Question

3. a) How would you drive the following reaction to the right to form more products: CO(g) + H2O(g) + CO2(g) + H, (g) AH°= -40.3 kJ Ans. b) One of the products is a 'high value substance. Which one, and what is it used for?

Answer 1

a ) CO_(g) + H₂O_(g) ⇌ CO_2(g) + H_2(g)

This reaction is called Water - Gas shift reaction.

The reaction does not change molar totals and therefore the effect of pressure on the reaction is minimal.The equilibrium of this reaction shows a significant temperature dependence and the equilibrium constant decreases with an increase in temperature, that is, higher carbon monoxide conversion is observed at lower temperatures. The water gas shift reaction is a moderately exothermic reversible reaction. Therefore, with increasing temperature the reaction rate increases but the conversion of reactants to products becomes less favorable.This reaction is usually carried out in presence of iron chromate as catalyst.The equilibrium for H₂ production is favored by high moisture content and low temperature for the exothermic reaction. By the removal of product hygrogen,we can shift the reaction towards right side.

Thus we get more products.

b ) The Water-Gas shift reaction is industrially important. It involes the formation of H₂. This reaction provides a source of hydrogen at the expense of carbon monoxide, which is important for the production of high purity hydrogen for use in ammonia synthesis.This reaction can aid in the efficiency of fuel cells by increasing hydrogen production.In the Fischer–Tropsch process, this reaction is one of the most important reactions used to balance the H₂/CO ratio.