Kc Flashcards
(18 cards)
What is the relationship between equilibrium constants and Le Chatelier’s Principle?
Equilibrium constants remain unchanged with concentration changes, but the position of equilibrium shifts according to Le Chatelier’s Principle. Only temperature changes the equilibrium constant.
Why do concentration changes not affect the equilibrium constant?
Concentration changes shift the equilibrium position but do not alter the equilibrium constant, which depends solely on temperature.
How does Le Chatelier’s Principle respond to concentration changes?
It states that equilibrium shifts to counteract concentration changes, either increasing or decreasing reactants or products.
What happens when a substance’s concentration is increased?
The equilibrium shifts to reduce the increase, producing more of the decreased substance.
What is the equilibrium constant?
A numerical value expressing the ratio of product to reactant concentrations at equilibrium at a specific temperature.
Describe the effect of temperature change on the equilibrium constant.
Changing the temperature alters the equilibrium constant, either increasing or decreasing it depending on whether the reaction is endothermic or exothermic.
Explain why the equilibrium position can change without changing the equilibrium constant.
The position of equilibrium can shift due to changes in concentration or pressure, but the equilibrium constant remains unchanged unless the temperature is altered.
Explain the role of the equilibrium constant in maintaining the position of equilibrium.
The equilibrium constant remains constant at a given temperature, and the system shifts to restore this value when disturbed, such as by changing concentrations.
How does changing pressure affect gas systems?
Pressure changes can shift equilibrium but do not change the equilibrium constant; higher pressure favors fewer molecules.
Define the effect of pressure change on the position of equilibrium when the number of molecules on each side is equal.
When the number of molecules on each side of the reaction is equal, changing the pressure has no effect on the position of equilibrium.
Define the term ‘equilibrium constant’ in the context of pressure changes.
The equilibrium constant is a value that remains unchanged when pressure is altered; it only changes with temperature. It represents the ratio of concentrations or partial pressures of products to reactants at equilibrium.
Explain why increasing pressure does not always lead to an increase in Kp in a gas-phase equilibrium.
Because Kp is based on the expression involving partial pressures or mole fractions and total pressure, when these are substituted and simplified, most pressure terms cancel out, leaving Kp unchanged if temperature remains constant.
Define Kp in the context of gas-phase equilibria.
Kp is the equilibrium constant expressed in terms of the partial pressures of the gaseous reactants and products at a constant temperature.
How does the relationship between partial pressure, mole fraction, and total pressure affect the expression for Kp?
Replacing partial pressures with mole fractions multiplied by total pressure simplifies the Kp expression, causing most pressure terms to cancel out, which shows that Kp remains constant if temperature is unchanged.
Explain the significance of the cancellation of most P terms in the Kp expression.
The cancellation indicates that changes in total pressure do not affect the value of Kp at constant temperature, emphasizing that Kp depends only on temperature, not on pressure.
Describe what happens to the position of equilibrium when pressure increases in a gas system, assuming all gases are involved.
The position of equilibrium may shift to the right or left depending on the reaction’s stoichiometry, but this does not necessarily change the value of Kp, which remains constant at a given temperature.
Explain why Kp must stay constant when temperature is unchanged.
Because Kp is temperature-dependent, if the temperature remains constant, the value of Kp must also remain unchanged, regardless of changes in pressure or mole fractions.
Describe how increasing the terms on the top of a reaction quotient affects the position of equilibrium.
Increasing the terms on the top of the reaction quotient increases the mole fractions of molecules on the right-hand side, which shifts the equilibrium position to the right, as predicted by Le Chatelier’s Principle.
