7: Energy and Chemical Processes
- Page ID
- 15926
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Energy is a vital component of the world around us. Nearly every physical and chemical process, including all the chemical reactions discussed in previous chapters, occurs with a simultaneous energy change. In this chapter, we will explore the nature of energy and how energy and chemistry are related.
- 7.0: Prelude to Energy and Chemical Processes
- This page discusses metabolism as a series of chemical reactions in cells that generate energy for essential functions, including temperature regulation in endotherms. It highlights the significance of metabolic issues, such as fever-related temperature changes in humans. Endotherms may hibernate to conserve energy when food is scarce. In contrast, ectotherms depend on external heat sources for temperature control.
- 7.1: Energy and Its Units
- This page defines energy as the ability to do work and relates it to heat and calories in nutrition and exercise. It explains energy transfer between objects with different temperatures and identifies joules as the standard unit for energy, work, and heat, alongside the use of calories in nutrition. Examples of food energy content are given, emphasizing the importance of energy balance through diet and exercise for health, along with a discussion on energy expenditures for physical activities.
- 7.2: Heat and Temperature
- This page explains the concept of temperature, its distinction from heat, and the key temperature scales: Fahrenheit, Celsius, and Kelvin. It discusses the relationship between heat transfer and temperature change, introducing specific heat capacity and providing examples of calculations for various materials. Body temperature, including normal ranges and conditions like fever and hypothermia, is highlighted, along with measurement methods.
- 7.3: Phase Changes
- This page discusses the states of matter (solid, liquid, gas) and the energy involved in phase changes, defined by heat addition (endothermic) or removal (exothermic). It covers melting and boiling points, heats of fusion and vaporization, and provides examples for calculating heat requirements. Sublimation is introduced, exemplified by dry ice, and related phenomena like freezer burn in stored foods.
- 7.4: Bond Energies and Chemical Reactions
- This page explains bond energy, enthalpy changes, and the classification of chemical reactions as exothermic or endothermic. It illustrates atoms forming compounds as a movement towards lower energy states. The text discusses the energy needed to break bonds, examples of reactions (like hydrogen and oxygen) for ΔH calculations, and visual representations of energy diagrams.
- 7.5: The Energy of Biochemical Reactions
- This page explains how energy changes are linked to chemical reactions in the body, focusing on glucose oxidation as a primary energy source. It details the energy provided by carbohydrates (4 kcal/g) and fats (9 kcal/g) and notes that ATP conversion releases about 7.5 kcal/mol to fuel cellular processes. Additionally, it highlights the role of dietitians in offering nutritional guidance to enhance health and manage dietary concerns.
- 7.E: Energy and Chemical Processes (Exercises)
- This page covers the classification of chemical reactions into exothermic and endothermic categories, including examples and energy change details. It addresses biochemical reactions, macronutrient caloric content, and adult male caloric requirements. Additionally, it features exercises on energy calculations, metabolism, specific heat, and temperature change energy requirements, along with provided answers to these exercises.
- 7.S: Energy and Chemical Processes (Summary)
- This page discusses energy and heat concepts, including their measurement in joules and calories. It covers heat transfer and phase changes occurring at constant temperature (isothermal), introducing specific heat, heat of fusion, and heat of vaporization. Energy changes in chemical reactions are linked to bond energies, distinguishing between exothermic reactions that release energy and endothermic reactions that absorb it.