The vapour pressure of two miscible liquids `(A)` and `(B)` are `300` and `500 mm` of `Hg` respectively. In a flask `10` mole of `(A)` is mixed with `12` mole of (B). However, as soon as `(B)` is added, `(A)` starts polymerising into a completely insoluble solid. The polymerisation follows first-order kinetics. After `100` minute, `0.525` mole of a solute is dissolved whivh arrests the polymerisation completely. The final vapour pressure of the solution is `400 mm` of `Hg`. Estimate the rate constant of the polymerisation reaction. Assume negligible volume change on mixing and polymerisation and ideal behaviour for the final solution.

Answer

`1.0XX10^(-4)`

Explanation

Let` "x= Number of moles of A left unpolymerised till solute is dissolved."`
`P_("total")=X_(B)P_(B)^(0)+X_(A)P_(A)^(0)`
`400=(12)/(12+x+0.525)xx500(x)/(12+x+0.525)xx300`
`"x=9.9"`
For first order reaction
`K=(+1.303)/(t)"log"(10)/(99.9)`
`K=1.0xx10^(4)" min"^(-1)`