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 =CH₃CH₃ = 1/3

or ,mole fraction of  CH₃COCH₃ = 1- (1/3 +1/3)  = 1/3  

For the equation, CH₃COCH₃ <----> CH₃CH₃ + CO

Further, if total pressure at equilibrium = p 

Then, pressure of CO and CH₃CH₃ = p/ 3 and for CH₃COCH₃= p/3

so,  CH₃COCH₃ <----> CH₃CH₃ + 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.