Domanda del libro di testo
The change in internal energy for the combustion of 1.0 mol of octane at a pressure of 1.0 atm is 5084.3 kJ. If the change in enthalpy is 5074.1 kJ, how much work is done during the combustion?
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Ch.7 - Thermochemistry
Tro6th EditionChemistry: A Molecular ApproachISBN: 9780137832217
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TOC.tableOfContents
- Ch.1 - Matter, Measurement & Problem Solving118
- Ch.2 - Atoms & Elements106
- Ch.3 - Molecules and Compounds131
- Ch.4 - Chemical Reactions and Chemical Quantities56
- Ch.5 - Introduction to Solutions and Aqueous Solutions82
- Ch.6 - Gases114
- Ch.7 - Thermochemistry96
- Ch.8 - The Quantum-Mechanical Model of the Atom60
- Ch.9 - Periodic Properties of the Elements90
- Ch.10 - Chemical Bonding I: The Lewis Model89
- Ch.11 - Chemical Bonding II: Molecular Shapes, VSEPR & MO Theory85
- Ch.12 - Liquids, Solids & Intermolecular Forces51
- Ch.13 - Solids & Modern Materials47
- Ch.14 - Solutions90
- Ch.15 - Chemical Kinetics115
- Ch.16 - Chemical Equilibrium68
- Ch.17 - Acids and Bases136
- Ch.18 - Aqueous Ionic Equilibrium153
- Ch.19 - Free Energy & Thermodynamics93
- Ch.20 - Electrochemistry106
- Ch.21 - Radioactivity & Nuclear Chemistry74
- Ch.22 - Organic Chemistry140
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Capitolo 7, Problema 57
The air within a piston equipped with a cylinder absorbs 565 J of heat and expands from an initial volume of 0.10 L to a final volume of 0.85 L against an external pressure of 1.0 atm. What is the change in internal energy of the air within the piston?
Guida verificata passo dopo passo1
Identify the given values: heat absorbed (q) = 565 J, initial volume (V_i) = 0.10 L, final volume (V_f) = 0.85 L, and external pressure (P) = 1.0 atm.
Recall the first law of thermodynamics: \( \Delta U = q - w \), where \( \Delta U \) is the change in internal energy, \( q \) is the heat absorbed, and \( w \) is the work done by the system.
Calculate the work done by the system using the formula \( w = P \Delta V \), where \( \Delta V = V_f - V_i \). Convert the pressure from atm to J by using the conversion factor: 1 L·atm = 101.3 J.
Substitute the values into the work formula: \( w = 1.0 \text{ atm} \times (0.85 \text{ L} - 0.10 \text{ L}) \times 101.3 \text{ J/L·atm} \).
Substitute the values of \( q \) and \( w \) into the first law of thermodynamics equation to find \( \Delta U \): \( \Delta U = 565 \text{ J} - w \).
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Concetti chiave
Ecco i concetti essenziali che devi comprendere per rispondere correttamente alla domanda.
First Law of Thermodynamics
The First Law of Thermodynamics states that energy cannot be created or destroyed, only transformed. In a closed system, the change in internal energy (ΔU) is equal to the heat added to the system (Q) minus the work done by the system (W). This principle is essential for analyzing energy changes in thermodynamic processes.
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Percorso guidato
01:18
First Law of Thermodynamics
Work Done by a Gas
In thermodynamics, work done by a gas during expansion is calculated as W = PΔV, where P is the external pressure and ΔV is the change in volume. When a gas expands against an external pressure, it does work on the surroundings, which must be accounted for when determining the change in internal energy.
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01:52Work Function Calculation Example
Units of Energy
Energy in thermodynamics is often measured in joules (J) or liters-atmospheres (L·atm). When calculating work done by a gas, it is important to ensure that units are consistent. For example, converting L·atm to joules (1 L·atm = 101.3 J) may be necessary to accurately compute the change in internal energy.
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02:13SI Units
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