Methanol, CH3OH, is produced on an industrial scale from carbon monoxide and hydrogen. At the temperatures used, gaseous methanol is formed according to the following thermochemical equation:
CO(g)+ 2H2(g) <---> CH3OH(g) �£H = -90Kj
1. State Le Chateliers principle and explain the following:
a)The effect that increasing the pressure will have on the equalibrium yield of menthanol
b) the effect of increasing the temperature will have on the equalibrium yield of menthanol
c) the effect of increasing the temperature will have on the rate of reaction
where appropriate, show clear understanding of how the Le Chatelier's principle applies
I will be happy to critique your thinking on this.
Le Chateliers principle states that If a system in a state of equilibrium is disturbed, it will undergo a change that shifts its equilibrium position in a direction that reduces the effect of the disturbance.
Therefore,
a)If you increase pressure on a gas you decrease the volume (boyles law), the reaction will shift in a direction to the side of the reaction with the fewer moles of gas in order to reduce pressure and bring the system back to equilibrium
Your understanding of Le Chatelier's principle is correct. When the pressure is increased in a system, like the one you described, the equilibrium position will shift in a direction that reduces the effect of the pressure increase.
In this case, by increasing the pressure, you are essentially compressing the gases involved in the reaction. According to Le Chatelier's principle, the system will react in a way that minimizes the impact of the pressure increase.
Looking at the balanced equation for the reaction: CO(g) + 2H2(g) ⇌ CH3OH(g), you can see that there are three moles of gas on the left-hand side of the reaction and one mole of gas on the right-hand side.
Since the reaction shifts in the direction that reduces the effect of the pressure increase, it will favor the side of the reaction with fewer moles of gas. In this case, it will shift towards the right (towards the formation of methanol) to reduce the pressure. This means that increasing the pressure will increase the equilibrium yield of methanol.
Now let's move on to the effect of temperature on the equilibrium yield of methanol. According to Le Chatelier's principle,
b) Increasing the temperature will cause the equilibrium position to shift in a direction that opposes the change. In an exothermic reaction like the one you mentioned, increasing the temperature will cause the reaction to shift in the direction that consumes heat and reduces the temperature increase.
Looking at the thermochemical equation for the formation of methanol: CO(g) + 2H2(g) ⇌ CH3OH(g) ΔH = -90 kJ, you can see that it is exothermic (since ΔH is negative).
When you increase the temperature, the reaction will shift towards the left (towards the reactants) to consume the excess heat and lower the temperature. This means that increasing the temperature will decrease the equilibrium yield of methanol.
Lastly, let's consider the effect of temperature on the rate of reaction.
c) Increasing the temperature generally increases the rate of reaction. This is due to the fact that at higher temperatures, the reactant molecules have more kinetic energy, resulting in more frequent and energetic collisions, leading to a faster rate of reaction.
However, it's important to note that while increasing the temperature may speed up the rate of reaction, it will also affect the equilibrium position. As mentioned earlier, increasing the temperature will shift the equilibrium position towards the reactants (in this case, CO and H2) to consume the excess heat. So even though the rate of reaction may increase, the equilibrium yield of methanol may decrease.
In summary, when considering the impact of pressure and temperature changes on the equilibrium yield of methanol:
a) Increasing the pressure will increase the equilibrium yield of methanol.
b) Increasing the temperature will decrease the equilibrium yield of methanol.
c) Increasing the temperature will generally increase the rate of reaction, but it may also affect the equilibrium yield.