Textbook Question
What is ΔH for the explosion of nitroglycerin? (LO 9.14)2 C3H5(NO3)3(l) → 3 N2(g) + 1/2 O2(g) + 6 CO2(g) + 5 H2O(g)
Ch.9 - Thermochemistry: Chemical Energy
McMurry8th EditionChemistryISBN: 9781292336145
Not the one you use?Change textbookSelect a different textbook
Table of contents
- Ch.1 - Chemical Tools: Experimentation & Measurement170
- Ch.2 - Atoms, Molecules & Ions160
- Ch.3 - Mass Relationships in Chemical Reactions169
- Ch.4 - Reactions in Aqueous Solution199
- Ch.5 - Periodicity & Electronic Structure of Atoms102
- Ch.6 - Ionic Compounds: Periodic Trends and Bonding Theory92
- Ch.7 - Covalent Bonding and Electron-Dot Structures61
- Ch.8 - Covalent Compounds: Bonding Theories and Molecular Structure59
- Ch.9 - Thermochemistry: Chemical Energy122
- Ch.10 - Gases: Their Properties & Behavior155
- Ch.11 - Liquids & Phase Changes54
- Ch.12 - Solids and Solid-State Materials73
- Ch.13 - Solutions & Their Properties120
- Ch.14 - Chemical Kinetics98
- Ch.15 - Chemical Equilibrium125
- Ch.16 - Aqueous Equilibria: Acids & Bases110
- Ch.17 - Applications of Aqueous Equilibria147
- Ch.18 - Thermodynamics: Entropy, Free Energy & Equilibrium86
- Ch.19 - Electrochemistry154
- Ch.20 - Nuclear Chemistry96
- Ch.21 - Transition Elements and Coordination Chemistry156
- Ch.22 - The Main Group Elements187
- Ch.23 - Organic and Biological Chemistry51
Chapter 9, Problem 34
A piece of dry ice (solid CO2) is placed inside a balloon, and the balloon is tied shut. Over time, the carbon dioxide sub- limes, causing the balloon to increase in volume. Give the sign of the enthalpy change and the sign of work for the sublima-tion of CO2.
Verified step by step guidance1
Identify the process: Sublimation of CO2 involves the transition of solid carbon dioxide to its gaseous form within the sealed balloon.
Analyze the enthalpy change (\(\Delta H\)): Sublimation is an endothermic process, meaning it absorbs heat from the surroundings. Therefore, the sign of the enthalpy change (\(\Delta H\)) for the sublimation of CO2 is positive.
Consider the system and surroundings: The system is the CO2 and the balloon, while everything outside the balloon is the surroundings.
Determine the sign of work (w): As the CO2 sublimes and turns into gas, it expands against the balloon's elastic constraints, which means the system (CO2) is doing work on the surroundings (balloon). Work done by the system is considered negative.
Combine the concepts: The positive \(\Delta H\) indicates heat absorption, and the negative work (w) indicates that the system is expanding and doing work on its surroundings.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
2mWas this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Sublimation
Sublimation is the phase transition in which a substance changes directly from a solid to a gas without passing through the liquid phase. In the case of dry ice (solid CO2), it absorbs heat from its surroundings to overcome intermolecular forces, leading to an increase in volume as it transforms into gaseous CO2.
Recommended video:
Guided course
01:52
Sublimation Phase Change Example
Enthalpy Change (ΔH)
Enthalpy change (ΔH) refers to the heat content of a system at constant pressure. For sublimation, the process is endothermic, meaning it requires energy input, resulting in a positive enthalpy change. This indicates that heat is absorbed from the surroundings during the transition from solid to gas.
Recommended video:
Guided course
02:34Enthalpy of Formation
Work Done by the System
In thermodynamics, work done by the system is related to volume changes against external pressure. As the dry ice sublimates and the gas expands, the balloon's volume increases, doing work on the surroundings. This results in a positive sign for work, indicating that energy is transferred out of the system as the gas expands.
Recommended video:
Guided course
02:06Entropy of the System