Question

The equilibrium constant, Kp, equals 3.40 for the isomerization reaction: cis-2-butene ↔ trans-2-butene. If a flask initially contains 0.250 atm of cis-2-butene and 0.145 atm of trans-2-butene, what is the equilibrium pressure of each gas?

Answer 1

Solution :-

balanced reaction equation

cis-2-butene ↔ trans-2-butene

0.250 atm                 0.145 atm

-x                                +x

0.250-x                      0.145 +x

now lets make the kp equation

Kp =[trans-2-butene]/[cis-2-butene]

3.40 = [0.145+x]/[0.250-x]

3.40 * 0.250-x = 0.145+x

x=0.160 atm

therefore at the equilibrium pressure of the each is as follows

[trans-2-butene ] = 0.145 atm + x = 0.145 atm + 0.160 atm = 0.305 atm

[cis-2-butene ] = 0.250-x = 0.250 atm -0.160 atm = 0.090 atm