Q29 of 73 Page 224

Describe the effect of:

a) addition of H2


b) addition of CH3OH


c) removal of CO


d) removal of CH3OH


on the equilibrium of the reaction:


2H2(g) + CO (g) ⇌CH3OH (g)

According to Le Chatelier’s principle, if in a reaction in equilibrium, the concentration of any reactant is increased, the equilibrium shifts in the forward reaction. On the other hand, if the concentration of any product is increased, the equilibrium shifts in the backward direction. The reverse happens if the concentrations are decreased.


For the given reaction,


2H2(g) + CO (g) ⇌CH3OH (g)


a) If the addition of H2 is taking place, it means the concentration of reactant is increasing. According to Le Chatelier’s principle, the equilibrium shifts in the forward direction.


b) If the addition of CH3OH is taking place, it means the concentration of product is increasing. According to Le Chatelier’s principle, the equilibrium shifts in the backward direction.


c) If the removal of CO is taking place, it means the concentration of reactant is decreasing, the equilibrium shifts in the backward direction. According to Le Chatelier’s principle, the equilibrium shifts in the backward direction.


d) If the removal of CH3OH is taking place, it means the concentration of product is decreasing, the equilibrium shifts in the forward direction. According to Le Chatelier’s principle, the equilibrium shifts in the forward direction.


More from this chapter

All 73 →
27

The equilibrium constant for the following reaction is 1.6 ×105 at 1024K

H2(g) + Br2(g) ⇌ 2HBr(g)


Find the equilibrium pressure of all gases if 10.0 bar of HBr is introduced into a sealed container at 1024K.

 28

Dihydrogen gas is obtained from natural gas by partial oxidation with steam as per following endothermic reaction:

CH4 (g) + H2O (g) ⇌ CO (g) + 3H2 (g)


A. Write as expression for Kpfor the above reaction.


B. How will the values of Kpand composition of equilibrium mixture be affected by


(i) increasing the pressure


(ii) increasing the temperature


(iii) using a catalyst?

 30

At 473 K, equilibrium constant Kcfor decomposition of phosphorus pentachloride, PCl5 is 8.3 ×10-3. If decomposition is depicted as,

PCl5 (g) ⇌ PCl3 (g) + Cl2 (g)


= 124.0 kJ mol–1


A. write an expression for Kcfor the reaction.


B. what is the value of Kcfor the reverse reaction at the same temperature?


C. what would be the effect on Kc if (i) more PCl5 is added (ii) pressure is increased?


(iii) Is the temperature increased?

 31

Dihydrogen gas used in Haber’s process is produced by reacting methane from natural gas with high-temperature steam. The first stage of two-stage reaction involves the formation of CO and H2. In the second stage, CO formed in the first stage is reacted with more steam in water gas shift reaction,

CO (g) + H2O (g) ⇌ CO2 (g) + H2 (g)


If a reaction vessel at 400°C is charged with an equimolar mixture of CO and steam such that CO H2O p = p = 4.0 bar, what will be the partial pressure of H2 at equilibrium? Kp= 10.1 at 400°C