Textbook Question
During a deep breath, our lungs expand about 2.0 L againstan external pressure of 101.3 kPa. How much work is involvedin this process (in J)?
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Ch.5 - Thermochemistry
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 5, Problem 33
(c) For a given process at constant pressure, _x001F_H is negative. Is the process endothermic or exothermic?
Verified step by step guidance1
Step 1: Understand the terms 'endothermic' and 'exothermic'. An endothermic process absorbs heat from the surroundings, while an exothermic process releases heat to the surroundings.
Step 2: Recognize that the symbol ΔH represents the change in enthalpy, which is the heat change at constant pressure.
Step 3: Note that a negative ΔH indicates that the system is losing heat to the surroundings.
Step 4: Connect the concept of a negative ΔH with the definition of an exothermic process, which is characterized by the release of heat.
Step 5: Conclude that if ΔH is negative, the process is exothermic, as it involves the release of heat to the surroundings.
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Enthalpy Change (_x001F_H)
Enthalpy change (_x001F_H) is a measure of the heat absorbed or released during a chemical reaction or physical process at constant pressure. A negative _x001F_H indicates that the system releases heat to the surroundings, which is a key characteristic of exothermic processes.
Exothermic vs. Endothermic Processes
Exothermic processes are those that release energy, usually in the form of heat, to the surroundings, resulting in a temperature increase in the environment. In contrast, endothermic processes absorb energy from the surroundings, leading to a temperature decrease. The sign of the enthalpy change helps determine the nature of the process.
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Guided course
01:23
Endothermic & Exothermic Reactions Example 2
Constant Pressure Conditions
Constant pressure conditions are often encountered in chemical reactions occurring in open systems, where the pressure remains stable throughout the process. Under these conditions, the enthalpy change is directly related to the heat exchanged, making it easier to classify the reaction as either exothermic or endothermic based on the sign of _x001F_H.
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02:35Constant-Pressure Calorimetry
Related Practice
Textbook Question
(a) What is meant by the term state function? (b) Give an example of a quantity that is a state function and one that is not. (c) Is the volume of a system a state function? Why or why not?
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Textbook Question
How much work (in J) is involved in a chemical reaction ifthe volume decreases from 33.6 L to 11.2 L against a constantpressure of 90.5 kPa?
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Textbook Question
A gas is confined to a cylinder under constant atmospheric pressure, as illustrated in Figure 5.4. When 0.49 kJ of heat is added to the gas, it expands and does 214 J of work on the surroundings. What are the values of H and E for this process?
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