JEE Advanced levelSingle correct optionDifficulty 3 of 3ce049
Methanol is made from the gas-phase equilibrium CO(g)+2HX2(g)CHX3OH(g) at constant temperature. If the total pressure of the equilibrium mixture is doubled (by compression), the new equilibrium mole fractions satisfy: the value of x(CHX3OH)/[x(CO)x(HX2)2] becomes
A2 times its original value
B1/4 of its original value
Cthe same as its original value
D4 times its original value
Answer: D
With pi=xiP, Kp=xMP/(xCOP⋅xHX22P2)=xCOxHX22xM⋅P−2. So the mole-fraction ratio equals KpP2. Doubling P at fixed Kp multiplies it by 22=4.