AP Chem Le Chatelier Principle
36 flashcards covering AP Chem Le Chatelier Principle for the AP-CHEMISTRY Unit 7 section.
Le Chatelier's Principle is a fundamental concept in AP Chemistry that describes how a system at equilibrium responds to changes in concentration, temperature, and pressure. According to the College Board's AP Chemistry Curriculum Framework, understanding this principle is essential for predicting the direction of shifts in chemical reactions and is a key element of Unit 7, which focuses on equilibrium.
On practice exams and competency assessments, questions related to Le Chatelier's Principle often present scenarios where students must predict the effect of specific changes on a given equilibrium system. Common traps include misinterpreting the direction of the shift or overlooking the impact of temperature changes on equilibrium constants. Students may also confuse the effects of concentration changes with those of pressure changes in gaseous systems, leading to incorrect conclusions.
A practical tip to keep in mind is that while shifts in equilibrium can be predicted, the extent of the shift and the new concentrations at equilibrium require careful calculation, which is often overlooked in exam settings.
Terms (36)
- 01
What does Le Chatelier's Principle state about equilibrium systems?
Le Chatelier's Principle states that if an external change is applied to a system at equilibrium, the system will adjust to counteract that change and restore a new equilibrium (College Board CED for AP Chemistry).
- 02
How does increasing the concentration of a reactant affect an equilibrium system?
Increasing the concentration of a reactant will shift the equilibrium position to the right, favoring the formation of products (College Board CED for AP Chemistry).
- 03
What is the effect of decreasing the temperature on an exothermic reaction at equilibrium?
Decreasing the temperature of an exothermic reaction will shift the equilibrium position to the right, favoring the production of more heat and products (College Board CED for AP Chemistry).
- 04
When pressure is increased in a gaseous equilibrium, what is the expected shift?
Increasing the pressure will shift the equilibrium position toward the side with fewer moles of gas (College Board CED for AP Chemistry).
- 05
What happens to an equilibrium system when a catalyst is added?
Adding a catalyst does not affect the position of equilibrium; it only increases the rate at which equilibrium is reached (College Board CED for AP Chemistry).
- 06
How does the addition of an inert gas at constant volume affect equilibrium?
Adding an inert gas at constant volume does not change the partial pressures of the reactants or products and therefore has no effect on the position of equilibrium (College Board CED for AP Chemistry).
- 07
What is the effect of increasing temperature on an endothermic reaction at equilibrium?
Increasing the temperature of an endothermic reaction will shift the equilibrium position to the right, favoring the formation of products (College Board CED for AP Chemistry).
- 08
If a system at equilibrium is subjected to a decrease in volume, what will occur?
A decrease in volume will shift the equilibrium position toward the side with fewer moles of gas (College Board CED for AP Chemistry).
- 09
What is the impact of removing a product from an equilibrium system?
Removing a product will shift the equilibrium position to the right, favoring the formation of more products (College Board CED for AP Chemistry).
- 10
In a reaction where heat is a product, what happens if the temperature is decreased?
Decreasing the temperature will shift the equilibrium position to the left, favoring the formation of reactants (College Board CED for AP Chemistry).
- 11
How does the addition of a reactant affect the equilibrium position?
Adding a reactant will shift the equilibrium position to the right, favoring the formation of products (College Board CED for AP Chemistry).
- 12
What is the relationship between equilibrium constant and temperature?
The equilibrium constant (K) is temperature-dependent; changes in temperature can alter the value of K for a given reaction (College Board CED for AP Chemistry).
- 13
What is the effect of dilution on a system at equilibrium?
Dilution decreases the concentration of all species in a solution, which may shift the equilibrium position depending on the reaction stoichiometry (College Board CED for AP Chemistry).
- 14
How does the presence of a common ion affect solubility equilibrium?
The presence of a common ion will shift the solubility equilibrium to the left, decreasing the solubility of the salt (College Board CED for AP Chemistry).
- 15
What is the effect of increasing the concentration of products on an equilibrium system?
Increasing the concentration of products will shift the equilibrium position to the left, favoring the formation of reactants (College Board CED for AP Chemistry).
- 16
When is a system considered to be at equilibrium?
A system is at equilibrium when the rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant (College Board CED for AP Chemistry).
- 17
What does a shift to the left in an equilibrium reaction indicate?
A shift to the left indicates that the reaction is favoring the formation of reactants over products (College Board CED for AP Chemistry).
- 18
How does temperature affect the equilibrium constant for an exothermic reaction?
For an exothermic reaction, increasing temperature decreases the equilibrium constant (K) (College Board CED for AP Chemistry).
- 19
What is the effect of adding a product to a system at equilibrium?
Adding a product will shift the equilibrium position to the left, favoring the formation of reactants (College Board CED for AP Chemistry).
- 20
How does a change in pressure affect an equilibrium involving solids?
Changes in pressure have no effect on the position of equilibrium for reactions involving solids, as solids do not contribute to the pressure (College Board CED for AP Chemistry).
- 21
What is the principle behind Le Chatelier's Principle?
Le Chatelier's Principle is based on the idea that systems at equilibrium will respond to changes in conditions to counteract those changes and restore equilibrium (College Board CED for AP Chemistry).
- 22
What happens to the equilibrium position when a reactant is added?
Adding a reactant will shift the equilibrium position to the right, favoring the formation of products (College Board CED for AP Chemistry).
- 23
How does increasing the temperature affect an exothermic reaction?
Increasing the temperature of an exothermic reaction shifts the equilibrium position to the left, favoring the formation of reactants (College Board CED for AP Chemistry).
- 24
What occurs when a system at equilibrium is subjected to a change in concentration?
The system will shift in a direction that counteracts the change in concentration to re-establish equilibrium (College Board CED for AP Chemistry).
- 25
What is the impact of a catalyst on an equilibrium reaction?
A catalyst speeds up the rate of both the forward and reverse reactions equally, helping the system reach equilibrium faster without changing the equilibrium position (College Board CED for AP Chemistry).
- 26
How does the addition of a non-reactive gas affect an equilibrium system?
Adding a non-reactive gas at constant volume does not change the concentrations of the reactants or products and thus does not affect the equilibrium position (College Board CED for AP Chemistry).
- 27
What does it mean for a reaction to be at dynamic equilibrium?
Dynamic equilibrium means that the forward and reverse reactions continue to occur at equal rates, resulting in constant concentrations of reactants and products (College Board CED for AP Chemistry).
- 28
What is the effect of increasing the volume of a gas-phase equilibrium?
Increasing the volume will shift the equilibrium position toward the side with more moles of gas (College Board CED for AP Chemistry).
- 29
How does the addition of heat affect an endothermic reaction at equilibrium?
Adding heat to an endothermic reaction shifts the equilibrium position to the right, favoring the formation of products (College Board CED for AP Chemistry).
- 30
What happens to the equilibrium constant if a reaction is reversed?
If a reaction is reversed, the equilibrium constant becomes the reciprocal of the original constant (K = 1/K') (College Board CED for AP Chemistry).
- 31
What is the result of a shift in equilibrium to the right?
A shift to the right indicates that the formation of products is favored over reactants (College Board CED for AP Chemistry).
- 32
How does an increase in pressure affect a reaction with equal moles of gas on both sides?
An increase in pressure has no effect on the position of equilibrium if there are equal moles of gas on both sides of the reaction (College Board CED for AP Chemistry).
- 33
What is the effect of temperature on the equilibrium constant for an endothermic reaction?
For an endothermic reaction, increasing the temperature increases the equilibrium constant (K) (College Board CED for AP Chemistry).
- 34
How does the addition of a reactant affect the equilibrium constant?
The addition of a reactant does not change the value of the equilibrium constant; it only shifts the position of equilibrium (College Board CED for AP Chemistry).
- 35
What is the impact of decreasing temperature on an endothermic reaction?
Decreasing the temperature will shift the equilibrium position to the left, favoring the formation of reactants (College Board CED for AP Chemistry).
- 36
What is the effect of a change in concentration on a gaseous equilibrium?
A change in concentration will shift the equilibrium position in a direction that counteracts the change, either to the right or left (College Board CED for AP Chemistry).