State and explain Le Chatelier's principle. Apply the principle to the following equilibrium:
State and explain Le Chatelier's principle. Apply the principle to the following equilibrium:
- The different factors that affect the chemical equilibrium are the concentration of the reactants or products, temperature and pressure.
- Le Chatelier's principle explains the effect of various factors on the equilibrium.
- Le Chatelier's principle: According to this principle, when a system at equilibrium is subjected to a constraint or change, the position of the equilibrium shifts in the direction that opposes the constraints.
- Effect of concentration: When the concentration of the reactants or products at equilibrium is changed, the reaction proceeds in the direction in which the effect of change in concentration is compensated.
Example- In the reaction , if the concentration of hydrogen or iodine at equilibrium increases then the reaction proceeds in the forward direction. While the addition of at equilibrium results in the shift of equilibrium in the backward direction.
- Effect of pressure: According to Boyle's law, , where P is pressure and V is volume and according to Avogadro's law , Where V is volume and n is the number of moles of the gas.
Therefore, the effect of pressure is applicable only to the reactions that are accompanied by a change in the number of moles (change in volume). When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas. When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas.
Example- In the reaction , a decrease in pressure favours the forward reaction because the number of moles of products is more than that of the reactants.
- Effect of Temperature: Most chemical reactions are associated with the absorption or evolution of heat. An increase in temperature makes the reaction proceeds in that direction in which more heat is absorbed. Similarly, a decrease in temperature allows the reaction to take place in a direction associated with the release of heat energy.
For example- if the temperature is increased, the position of equilibrium moves in the direction of the endothermic reaction. if the temperature is reduced, the position of equilibrium moves in the direction of the exothermic reaction.
- The given reaction is :
This is an endothermic reaction (reactions in which heat is absorbed). Since the reaction is accompanied by absorption of heat energy, an increase in temperature favours the forward direction, which means that for all endothermic reactions, high temperature is the most favourable condition.
- The different factors that affect the chemical equilibrium are the concentration of the reactants or products, temperature and pressure.
- Le Chatelier's principle explains the effect of various factors on the equilibrium.
- Le Chatelier's principle: According to this principle, when a system at equilibrium is subjected to a constraint or change, the position of the equilibrium shifts in the direction that opposes the constraints.
- Effect of concentration: When the concentration of the reactants or products at equilibrium is changed, the reaction proceeds in the direction in which the effect of change in concentration is compensated.
Example- In the reaction , if the concentration of hydrogen or iodine at equilibrium increases then the reaction proceeds in the forward direction. While the addition of at equilibrium results in the shift of equilibrium in the backward direction.
- Effect of pressure: According to Boyle's law, , where P is pressure and V is volume and according to Avogadro's law , Where V is volume and n is the number of moles of the gas.
Therefore, the effect of pressure is applicable only to the reactions that are accompanied by a change in the number of moles (change in volume). When there is an increase in pressure, the equilibrium will shift towards the side of the reaction with fewer moles of gas. When there is a decrease in pressure, the equilibrium will shift towards the side of the reaction with more moles of gas.
Example- In the reaction , a decrease in pressure favours the forward reaction because the number of moles of products is more than that of the reactants.
- Effect of Temperature: Most chemical reactions are associated with the absorption or evolution of heat. An increase in temperature makes the reaction proceeds in that direction in which more heat is absorbed. Similarly, a decrease in temperature allows the reaction to take place in a direction associated with the release of heat energy.
For example- if the temperature is increased, the position of equilibrium moves in the direction of the endothermic reaction. if the temperature is reduced, the position of equilibrium moves in the direction of the exothermic reaction.
- The given reaction is :
This is an endothermic reaction (reactions in which heat is absorbed). Since the reaction is accompanied by absorption of heat energy, an increase in temperature favours the forward direction, which means that for all endothermic reactions, high temperature is the most favourable condition.
