Deslocamento de Equilíbrio - Princípio de Le Chatelier

Summary

In this lesson, we explore Le Chatelier's Principle, which explains how chemical equilibria shift when external forces are applied. The video covers three key factors that affect equilibrium: concentration, pressure, and temperature. An increase in concentration of reactants or products shifts the equilibrium to balance it. Pressure changes influence equilibria in gaseous reactions, with shifts occurring toward the side with fewer gas molecules. Temperature changes affect the direction of equilibrium based on whether the reaction is exothermic or endothermic. The lesson emphasizes how these factors impact equilibrium and the constant value associated with it.

Takeaways

• 😀 Le Chatelier's Principle states that if a system at equilibrium is disturbed, it will shift to minimize the disturbance and restore a new equilibrium.
• 😀 Changes in concentration of reactants or products cause the equilibrium to shift towards consuming the added substance or replenishing the removed one.
• 😀 Adding CO₂ to a system shifts the equilibrium to the right (favoring the forward reaction) to consume the added CO₂.
• 😀 Removing CO from a system causes the equilibrium to shift to the right to replace the removed CO.
• 😀 Increasing pressure on a gaseous equilibrium shifts the equilibrium towards the side with fewer gas molecules to reduce the pressure.
• 😀 When the number of gas molecules is equal on both sides of the reaction, pressure changes have no effect on the equilibrium.
• 😀 Temperature is the only factor that affects the equilibrium constant (K) of a reaction.
• 😀 An increase in temperature shifts the equilibrium towards the endothermic direction, while a decrease in temperature shifts it toward the exothermic direction.
• 😀 In an exothermic reaction, increasing temperature shifts the equilibrium to the left (absorbing heat), while decreasing temperature shifts it to the right (releasing heat).
• 😀 The equilibrium constant remains unchanged with changes in concentration or pressure, but it changes when temperature changes.
• 😀 Understanding how a system responds to changes in concentration, pressure, or temperature is essential to predict the behavior of chemical equilibria.

Q & A

What is Le Chatelier's Principle?

Le Chatelier's Principle states that if a system at equilibrium is subjected to a disturbance, it will shift in a direction that minimizes the effect of the disturbance, until a new equilibrium is established.

What factors can affect the equilibrium of a chemical reaction?

The three main factors that can affect the equilibrium of a chemical reaction are concentration, pressure, and temperature.

How does the concentration of reactants or products affect equilibrium?

An increase in the concentration of either reactants or products will cause the system to shift in a direction that consumes the added substance, thus re-establishing equilibrium. For example, adding CO2 to a reaction will shift the equilibrium towards the products.

Why is the concentration of solids or liquids not considered in the equilibrium constant?

The concentrations of solids and liquids are not included in the equilibrium constant because their concentrations do not change during the reaction and are considered constant.

What happens to a reaction when pressure is increased in a gas-phase equilibrium?

When pressure is increased in a gas-phase equilibrium, the system will shift towards the side with fewer gas molecules to reduce the total pressure. This is in accordance with Le Chatelier's Principle.

How does an increase in pressure affect a reaction with an equal number of gas molecules on both sides?

If a reaction has the same number of gas molecules on both sides, increasing the pressure will have no effect on the equilibrium, as there is no imbalance in the number of molecules.

What is the effect of temperature on equilibrium?

Temperature affects the equilibrium by shifting the reaction towards either the exothermic or the endothermic direction. Increasing the temperature favors the endothermic reaction, while decreasing the temperature favors the exothermic reaction.

How does an increase in temperature affect an exothermic reaction?

For an exothermic reaction, increasing the temperature shifts the equilibrium towards the reverse, endothermic direction, as the system tries to absorb the excess heat.

What is the difference between concentration/pressure changes and temperature changes in terms of equilibrium constant?

Changes in concentration or pressure do not affect the value of the equilibrium constant. However, changes in temperature do alter the equilibrium constant, as the system adjusts to a new equilibrium based on the temperature change.

What happens to the equilibrium constant if a reaction experiences a temperature change?

When the temperature of a system in equilibrium changes, the value of the equilibrium constant changes as well. The system will adjust to a new equilibrium that corresponds to the new temperature.