Textbook Question
(c) By what means can the internal energy of a closed system increase?
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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 25b
Calculate ΔE and determine whether the process is endothermic or exothermic for the following cases: (b) A system releases 66.1 kJ of heat to its surroundings while the surroundings do 44.0 kJ of work on the system.
Verified step by step guidance1
Understand the concept of energy change (ΔE) in a system, which is given by the formula: ΔE = q + w, where q is the heat exchanged and w is the work done.
Identify the values given in the problem: the system releases 66.1 kJ of heat, so q = -66.1 kJ (negative because heat is released), and the surroundings do 44.0 kJ of work on the system, so w = 44.0 kJ (positive because work is done on the system).
Substitute the values into the formula: ΔE = q + w = (-66.1 kJ) + (44.0 kJ).
Calculate the value of ΔE using the substituted values. This will give you the total energy change of the system.
Determine whether the process is endothermic or exothermic: if ΔE is positive, the process is endothermic (energy is absorbed by the system); if ΔE is negative, the process is exothermic (energy is released by the system).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
First Law of Thermodynamics
The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed from one form to another. In a closed system, the change in internal energy (ΔE) is equal to the heat added to the system minus the work done by the system. This principle is fundamental for analyzing energy changes in thermodynamic processes.
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Endothermic and Exothermic Processes
Endothermic processes absorb heat from the surroundings, resulting in a positive ΔE, while exothermic processes release heat, leading to a negative ΔE. Understanding whether a process is endothermic or exothermic is crucial for predicting the direction of energy flow and the system's behavior in response to heat and work interactions.
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Work and Heat in Thermodynamics
In thermodynamics, work and heat are two ways energy can be transferred between a system and its surroundings. Work is done on or by the system, while heat refers to energy transfer due to temperature differences. The signs of heat and work are essential for calculating ΔE and determining the nature of the process (endothermic or exothermic).
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Related Practice
Textbook Question
A gas is confined to a cylinder fitted with a piston and an electrical heater, as shown here:
Suppose that current is supplied to the heater so that 100 J of energy is added. Consider two different situations. In case (1) the piston is allowed to move as the energy is added. In case (2) the piston is fixed so that it cannot move. (b) Identify the sign (positive, negative, or zero) of q and w in each case?
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Textbook Question
Consider a system consisting of two oppositely charged spheres hanging by strings and separated by a distance r1, as shown in the accompanying illustration. Suppose they are separated to a larger distance r2, by moving them apart. (a) What change, if any, has occurred in the potential energy of the system?
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Textbook Question
Calculate ΔE and determine whether the process is endothermic or exothermic for the following cases: (a) q = 0.763 kJ and w = -840 J.
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Textbook Question
A gas is confined to a cylinder fitted with a piston and an electrical heater, as shown here:
Suppose that current is supplied to the heater so that 100 J of energy is added. Consider two different situations. In case (1) the piston is allowed to move as the energy is added. In case (2) the piston is fixed so that it cannot move. (a) In which case does the gas have the higher temperature after addition of the electrical energy?
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