5) xx 2` equivalent
Milli equivalents of `Na_(2)S_(2)O_(3)hyp_(0)` = Meq of `I_(2)` left
`2 xx V=(8)/(5) xx 2 xx 1000`
`V=1600 ml=16 xx 10^(2) ml`
`=16 xx 10^(x) implies x=2`