InterviewSolution
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InterviewSolution
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i. The initial pressure of `PCl_(5)` present in one litre vessel at `200 K` is `2` atm. At equilibrium the pressure increases to `3` atm with temperature increasing to `250`. The percentage dissociation of `PCl_(5)` at equilibrium isA. `30%`B. `60%`C. `0.2%`D. `20%` |
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Answer» Correct Answer - D i. First method: Pressure at `200 K=2 "atm"` Pressure at `250 K=P "atm"` Using relation, `P_(1)/T_(1)=P_(2)/T_(2)rArr P/250=2/200` `:. P=2.5 "atm"` `{:(,PCl_(5),hArr,PCl_(3),+,Cl_(2)),("Initial",a,,0,,0),("At equilibrium",a-alpha,,alpha,,alpha),("Total moles" =a+alpha,,,,,):}` `("Intial mole")/("moles at equilibrium")= (("Intial pressure after"),("change of temperature"))/("Equilibrium pressure")` `(a)/(a+alpha)=2.5/3 rArr alpha=1/5 a` Therefore, `%` of `PCl_(5)` dissociated `=alpha/axx100` `=a/(5xxa)xx100=20%` Secondethod: Using relation: `alpha=(T_(2)P_(2)-T_(2)P_(1))/(T_(2)P_(1))` `=(200xx3-250xx2)/(250xx2)=(600-500)/(500)` `alpha=1/5` `% "of" alpha=1/5xx100=20%` |
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