Equilibria Flashcards
What are the two conditions for equilibrium to be established in a reaction?
The forward and backward reactions occur at the same rate.
The concentration of reactants and products remains constant.
In what type of system can equilibrium occur?
A closed system, where reactants and/or products do not come in contact with the surroundings.
What does it mean for equilibrium to be dynamic?
At a microscopic level, the reaction continues as reactants are converted to products and vice versa, but at a macroscopic level, there is no observable change.
What are some properties that remain unchanged at equilibrium on a macroscopic level?
Pressure, color, pH, and concentration.
Does the reaction stop at equilibrium?
No, the reaction continues at the microscopic level, but the rates of forward and backward reactions are equal.
What is physical equilibrium?
It is an equilibrium that involves a change in state (e.g., liquid to gas, gas to liquid) rather than a chemical reaction.
What are the two conditions for physical equilibrium?
The rate of the forward process equals the rate of the backward process.
The volume of liquid remains constant.
In what type of system can physical equilibrium occur?
A closed system.
How is physical equilibrium similar to chemical equilibrium?
Both are dynamic at the microscopic level but appear unchanging at the macroscopic level.
What remains constant at physical equilibrium on a macroscopic level?
Properties such as color.
What is an example of physical equilibrium?
The equilibrium between liquid and gas, where evaporation and condensation occur at the same rate.
What does the equilibrium constant (πΎπ) tell us?
It tells us the ratio of the concentration of products to reactants at equilibrium.
What is the only factor that can change the value of πΎπ
Temperature
What is the general expression for the equilibrium constant for a reaction:
aA+bBβcC+dD?
πΎπ = [C]^c [D]^d/[A]^a [B]^b
What does a large value of πΎπ (e.g., 4.2Γ10^5) indicate?
The concentration of products is much greater than reactants, meaning the forward reaction is favored.
What does a small value of πΎπ (e.g. 6.9Γ10^β4) indicate?
The concentration of reactants is much greater than products, meaning the backward reaction is favored.
What does it mean if πΎπ =1?
There are equal amounts of reactants and products at equilibrium.
How does πΎπ change when the reaction is reversed?
The new equilibrium constant is the reciprocal of the original:
πΎπβ=1/πΎπ
What happens to πΎπ if the reaction equation is multiplied by a factor π?
πΎπ is raised to the power of π so πΎπβ = (πΎπ)^π
How is πΎπ affected when multiple reactions occur consecutively?
The equilibrium constant for the overall reaction is the product of the individual πΎπ values:
πΎπ = πΎπ1 x πΎπ2 x πΎπ3
What is the reaction quotient (π)
It is the ratio of product to reactant concentrations at a given moment, even if the reaction is not at equilibrium.
What does it mean if π<πΎπ?
The forward reaction is favored to reach equilibrium.
What does it mean if π>πΎπ?
The backward reaction is favored to reach equilibrium.
What does it mean if π=πΎπ?
The reaction is at equilibrium.
What does Le ChΓ’telierβs Principle state?
It predicts how a reaction at equilibrium will respond to changes in temperature, pressure, or concentration.
How does an increase in temperature affect an endothermic reaction (Ξπ»>0)?
The equilibrium shifts to the product side (forward reaction is favored).
How does a decrease in temperature affect an endothermic reaction?
The equilibrium shifts to the reactant side (backward reaction is favored).
How does an increase in temperature affect an exothermic reaction (Ξπ»<0)?
The equilibrium shifts to the reactant side (backward reaction is favored).
How does a decrease in temperature affect an exothermic reaction?
The equilibrium shifts to the product side (forward reaction is favored).
What is the only factor that changes the value of πΎπ?
Temperature
How does an increase in pressure affect equilibrium when more gas molecules are on the product side?
The equilibrium shifts to the reactant side (backward reaction is favored).
How does a decrease in pressure affect equilibrium when more gas molecules are on the product side?
The equilibrium shifts to the product side (forward reaction is favored).
How does an increase in pressure affect equilibrium when more gas molecules are on the reactant side?
The equilibrium shifts to the product side (forward reaction is favored).
How does a decrease in pressure affect equilibrium when more gas molecules are on the reactant side?
The equilibrium shifts to the reactant side (backward reaction is favored).
What happens if the concentration of reactants increases or the concentration of products decreases?
The forward reaction is favored, and equilibrium shifts to the product side.
What happens if the concentration of products increases or the concentration of reactants decreases?
The backward reaction is favored, and equilibrium shifts to the reactant side.
How does adding a catalyst affect equilibrium?
It speeds up both the forward and backward reactions but does not change the position of equilibrium.
What is the main effect of a catalyst in a reaction at equilibrium?
Equilibrium is reached faster.
What does the equilibrium constant πΎπ represent in a chemical reaction?
It represents the ratio of the concentrations of products to reactants at equilibrium.
How can the equilibrium constant πΎπ be calculated from equilibrium concentrations?
By substituting the equilibrium concentrations of reactants and products into the equilibrium expression.
What does ICE stand for in calculating equilibrium concentrations?
Initial, Change, and Equilibrium.
What does the change in concentration represent in the ICE table?
The amount of a compound that reacts to reach equilibrium; it is negative for reactants and positive for products.
How do you calculate the equilibrium constant when given initial and equilibrium concentrations?
Write the balanced equation, create the ICE table, calculate the changes in concentration, and then substitute equilibrium concentrations into the equilibrium expression.
What is the algebraic approach when the equilibrium concentrations are not given, but πΎπ and initial concentrations are provided?
Use a variable (e.g., π₯) to represent the change in concentration and solve algebraically.
In reactions where πΎπ is very small (e.g., 10^β3), what assumption can be made about the equilibrium concentrations?
The initial concentration of reactants can be assumed to be equal to the equilibrium concentration of reactants.
What does it mean when ΞπΊβ = 0 for a reaction?
The system has reached equilibrium, and the forward and backward reactions occur at the same rate.
What happens when ΞπΊβ < 0 for a reaction?
The reaction is spontaneous, and the equilibrium favors the products.
What happens when ΞπΊβ>0 for a reaction?
The reaction is non-spontaneous, and the equilibrium favors the reactants.
When ΞπΊβ is very negative, what type of equilibrium mixture is expected?
Mostly products.
What is the relationship between ΞπΊβ and equilibrium?
When ΞπΊβ=0, the system is at equilibrium. If ΞπΊβ < 0, the equilibrium favors products; if ΞπΊβ>0, it favors reactants.
How is the standard Gibbs free energy (ΞπΊβ) related to the equilibrium constant (πΎπ)?
ΞG β=βRTln(πΎπ)?, where R is the universal gas constant and T is the temperature in Kelvin.
What does πΎπ > 1 imply about the equilibrium mixture?
The equilibrium favors the products, meaning there are more products than reactants.
What does πΎπ < 1imply about the equilibrium mixture?
The equilibrium favors the reactants, meaning there are more reactants than products.
What does πΎπ = 1 imply about the equilibrium mixture?
The equilibrium contains similar amounts of products and reactants.
What is the relationship between the rate constants π and πβ² in the equilibrium constant expression?
πΎπ=π/πβ where π is the rate constant for the forward reaction and πβ² is the rate constant for the backward reaction.
How does the equilibrium constant πΎπ relate to the rates of the forward and backward reactions?
The equilibrium constant is determined by the ratio of the rate constants for the forward and backward reactions.
At equilibrium, what is true about the rate of the forward reaction and the rate of the backward reaction?
The rate of the forward reaction is equal to the rate of the backward reaction.
How does the equilibrium constant give information about the relative rates of forward and backward reactions?
The magnitude of πΎπ reflects the ratio of the rate constants, but it doesnβt directly provide information about the individual reaction rates.
