CH3COCH3 = CH3CH3 + CO initial pressure of CH3COCH3 is 100mm when equilibrium is established mole fraction of CO is 1/3 hence Kp is

( ans= 50 mm )

Dear Student,

At equilibrium, mole fractions are same so,

Mole fraction of CO =CH_{3}CH_{3} = 1/3

or ,mole fraction of CH_{3}COCH_{3} = 1- (1/3 +1/3) = 1/3

For the equation, CH_{3}COCH_{3} <----> CH_{3}CH_{3} + CO

Further, if total pressure at equilibrium = p

Then, pressure of CO and CH_{3}CH_{3} = p/ 3 and for CH_{3}COCH_{3}= p/3

so, CH_{3}COCH_{3} <----> CH_{3}CH_{3} + CO

Initially, 100 mm.......... .. 0 ..............0

At eqb,. (100-x)mm ....... x..................x

Here, x = p/3 ---eq.1

also, 100- x = p/3 ---eq.2

Adding the two eq. we get,

100 = 2p/3

Or, 2p = 300

p = 150 mm

The answer must be 150mm. There is no other way to solve it.

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