"DESLOCAMENTO" DE EQUILÍBRIO - Princípio de Le Chatelier

Summary

Professor Marcos explains Le Chatelier’s Principle and chemical equilibrium in a dynamic chemistry lesson. He introduces key concepts such as the effects of concentration, temperature, and pressure on chemical equilibrium. The video uses relatable examples, such as the Haber process for ammonia synthesis, to demonstrate how changes in reaction conditions shift the equilibrium. The instructor also incorporates a memorable 'urubu' rule to help students understand the principle's application in a fun and engaging way. Overall, the lesson provides a clear and interactive approach to understanding how equilibrium systems respond to external disturbances.

Takeaways

• 😀 Le Chatelier's Principle states that a system at equilibrium will shift to counteract any external change or disturbance applied to it, aiming to restore equilibrium.
• 😀 Chemical reactions that are reversible can proceed in both the forward and reverse directions simultaneously, forming a dynamic equilibrium.
• 😀 Three main factors can shift the equilibrium: concentration, temperature, and pressure. These are the key components of Le Chatelier’s Principle.
• 😀 The principle involves balancing the concentration of reactants and products. Changing the concentration of one substance will shift the equilibrium to favor the other side.
• 😀 Temperature changes affect equilibrium based on whether the reaction is exothermic or endothermic. An increase in temperature generally favors the endothermic direction.
• 😀 Pressure changes impact gaseous reactions, with the equilibrium shifting toward the side that has fewer gas molecules when pressure is increased.
• 😀 Catalysts and surface area increase the rate at which equilibrium is reached, but they do not affect the position of the equilibrium itself.
• 😀 A reaction like the synthesis of ammonia (from nitrogen and hydrogen) demonstrates how changes in concentration, pressure, and temperature can affect equilibrium.
• 😀 When the concentration of nitrogen is increased in the ammonia synthesis reaction, the system will shift to consume the excess nitrogen and produce more ammonia.
• 😀 Decreasing the concentration of hydrogen in the same reaction will cause the system to shift in the reverse direction to produce more hydrogen.
• 😀 The 'rule of the crow' (regra do urubu) helps determine the direction of equilibrium shifts: increase the concentration of a substance and the equilibrium shifts to favor the products.
• 😀 An increase in pressure will favor the side of the reaction with fewer moles of gas, demonstrating how equilibrium is affected by changes in the system's total pressure.

Q & A

What is Le Chatelier's Principle?

Le Chatelier's Principle states that if a system at equilibrium is disturbed by an external change (like changes in concentration, temperature, or pressure), the system will adjust itself to counteract that change and restore equilibrium.

How does concentration affect chemical equilibrium?

Changes in concentration shift the equilibrium. If you increase the concentration of reactants, the equilibrium will shift towards the products to balance the change. If you increase the concentration of products, the equilibrium shifts towards the reactants.

What mnemonic is used to remember how concentration changes affect equilibrium?

The 'urubu' (vulture) mnemonic is used. It suggests that if you increase the concentration of a reactant, the equilibrium shifts to the product side, and vice versa.

How does temperature affect chemical equilibrium?

Temperature changes affect equilibrium depending on whether the reaction is exothermic or endothermic. Increasing the temperature favors the endothermic reaction (which absorbs heat), and decreasing the temperature favors the exothermic reaction (which releases heat).

What is the role of pressure in shifting equilibrium?

Pressure changes affect equilibrium in reactions involving gases. Increasing the pressure shifts the equilibrium towards the side with fewer gas molecules, while decreasing pressure favors the side with more gas molecules.

How does pressure apply to the Haber process (ammonia synthesis)?

In the Haber process, increasing the pressure favors the formation of ammonia because the reaction produces fewer gas molecules on the product side compared to the reactant side.

What happens when the concentration of nitrogen is increased in the Haber process?

Increasing the concentration of nitrogen (a reactant) will shift the equilibrium towards the product side, favoring the formation of ammonia.

What is the difference between a change in concentration and a change in temperature in terms of their effect on equilibrium?

A change in concentration shifts the equilibrium towards either the reactant or product side depending on whether you add or remove a substance. Temperature changes, however, shift the equilibrium based on whether the reaction is endothermic or exothermic, with increased temperature favoring the endothermic direction.

How does the addition of a catalyst affect equilibrium?

A catalyst does not affect the position of equilibrium; it only speeds up the rate at which equilibrium is reached, making the system attain equilibrium more quickly.

Why does increasing pressure in a system favor the side with fewer gas molecules?

Increasing pressure compresses the system, and the equilibrium shifts to favor the side with fewer gas molecules in order to reduce the overall volume and counteract the increase in pressure.