AB_(2) " dissociates as " : AB_(2) (g) hArr AB (g) + B (g). If the intial pressure is 500 mm of Hg and the total pressure at equilibriumis 700 mm 0f Hg, calculate K_(p)for the reaction.

AB_(2) " dissociates as " : AB_(2) (g) hArr AB (g) + B (g). If the int

1.	AB_(2) " dissociates as " : AB_(2) (g) hArr AB (g) + B (g). If the intial pressure is 500 mm of Hg and the total pressure at equilibriumis 700 mm 0f Hg, calculate K_(p)for the reaction.
Answer» Solution :After dissociation , suppose the decrease in the pressure of `AB_(2)` at equilibrium is p MM. Then ` {:(,AB_(2) (G),hArr,AB (g),+,B (g)),(" Intial pressure",500 mm,,0,,0),(" Pressures at eqm.",(500-)p " mm", ,p" mm",,p " mm"):} ` `:. " Total pressure at equilibrium " = 500 - p + p+ p = 500 + p" mm"` `500 + p = 700" (Given) " or p= 200 " mm"` Hence , at equilibrium `p _(AB_(2)) = 500 - 200 = 300 " mm" , 200 " mm ", p_(B) = 200 mm ` `:. K_(p) = (p_(AB) XX p_(B))/p_(AB_(2)) = (200 xx 200)/300 = 1333MM` Note. With RESPECT to standard state pressure of 1 bar , i.e., 0987 atm , i.e., 750 mm, `K_(p) = (1333)/750=0178.`