CH4 (g)+ H2O (g) --->/<---- 3H2 + CO
Use Le Chateliers Principle to explain what will happen to the number of moles of hydrogen at equilibrium when
a) CO is removed
b) Water Vapor is removed
c) Methane is added
d) CO is added
e) Pressure is increased by adding argon gas, but the partial pressure of the reactants and products do not change.
f) The pressure is decreased by opening a valve to a second reaction vessel, which lowers the partial pressures of the reactants and products.
g) The temperature is increased.
Methane is added
To answer these questions, let's first understand what Le Chatelier's Principle is. Le Chatelier's Principle states that when a system at equilibrium is subjected to a change in temperature, pressure, or concentration of reactants/products, the system will react in a way that tends to counteract or minimize the effect of that change.
a) When CO is removed:
According to the balanced equation, the formation of CO is the forward reaction. By removing CO, we are essentially decreasing the concentration of a product. According to Le Chatelier's Principle, the system will shift in the direction that produces more CO to counteract the change. Therefore, the reaction will shift to the right, leading to an increase in the number of moles of hydrogen.
b) When water vapor is removed:
In this case, we are decreasing the concentration of a reactant (H2O). According to Le Chatelier's Principle, the system will shift in the direction that replenishes the reactant to counteract the change. Since water vapor is on the reactant side, the reaction will shift to the left, resulting in a decrease in the number of moles of hydrogen.
c) When methane is added:
Adding methane (CH4) will increase the concentration of a reactant. According to Le Chatelier's Principle, the system will shift in the direction that consumes the excess reactant to counteract the change. In this case, the reaction will shift to the right, leading to an increase in the number of moles of hydrogen.
d) When CO is added:
Adding CO will increase the concentration of a reactant. According to Le Chatelier's Principle, the system will shift in the direction that consumes the excess reactant to counteract the change. Since CO is on the reactant side, the reaction will shift to the right, resulting in an increase in the number of moles of hydrogen.
e) When pressure is increased by adding argon gas:
Increasing the pressure without changing the partial pressures of the reactants and products does not cause a change in the concentration of reactants or products. Therefore, according to Le Chatelier's Principle, the system will not shift in any particular direction. Hence, the number of moles of hydrogen will remain the same.
f) When the pressure is decreased by opening a valve to a second reaction vessel:
Lowering the pressure decreases the total pressure of the system, which affects the equilibrium position. According to Le Chatelier's Principle, the system will shift in the direction that increases the total pressure. If reactants or products have fewer moles of gas compared to the other side (reactants or products), the reaction will shift in that direction to increase the total pressure. So, in this case, if there are fewer moles of gas on the product side, the reaction will shift to the right, increasing the number of moles of hydrogen.
g) When the temperature is increased:
An increase in temperature affects the equilibrium position depending on whether the reaction is exothermic or endothermic. In this case, if the reaction is exothermic (releasing heat), an increase in temperature will cause the reaction to shift in the reverse direction to absorb the excess heat. Considering that the forward reaction releases heat, it is exothermic. Therefore, an increase in temperature will shift the reaction to the left, resulting in a decrease in the number of moles of hydrogen.
By considering Le Chatelier's Principle and the changes described for each scenario, you can predict the effects on the number of moles of hydrogen at equilibrium.