Chapter 9: Thermochem
- Page ID
- 17221
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- Chapter 9.0: Introduction
- This page covers thermochemistry, focusing on energy changes in chemical reactions. It emphasizes that understanding a reaction involves considering the energy. The importance of energy in biological processes and industrial applications is highlighted. Readers will learn about practical thermochemical concepts, including cooling effects, caloric content, and the environmental impacts of energy consumption.
- Chapter 9.1 Energy Changes in Chemical Reactions
- This page covers the concept of energy, defining it as the capacity to do work and discussing its various forms, including kinetic and potential energy. It highlights the relationship between energy, work, and heat, and the law of conservation of energy. Additionally, it addresses energy transfer, calculations involving kinetic and potential energy, and thermochemistry, illustrating energy changes during chemical reactions.
- Chapter 9.2: Enthalpy and Reactions
- This page covers thermodynamics in chemistry, focusing on systems (open, closed, isolated), state functions, and energy transfer. It highlights work, internal energy, and enthalpy, establishing relationships between changes in enthalpy (ΔH) and internal energy (ΔE) during reactions. The extensive nature of enthalpy is explored through specific examples, including reactions and environmental contexts.
- Chapter 9.3: Hess's Law
- This page covers Hess's law, which asserts that the total enthalpy change for a reaction equals the sum of changes for individual steps, regardless of the pathway. It illustrates this with examples, including the thermite reaction and the combustion of carbon monoxide to carbon dioxide, providing detailed calculations.
- Chapter 9.4: Heats of Formation
- This page covers the concept of enthalpies of formation (ΔHf) and their significance in calculating reaction enthalpies (ΔHrxn) using Hess’s law. It defines ΔHf as the heat change for forming one mole of a compound from its elements under standard conditions.
- Chapter 9.5: Enthalpies of Solution
- This page discusses the enthalpy of solution (ΔHsoln), which describes the heat exchange during solute dissolution in a solvent, highlighting both exothermic and endothermic processes, such as with calcium chloride and ammonium nitrate. It also presents data on ΔHosoln for various compounds in water, classifying KOH and NaC2H3O2 as exothermic, while LiNO3 and KMnO4 are endothermic.
- Chapter 9.6: Calorimetry
- This page reviews calorimetry, the method for measuring enthalpy changes in chemical and physical processes through calorimeters. It covers principles of heat capacity and specific heat, explaining how they relate to temperature changes and heat flow during reactions.
- Chapter 9.7: Thermochem and Nutrition
- This page covers the intersection of thermochemistry and nutrition, detailing how food's caloric values relate to enthalpy of combustion and the conversion of nitrogen to urea. It explains the energy yield of different macronutrients and the importance of essential amino acids. Calculations of biochemical processes show reduced energy release for incomplete oxidation.
- Chapter 9.8: Energy Sources and the Environment
- This page emphasizes the critical role of fossil fuels in energy consumption, accounting for over 80% globally, while addressing environmental challenges prompting a shift to renewable sources due to climate change. It covers fossil fuel formation, energy potential of different fuels, and the economics of refining processes.
- Chapter 9.9: Essential Skills 4
- This page discusses temperature measurement, including unit conversions between Celsius and Kelvin, as well as dimensional analysis's role in ensuring accurate calculations, especially in energy. It highlights the difference between temperature and heat, offers conversion formulas, and provides examples. Practice problems are included to reinforce understanding of these concepts.
- Chapter 9.10: End of Chapter Material
- This page covers chemistry-related application problems, including energy yields in biochemical processes, combustion reactions, and metal smelting. It includes calculations for energy requirements and contrasts processes like fermentation and photosynthesis, addressing their historical implications.