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Ch.16 - Chemical Equilibrium
Chapter 16, Problem 81

Consider the reaction: H2(g) + I2(g) ⇌ 2 HI(g) A reaction mixture at equilibrium at 175 K contains PH2 = 0.958 atm, PI2 = 0.877 atm, and PHI = 0.020 atm. A second reaction mixture, also at 175 K, contains PH2 = PI2 = 0.621 atm and PHI = 0.101 atm. Is the second reaction at equilibrium? If not, what will be the partial pressure of HI when the reaction reaches equilibrium at 175 K?

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Chemical Equilibrium

Chemical equilibrium occurs when the rates of the forward and reverse reactions are equal, resulting in constant concentrations of reactants and products. In this state, the system appears static, but molecular activity continues. The equilibrium constant (K) quantifies the ratio of product concentrations to reactant concentrations at equilibrium, providing insight into the position of equilibrium.
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Le Chatelier's Principle

Le Chatelier's Principle states that if a dynamic equilibrium is disturbed by changing the conditions, the system will adjust to counteract the change and restore a new equilibrium. This principle helps predict how changes in concentration, pressure, or temperature will affect the position of equilibrium in a chemical reaction.
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Partial Pressure and the Ideal Gas Law

Partial pressure refers to the pressure exerted by an individual gas in a mixture, which can be calculated using Dalton's Law of Partial Pressures. The Ideal Gas Law (PV=nRT) relates the pressure, volume, and temperature of a gas, allowing for the determination of the behavior of gases under various conditions. Understanding these concepts is crucial for calculating equilibrium concentrations in gas-phase reactions.
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Related Practice
Textbook Question

At 650 K, the reaction MgCO3(s) ⇌ MgO(s) + CO2(g) has Kp = 0.026. A 10.0-L container at 650 K has 1.0 g of MgO(s) and CO2 at P = 0.0260 atm. The container is then compressed to a volume of 0.100 L. Find the mass of MgCO3 that is formed.

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Textbook Question

Consider the exothermic reaction: C2H4(g) + Cl2(g) ⇌ C2H4Cl2(g) If you were trying to maximize the amount of C2H4Cl2 produced, which tactic might you try? Assume that the reaction mixture reaches equilibrium. a. increasing the reaction volume b. removing C2H4Cl2 from the reaction mixture as it forms c. lowering the reaction temperature d. adding Cl2

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Textbook Question

Consider the endothermic reaction: C2H4(g) + I2(g) ⇌ C2H4I2(g) If you were trying to maximize the amount of C2H4I2 produced, which tactic might you try? Assume that the reaction mixture reaches equilibrium. a. decreasing the reaction volume b. removing I2 from the reaction mixture c. raising the reaction temperature d. adding C2H4 to the reaction mixture

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Textbook Question

A reaction vessel at 27 °C contains a mixture of SO2 (P = 3.00 atm) and O2 (P = 1.00 atm). When a catalyst is added, this reaction takes place: 2 SO2( g) + O2( g) ⇌ 2 SO3( g). At equilibrium, the total pressure is 3.75 atm. Find the value of Kc.

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Textbook Question

At 70 K, CCl4 decomposes to carbon and chlorine. The Kp for the decomposition is 0.76. Find the starting pressure of CCl4 at this temperature that will produce a total pressure of 1.0 atm at equilibrium.

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Textbook Question

The equilibrium constant for the reaction SO2(g) + NO2(g) ⇌ SO3(g) + NO(g) is Kc = 3.0. Find the amount of NO2 that must be added to 2.4 mol of SO2 in order to form 1.2 mol of SO3 at equilibrium.

2170
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