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For the reaction below, describe the temperature and pressure conditions that would produce the highest yield for the forward reaction. Explain your answer in terms of Le Châtelier’s principle.

CO (g) + 2 H2 (g) Two arrows stacked on top of each other. The top arrow points to the right. The bottom arrow points to the left. CH3OH (g) deltaH = -90.7 kJ/mol



Answer :

quasarJose

Answer:

Explanation:

The complete reaction equation is given as:

                         CO + 2H₂ ⇄ CH₃OH                       ΔH = -90.7kJmol⁻¹  

From the reaction equation, we know that:

  • the reactants are in gaseous phases. Carbon monoxide(CO) and Hydrogen gas are gases.
  • the reaction is an exothermic reaction beceause ΔH is negative. Heat would be liberated to the surroundings in this kind of reaction.

According to Le Chatelier's principle, we know that "if any of the conditions of a system in equilibrium is changed, the system will adjust itself in order to annul the effect of the change".

For pressure changes:  

A change in pressure affects only equilibrium involving a gas or gases. An increase in pressure will shift the position of equilibrium to the side having smaller volume(or mole) and vice versa.

                          CO       +       2H₂ ⇄      CH₃OH

                          3 moles of gases        1 mole of gas

An increase in pressure will favor the production of more methanol since we have 3 moles of gas on the left hand side and just one mole of gas on the right hand side.

For temperature changes:

A rise in temperature shifts equilibrium to the direction that absorbs heat and vice versa. Since the reaction is exothermic in the forward reaction, a rise in temperature will favor the forward reaction. This would lead to the production of more methanol gas. A decrease in temperature will favor the backward reaction.