Skip to main content
Pearson+ LogoPearson+ Logo
Ch.15 - Chemical Equilibrium
All textbooksMcMurry 8th EditionCh.15 - Chemical EquilibriumProblem 131
Chapter 15, Problem 131

Baking soda (sodium bicarbonate) decomposes when it is heated: 2 NaHCO31s2 ∆ Na2CO31s2 + CO21g2 + H2O1g2 ΔH° = + 136 kJ Consider an equilibrium mixture of reactants and products in a closed container. How does the number of moles of CO2 change when the mixture is disturbed by the following: (b) Adding water vapor

Verified step by step guidance
1
Identify the reaction: The decomposition of sodium bicarbonate is an endothermic reaction, as indicated by the positive ΔH° value (+136 kJ).
Understand the effect of adding water vapor: According to Le Chatelier's Principle, if a system at equilibrium is disturbed, it will adjust to minimize the disturbance.
Analyze the equilibrium shift: Adding water vapor increases the concentration of one of the products, H2O(g).
Predict the direction of the shift: The system will shift towards the reactants to counteract the increase in water vapor, thereby reducing the number of moles of CO2.
Conclude the effect on CO2: As the equilibrium shifts towards the reactants, the number of moles of CO2 will decrease.

Verified Solution

Video duration:
1m
This video solution was recommended by our tutors as helpful for the problem above.
Was this helpful?

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 that change and restore a new equilibrium. This principle is crucial for predicting how the addition of substances, such as water vapor, will affect the concentrations of reactants and products in a chemical reaction.
Recommended video:
Guided course
07:32
Le Chatelier's Principle

Equilibrium Constant (K)

The equilibrium constant (K) is a numerical value that expresses the ratio of the concentrations of products to reactants at equilibrium for a given reaction at a specific temperature. Changes in concentration, pressure, or temperature can shift the position of equilibrium, affecting the amounts of CO2 and other species present in the system.
Recommended video:
Guided course
01:14
Equilibrium Constant K

Effect of Water Vapor on Gas Equilibrium

In the context of gas equilibria, adding water vapor increases the total pressure of the system. According to Dalton's Law of Partial Pressures, this can shift the equilibrium position depending on the number of moles of gaseous products and reactants. In this case, the addition of water vapor may favor the production of CO2 if it leads to a decrease in the overall pressure of the gaseous components.
Recommended video:
Guided course
02:40
Raoult's Law and Vapor Pressure
Related Practice
Textbook Question
The following reaction is important in gold mining: 4 Au1s2 + 8 CN-1aq2 + O21g2 + 2 H2O1l2 ∆ 4 Au1CN22-1aq2 + 4 OH-1aq2For a reaction mixture at equilibrium, in which direction would the reaction go to reestablish equilibrium after each of the following changes? (a) Adding gold
294
views
Open Question
For the following reaction catalyzed by iridium, which is endothermic at 700 K: CaO(s) + CH₄(g) + 2 H₂O(g) ⇌ CaCO₃(s) + 4 H₂(g), how would the following changes affect the total quantity of CaCO₃ in the reaction mixture once equilibrium is reestablished at 700 K? (a) Increasing the temperature (b) Adding calcium oxide (c) Removing methane (CH₄) (d) Adding iridium.
Textbook Question
The equilibrium constant Kp for the reaction PCl51g2 ∆ PCl31g2 + Cl21g2 is 3.81 * 102 at 600 K and 2.69 * 103 at 700 K. (b) How are the equilibrium amounts of reactants and products affected by (iii) addition of a catalyst?
470
views
Textbook Question
A platinum catalyst is used in automobile catalytic convert- ers to hasten the oxidation of carbon monoxide: 2 CO1g2 + O 1g2 ∆Pt 2 CO 1g2 ΔH° = - 566 kJ Suppose that you have a reaction vessel containing an equilibrium mixture of CO1g2, O21g2, and CO21g2. Under the following conditions, will the amount of CO increase, decrease, or remain the same? (e) The pressure is increased by adding O2 gas.
496
views
Open Question
Consider the following gas-phase reaction: 2 Ag + Bg ⇌ Cg + Dg. An equilibrium mixture of reactants and products is subjected to the following changes: (a) A decrease in volume (b) An increase in temperature (c) Addition of reactants (d) Addition of a catalyst (e) Addition of an inert gas. Which of these changes affect the composition of the equilibrium mixture but leave the value of the equilibrium constant Kc unchanged? Which of the changes affect the value of Kc? Which affect neither the composition of the equilibrium mixture nor Kc?
Textbook Question
For the reaction A2 + 2B ∆ 2 AB, the rate of the for- ward reaction is 18 M/s and the rate of the reverse reaction is 12 M/s. The reaction is not at equilibrium. Will the reaction pro- ceed in the forward or reverse direction to attain equilibrium?
788
views