Chemical Equilibrium Quiz

Podcast

Play an AI-generated podcast conversation about this lesson

Questions and Answers

At what temperature does the equilibrium lie heavily to the right, resulting in a dark brown color?

373 K (correct)

273 K

323 K

400 K

What does a reaction quotient Qc value of 8.0 indicate in relation to Kc?

The reaction will move to the right to establish equilibrium. (correct)

There is no change expected in the reaction.

The reaction will move to the left to establish equilibrium.

The reaction is already at equilibrium.

What color change occurs when starting with only N2O4 at 323 K?

The color fluctuates between shades

The color becomes darker (correct)

The color remains colorless

The color becomes lighter

What is the equilibrium constant Kc for the reaction at 25°C given the concentrations of gases?

4.64 × 10−3 Signup and view all the answers

Which of the following statements about chemical equilibrium is true?

Concentrations of reactants and products remain constant at equilibrium. Signup and view all the answers

What does a Kc value significantly less than 1 indicate about the reaction's equilibrium position?

Equilibrium lies to the left Signup and view all the answers

When calculating Kc, which substances are included in the expression?

Only gaseous and aqueous species. Signup and view all the answers

If the value of Kc is 57.0, what does it imply about the reaction at 700 K?

The reaction favors the formation of products at equilibrium. Signup and view all the answers

If Kc is represented as [C]c [D]d / [A]a [B]b, what does the subscript 'c' refer to?

Concentrations in molarity Signup and view all the answers

Which of the following is NOT a characteristic of dynamic equilibrium?

One reactant will eventually be completely consumed. Signup and view all the answers

What is the preferred method for defining the equilibrium constant Kp in a gas reaction?

Using partial pressures Signup and view all the answers

What does the term Δn represent in the equation related to Kp and Kc?

Change in the number of moles of gas Signup and view all the answers

Which condition will affect the value of Kc?

Change in temperature. Signup and view all the answers

How are Kc and Kp related?

Kp can be calculated from Kc using temperature. Signup and view all the answers

What can be concluded about the equilibrium when only starting with NO2 at 323 K?

It will result in the formation of N2O4 Signup and view all the answers

What is the primary role of equilibrium constants Kc and Kp?

They provide the ratio of products to reactants at equilibrium. Signup and view all the answers

What is the relationship between Kp and Kc for the equilibrium reaction involving gases?

Kp = Kc (RT) Signup and view all the answers

In the equilibrium expression for the reaction CaCO3(s) ⇌ CaO(s) + CO2(g), which species is included in Kc?

CO2 Signup and view all the answers

What does a large value of Kc (e.g., $2.4 imes 10^{47}$) indicate about a reaction's equilibrium position?

The equilibrium lies to the right side. Signup and view all the answers

What should be excluded when writing the equilibrium expression?

Pure liquids Signup and view all the answers

How do you express the equilibrium constant Kc for the reaction 2 H2(g) + O2(g) ⇌ 2 H2O(g)?

Kc = [H2O]^2 / ([H2]^2[O2]) Signup and view all the answers

Which of the following describes heterogeneous equilibria?

Reactants and products are in different phases. Signup and view all the answers

What does a small Kc value (e.g., $4.2 imes 10^{-48}$) imply about a chemical equilibrium?

The reaction favors the reactants. Signup and view all the answers

What does the concentration formula indicate for a pure liquid in a chemical reaction?

It is constant throughout the reaction. Signup and view all the answers

What is the condition necessary for a chemical system to achieve dynamic equilibrium?

The process must be reversible and a closed system. Signup and view all the answers

Which statement accurately describes dynamic equilibrium?

The rates of forward and reverse reactions are equal. Signup and view all the answers

How does the concept of chemical equilibrium answer 'how far' does a reaction proceed?

It shows the concentrations of reactants and products remain constant. Signup and view all the answers

What occurs when a reaction reaches an equilibrium state?

The rates of forward and reverse reactions become equal. Signup and view all the answers

In the example of N2O4 and NO2, what does the observation of color indicate at equilibrium?

The reaction mixture reflects the equilibrium state where both species exist. Signup and view all the answers

What happens to the equilibrium position when a reversible reaction starts with excess reactants?

It can achieve the same equilibrium mixture as starting with products. Signup and view all the answers

What substance color indicates N2O4 in an equilibrium reaction with NO2?

Colorless, indicating a higher concentration of N2O4. Signup and view all the answers

What are the implications of a chemical reaction not going to completion?

It suggests that reverse reactions occur and an equilibrium is established. Signup and view all the answers

Study Notes

Chemical Equilibrium 1

Chemical equilibrium is the state where the concentrations of reactants and products remain constant.
In this state, the forward and reverse reactions occur at equal rates, meaning there is no net change in the amounts of reactants or products.
Equilibrium is only applicable to reversible reactions, meaning a reaction could go in either direction.
Kinetics (how fast) is different than equilibrium (how far), as kinetics questions how quickly a reaction occurs, whereas equilibrium focuses on the final position of the reaction.

Dynamic Equilibrium

Dynamic equilibrium in a reaction occurs when the rates of the forward reactions and the reverse reaction are equal.
At this point, the reaction appears to stop but the forward and reverse reactions continue.
The forward reaction creates products; the reverse reaction recreates reactants.
The rates of the forward and reverse reactions are equal at equilibrium, but the amounts of reactants and products do not have to be equal.

Equilibrium Expressions

Equilibrium constants (K) describe the relationship between the concentrations of reactants and products at equilibrium.
For a general reaction aA + bB ⇌ cC + dD, the equilibrium constant Kc is defined as: Kc = [C]^c[D]^d / [A]^a[B]^b
The subscript 'c' denotes the use of concentrations (molarities).
This expression is only applicable when the reactants and products are liquid, or aqueous.

Equilibrium Constant Kp

When dealing with gases, it's easier to measure partial pressures, hence a different expression for the equilibrium constant, Kp.
Kp = (P_C)^c(P_D)^d / (P_A)^a(P_B)^b
Equilibrium constant Kp is used when the reactants and products are gases.

Relating Kc and Kp

Using the ideal gas law, the relationship between Kc and Kp is given by the following expression:
Kp = Kc(RT)^Δn , where Δn is the change in the number of moles of gas between products and reactants.

Heterogeneous Equilibria

In homogeneous equilibria, all reactants and products are in the same phase.
In heterogeneous equilibria, reactants and products are in different phases.
Pure liquids and solids are omitted from equilibrium expressions.
For example, in the reaction CaCO₃(s)⇌CaO(s) +CO₂(g), only the concentration of CO₂ is included in the equilibrium expression.

Using the Equilibrium Expression

The reaction quotient (Q) is used to predict the direction of a reaction when it is not at equilibrium.
If Q < Kc, the reaction will proceed to the right (towards products).
If Q > Kc, the reaction will proceed to the left (towards reactants).
If Q = Kc, the reaction is at equilibrium.

Studying That Suits You

Use AI to generate personalized quizzes and flashcards to suit your learning preferences.

Description

Test your knowledge on chemical equilibrium concepts including dynamic equilibrium and the distinction between kinetics and equilibrium. Assess your understanding of reversible reactions and their characteristics. This quiz will help reinforce your grasp on essential chemical principles.