Question

Methanol is prepared industrially from synthesis gas (CO and H2). CO(g) + 2H2(g) ⇌ CH3OH(g); ΔH° = -21.7 kcal Would the fraction of methanol obtained at equilibrium be increased by raising the temperature? Explain.

Answer 1

We have been given a reaction for which H is -21.7kCal. A negative change in enthalpy of implies the exothermic nature of the reaction. This means heat is being released in the reaction.

When any change in the conditions take place, the equilibrium of the reaction is disturbed. This condition is governed by Le Chatelier's principle.According to it, If a dynamic equilibrium is disturbed by changing the conditions, the position of equilibrium moves to counteract the change.

In case of any increase in temperature, the reaction will move in the direction which reduces the temperature and restores equilibrium. Since exothermic reactions release heat and increase temperature in the forward direction, the backward or reverse reaction takes prominence since it is an endothermic reaction and consumes heat to reduce temperature. Hence the fraction of methanol will decrease by increasing the temperature as the reaction proceeds in bacward direction.

Summary: Fraction of methannol obtained at equilibrium is reduced by raising the temperature. the explanation can be given using Le Chatelier's principle as stated above.