Textbook Question
Consider the following equilibrium, for which Δ𝐻<0
2 SO2(𝑔) + O2(𝑔) ⇌ 2 SO3(𝑔)
(f) How will each of the following changes affect an equilibrium mixture of the three gases: SO3(𝑔) is removed from the system?
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Ch.15 - Chemical Equilibrium
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232
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Table of contents
- Ch.1 - Introduction: Matter, Energy, and Measurement140
- Ch.2 - Atoms, Molecules, and Ions192
- Ch.3 - Chemical Reactions and Reaction Stoichiometry172
- Ch.4 - Reactions in Aqueous Solution156
- Ch.5 - Thermochemistry151
- Ch.6 - Electronic Structure of Atoms137
- Ch.7 - Periodic Properties of the Elements127
- Ch.8 - Basic Concepts of Chemical Bonding143
- Ch.9 - Molecular Geometry and Bonding Theories167
- Ch.10 - Gases147
- Ch.11 - Liquids and Intermolecular Forces97
- Ch.12 - Solids and Modern Materials129
- Ch.13 - Properties of Solutions126
- Ch.14 - Chemical Kinetics175
- Ch.15 - Chemical Equilibrium107
- Ch.16 - Acid-Base Equilibria127
- Ch.17 - Additional Aspects of Aqueous Equilibria133
- Ch.18 - Chemistry of the Environment88
- Ch.19 - Chemical Thermodynamics140
- Ch.20 - Electrochemistry137
- Ch.21 - Nuclear Chemistry99
- Ch.22 - Chemistry of the Nonmetals66
- Ch.23 - Transition Metals and Coordination Chemistry69
- Ch.24 - The Chemistry of Life: Organic and Biological Chemistry11
Brown14th EditionChemistry: The Central ScienceISBN: 9780134414232Not the one you use?Change textbook
Chapter 15, Problem 59
Methane, CH4, reacts with I2 according to the reaction CH4(g) + I2(g) ⇌ CH3I(g) + HI(g). At 630 K, Kp for this reaction is 2.26 × 10^-4. A reaction was set up at 630 K with initial partial pressures of methane at 105.1 torr and I2 at 7.96 torr. Calculate the pressures, in torr, of all reactants and products at equilibrium.
Verified step by step guidance1
Step 1: Write the expression for the equilibrium constant Kp for the reaction. For the reaction CH4(g) + I2(g) ⇌ CH3I(g) + HI(g), the expression is Kp = (P_CH3I * P_HI) / (P_CH4 * P_I2).
Step 2: Define the change in pressure for each species in terms of a variable, x. Assume that x is the change in pressure for CH4 and I2 as they react to form CH3I and HI. Therefore, the changes are: CH4: 105.1 - x, I2: 7.96 - x, CH3I: x, HI: x.
Step 3: Substitute the equilibrium pressures in terms of x into the Kp expression. This gives Kp = (x * x) / ((105.1 - x) * (7.96 - x)).
Step 4: Set the Kp expression equal to the given Kp value, 2.26 × 10^-4, and solve the resulting quadratic equation for x. This will involve expanding the equation and using the quadratic formula.
Step 5: Calculate the equilibrium pressures of all species using the value of x obtained from the quadratic equation. The pressures will be: P_CH4 = 105.1 - x, P_I2 = 7.96 - x, P_CH3I = x, P_HI = x.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Equilibrium Constant (Kp)
The equilibrium constant, Kp, is a numerical value that expresses the ratio of the partial pressures of the products to the partial pressures of the reactants at equilibrium for a given reaction at a specific temperature. For the reaction CH4(g) + I2(g) ⇌ CH3I(g) + HI(g), Kp is calculated using the formula Kp = (P_CH3I * P_HI) / (P_CH4 * P_I2). A small Kp value indicates that at equilibrium, the reaction favors the reactants over the products.
Recommended video:
Guided course
03:20
Equilibrium Constant Expressions
Partial Pressure
Partial pressure is the pressure exerted by a single component of a gas mixture. In the context of the reaction, the initial partial pressures of methane and iodine are given, and these values will change as the reaction progresses towards equilibrium. The total pressure of the system is the sum of the partial pressures of all gases present, and understanding how these pressures change is crucial for calculating equilibrium concentrations.
Recommended video:
Guided course
00:48Partial Pressure Calculation
ICE Table (Initial, Change, Equilibrium)
An ICE table is a tool used to organize the initial concentrations (or pressures), the changes that occur as the reaction proceeds, and the equilibrium concentrations (or pressures) of the reactants and products. By setting up an ICE table for the given reaction, one can systematically determine how the initial pressures of CH4 and I2 change as the system reaches equilibrium, allowing for the calculation of the equilibrium pressures of all species involved.
Recommended video:
Guided course
01:14ICE Charts and Equilibrium Amount
Related Practice
Textbook Question
At 80°C, 𝐾𝑐 = 1.87×10−3 for the reaction PH3BCl3(𝑠) ⇌ PH3(𝑔) + BCl3(𝑔) (a) Calculate the equilibrium concentrations of PH3 and BCl3 if a solid sample of PH3BCl3 is placed in a closed vessel at 80°C and decomposes until equilibrium is reached.
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Textbook Question
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (d) decrease the volume of the container in which the reaction occurs
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Textbook Question
Consider the reaction 4 NH3(𝑔) + 5 O2(𝑔) ⇌ 4 NO(𝑔) + 6 H2O(𝑔), Δ𝐻 = −904.4 kJ Does each of the following increase, decrease, or leave unchanged the yield of NO at equilibrium? (a) increase [NH3] (b) increase [H2O] (c) decrease [O2]
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Textbook Question
At 80°C, 𝐾𝑐 = 1.87×10−3 for the reaction PH3BCl3(𝑠) ⇌ PH3(𝑔) + BCl3(𝑔) (a) Calculate the equilibrium concentrations of PH3 and BCl3 if a solid sample of PH3BCl3 is placed in a closed vessel at 80°C and decomposes until equilibrium is reached. (b) If the flask has a volume of 0.250 L, what is the minimum mass of PH3BCl3(𝑠) that must be added to the flask to achieve equilibrium?
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