Question

10- Describe Le Chatelier’s Principle

11-Consider the following reaction at equilibrium. What effect will reducing some C have on the system? Why?

            CO2(g) + C(graphite) ⇌ 2 CO(g)

12- Consider the following reaction at equilibrium. What effect will increasing the volume of the reaction mixture have on the system? Why?

            CuS(s) + O2(g) ⇌ Cu(s) + SO2(g)

13-Consider the following reaction at equilibrium. What effect will reducing the volume of the reaction mixture have on the system? Why?

            Xe(g) + 2 F2(g) → XeF4(g)

Answer 1

10. Le Chatelier's principle also called Chatelier's principle or "The Equilibrium Law", can be used to predict the effect of a change in conditions on a chemical equilibrium. The principle is named after Henry Louis Le Chatelier and sometimes Karl Ferdinand Braun who discovered it independently. It can be stated as:
When any system at equilibrium is subjected to change in concentration, temperature, volumes, or pressure, then the system readjusts itself to (partially) counteract the effect of the applied change and a new equilibrium is established.
In other words, whenever a system in equilibrium is disturbed the system will adjust itself in such a way that the effect of the change will be nullified.

Effect of change in concentration:
Changing the concentration of a chemical will shift the equilibrium to the side that would reduce that change in concentration. The chemical system will attempt to partially oppose the change affected to the original state of equilibrium. In turn, the rate of reaction, extent, and yield of products will be altered corresponding to the impact on the system.

Effect of change in temperature:
The effect of changing the temperature in the equilibrium can be made clear by 1) incorporating heat as either a reactant or a product, and 2) assuming that an increase in temperature increases the heat content of a system. When the reaction is exothermic (ΔH is negative, puts energy out), heat is included as a product, and, when the reaction is endothermic (ΔH is positive, takes energy in), heat is included as a reactant. Hence, whether increasing or decreasing the temperature would favor the forward or the reverse reaction can be determined by applying the same principle as with concentration changes.

Effect of change in pressure:
The equilibrium concentrations of the products and reactants do not directly depend on the total pressure of the system but they do depend on the partial pressures of the products and reactants.
Changing total pressure by adding an inert gas at constant volume does not affect the equilibrium concentrations .
Changing total pressure by changing the volume of the system changes the partial pressures of the products and reactants and can affect the equilibrium concentrations.

Effect of change in volume:
Changing the volume of the system changes the partial pressures of the products and reactants and can affect the equilibrium concentrations. With a pressure increase due to a decrease in volume, the side of the equilibrium with fewer moles is more favorable and with a pressure decrease due to an increase in volume, the side with more moles is more favorable. There is no effect on a reaction where the number of moles of gas is the same on each side of the chemical equation.

11.The reaction will shift to the right in the direction of products because As the concentration of C is increased, the frequency of successful collisions of that reactant would increase also, allowing for an increase in forward reaction, and generation of the product.

12.Increase volume means equilibrium shifts to side where there are less moles of gas. Both sides have 1 mole of gas. Solids have no effect on equilibrium.

13.The number of moles of gas on the left-hand side and the number of moles of gas on the right-hand side. When the volume of the system is changed, the partial pressures of the gases change. If we were to decrease pressure by increasing volume, the equilibrium of the above reaction will shift to the left, because the reactant side has a greater number of moles than does the product side.