Textbook Question
The equilibrium constant for the dissociation of molecular iodine, I2(g) ⇌ 2 I(g), at 800 K is Kc = 3.1 × 10–5. (a) Which species predominates at equilibrium I2 or I?
Ch.15 - Chemical Equilibrium
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement177
- Ch.2 - Atoms, Molecules, and Ions231
- Ch.3 - Chemical Reactions and Reaction Stoichiometry216
- Ch.4 - Reactions in Aqueous Solution189
- Ch.5 - Thermochemistry175
- Ch.6 - Electronic Structure of Atoms168
- Ch.7 - Periodic Properties of the Elements150
- Ch.8 - Basic Concepts of Chemical Bonding177
- Ch.9 - Molecular Geometry and Bonding Theories200
- Ch.10 - Gases179
- Ch.11 - Liquids and Intermolecular Forces113
- Ch.12 - Solids and Modern Materials154
- Ch.13 - Properties of Solutions157
- Ch.14 - Chemical Kinetics199
- Ch.15 - Chemical Equilibrium128
- Ch.16 - Acid-Base Equilibria164
- Ch.17 - Additional Aspects of Aqueous Equilibria163
- Ch.18 - Chemistry of the Environment105
- Ch.19 - Chemical Thermodynamics164
- Ch.20 - Electrochemistry171
- Ch.21 - Nuclear Chemistry122
- Ch.22 - Chemistry of the Nonmetals82
- Ch.23 - Transition Metals and Coordination Chemistry79
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry16
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 15, Problem 9
The reaction PCl₃(g) + Cl₂(g) ⇌ PCl₅(g) has Kp = 0.0870 at 300 _x001F_C. A flask is charged with 0.50 atm PCl₃, 0.50 atm Cl₂, and 0.20 atm PCl₅ at this temperature. (d) The reaction is exothermic. What effect will increasing the temperature of the system have on the mole fraction of Cl₂ in the equilibrium mixture?
Verified step by step guidance1
Identify that the reaction is exothermic, meaning heat is released as a product. According to Le Chatelier's principle, increasing the temperature will shift the equilibrium to favor the endothermic direction, which is the reverse reaction in this case.
Recognize that shifting the equilibrium towards the reactants (PCl₃ and Cl₂) will increase their concentrations at equilibrium.
Understand that the mole fraction of a component in a mixture is the ratio of its partial pressure to the total pressure of the system. Therefore, an increase in the partial pressure of Cl₂ will increase its mole fraction.
Consider the initial conditions: 0.50 atm PCl₃, 0.50 atm Cl₂, and 0.20 atm PCl₅. As the equilibrium shifts towards the reactants, the partial pressure of Cl₂ will increase, affecting its mole fraction.
Conclude that increasing the temperature will increase the mole fraction of Cl₂ in the equilibrium mixture, as the equilibrium shifts towards the reactants.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Le Chatelier's Principle
Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust itself to counteract the change and restore a new equilibrium. In the context of temperature changes, if the reaction is exothermic, increasing the temperature shifts the equilibrium position to favor the endothermic direction, which in this case would be the formation of reactants.
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07:32
Le Chatelier's Principle
Equilibrium Constant (Kp)
The equilibrium constant (Kp) for a reaction at a given temperature quantifies the ratio of the partial pressures of products to reactants at equilibrium. For the reaction PCl₃(g) + Cl₂(g) ⇌ PCl₅(g), Kp = 0.0870 indicates that at equilibrium, the concentration of PCl₅ is relatively low compared to the reactants. Changes in temperature can alter the value of Kp, affecting the equilibrium position.
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03:20Equilibrium Constant Expressions
Mole Fraction
Mole fraction is a way of expressing the concentration of a component in a mixture, defined as the number of moles of that component divided by the total number of moles of all components. In this reaction, the mole fraction of Cl₂ will change as the equilibrium shifts in response to temperature changes, impacting the overall composition of the gas mixture in the flask.
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00:36Mole Fraction Formula
Related Practice
Textbook Question
When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO2(𝑠)⇌2PbO(𝑠)+O2(𝑔). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true?
b. There will be less PbO2 remaining in vessel B,
Textbook Question
The diagram shown here represents the equilibrium state for the reaction A2(𝑔) + 2B(𝑔) ⇌ 2AB(𝑔). (a) Assuming the volume is 2 L, calculate the equilibrium constant 𝐾𝑐 for the reaction.
Textbook Question
The reaction A2 + B2 ⇌ 2 AB has an equilibrium constant Kc = 1.5. The following diagrams represent reaction mixtures containing A2 molecules (red), B2 molecules (blue), and AB molecules. (a) Which reaction mixture is at equilibrium?
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Textbook Question
When lead(IV) oxide is heated above 300°C, it decomposes according to the reaction, 2 PbO2(𝑠) ⇌ 2PbO(𝑠) + O2(𝑔). Consider the two sealed vessels of PbO2 shown here. If both vessels are heated to 400°C and allowed to come to equilibrium, which of the following statements is or are true? (c) The amount of PbO2 remaining in each vessel will be the same. [Find more in Section 15.4]
Textbook Question
Suppose that the gas-phase reactions A → B and B → A are both elementary reactions with rate constants of 4.7×10−3 s−1 and 5.8×10−1 s−1, respectively. (a) What is the value of the equilibrium constant for the equilibrium A(g) ⇌ B(g)? (b) Which is greater at equilibrium, the partial pressure of A or the partial pressure of B?