This document contains 57 slides summarizing key concepts in thermochemistry from a general chemistry textbook. It introduces terminology like heat, work, kinetic energy, and potential energy. It discusses heat capacity, calorimetry, heats of reaction, and how the first law of thermodynamics relates energy changes to heat and work. Hess's law and standard enthalpies of formation are explained. Finally, it touches on fuels as energy sources and global warming related to carbon dioxide emissions.
This document is a slide presentation on chapter 5 from a general chemistry textbook. It covers the following topics:
- The nature of aqueous solutions, including strong/weak electrolytes and non-electrolytes.
- Precipitation reactions that form insoluble compounds. Net ionic equations are introduced.
- Acid-base reactions defined by Brønsted-Lowry theory. Examples of acid-base reactions are given.
- Oxidation-reduction reactions are introduced through examples. Half-reactions and balancing redox equations using the half-reaction method are covered.
- Oxidizing and reducing agents are defined based on whether the element is gaining or losing electrons in a
This document provides an overview of chemical bonding concepts including:
- Lewis theory which describes how atoms bond via electron transfers or sharing to achieve stable octet configurations.
- Covalent bonds are formed by shared electron pairs between atoms. Polar covalent bonds form when bonding electrons are shared unequally.
- Valence shell electron pair repulsion (VSEPR) theory is used to predict molecular geometry based on electron pair arrangements.
- Exceptions to the octet rule exist for species with incomplete or expanded octets.
- Bond order corresponds to bond strength and length, with single, double and triple bonds represented by bond orders of 1, 2, and 3 respectively.
This document is a slide presentation on chapter 1 of a general chemistry textbook. It covers the following key topics:
1) The scientific method and its application to chemistry.
2) The basic properties of matter including composition, physical and chemical properties, and the classification of elements, compounds, and molecules.
3) The measurement of various chemical properties including mass, temperature, volume, and density. It also discusses units of measurement and uncertainties in scientific measurements.
4) Significant figures and how they impact calculations and measurements.
This document is a presentation on chemical compounds from a general chemistry textbook. It discusses different types of chemical compounds such as molecular and ionic compounds. It explains how to determine the formula of a compound from its composition percentages and introduces oxidation states as a tool for describing compounds. The presentation also covers naming conventions for inorganic and organic compounds, including binary compounds, acids, and functional groups. Visual examples are provided to illustrate key compounds and concepts.
This document discusses chemical reactions and stoichiometry. It introduces chemical equations and how to balance them. It explains how stoichiometry is used to quantify relationships in chemical formulas, chemical equations, mole ratios and reaction yields. Limiting reagents and theoretical, actual and percent yields of products are also covered. Finally, it discusses consecutive, simultaneous and overall reactions as well as reaction intermediates.
This document is a 35 slide presentation on chapter 9 of a general chemistry textbook. It covers topics relating to the periodic table, including classifying elements based on the periodic law, atomic and ionic properties such as size and ionization energy, and periodic trends in properties like electronegativity and melting points. Many figures and diagrams are included to illustrate concepts like effective nuclear charge, atomic and ionic radii, and trends in first ionization energy down groups of the periodic table.
IB Chemistry on Hess's Law, Enthalpy Formation and CombustionLawrence kok
1) Hess's law states that the enthalpy change of a reaction is independent of the pathway and is equal to the sum of the enthalpy changes of the steps.
2) Standard enthalpy changes of formation (ΔHf°) can be used to calculate the enthalpy change (ΔH°) of a reaction by adding the standard enthalpies of formation of products and subtracting the standard enthalpies of formation of reactants.
3) For the reaction 2H2S + SO2 → 3S + 2H2O, the calculated standard enthalpy change is -234 kJ/mol.
This document is a slide presentation on chapter 5 from a general chemistry textbook. It covers the following topics:
- The nature of aqueous solutions, including strong/weak electrolytes and non-electrolytes.
- Precipitation reactions that form insoluble compounds. Net ionic equations are introduced.
- Acid-base reactions defined by Brønsted-Lowry theory. Examples of acid-base reactions are given.
- Oxidation-reduction reactions are introduced through examples. Half-reactions and balancing redox equations using the half-reaction method are covered.
- Oxidizing and reducing agents are defined based on whether the element is gaining or losing electrons in a
This document provides an overview of chemical bonding concepts including:
- Lewis theory which describes how atoms bond via electron transfers or sharing to achieve stable octet configurations.
- Covalent bonds are formed by shared electron pairs between atoms. Polar covalent bonds form when bonding electrons are shared unequally.
- Valence shell electron pair repulsion (VSEPR) theory is used to predict molecular geometry based on electron pair arrangements.
- Exceptions to the octet rule exist for species with incomplete or expanded octets.
- Bond order corresponds to bond strength and length, with single, double and triple bonds represented by bond orders of 1, 2, and 3 respectively.
This document is a slide presentation on chapter 1 of a general chemistry textbook. It covers the following key topics:
1) The scientific method and its application to chemistry.
2) The basic properties of matter including composition, physical and chemical properties, and the classification of elements, compounds, and molecules.
3) The measurement of various chemical properties including mass, temperature, volume, and density. It also discusses units of measurement and uncertainties in scientific measurements.
4) Significant figures and how they impact calculations and measurements.
This document is a presentation on chemical compounds from a general chemistry textbook. It discusses different types of chemical compounds such as molecular and ionic compounds. It explains how to determine the formula of a compound from its composition percentages and introduces oxidation states as a tool for describing compounds. The presentation also covers naming conventions for inorganic and organic compounds, including binary compounds, acids, and functional groups. Visual examples are provided to illustrate key compounds and concepts.
This document discusses chemical reactions and stoichiometry. It introduces chemical equations and how to balance them. It explains how stoichiometry is used to quantify relationships in chemical formulas, chemical equations, mole ratios and reaction yields. Limiting reagents and theoretical, actual and percent yields of products are also covered. Finally, it discusses consecutive, simultaneous and overall reactions as well as reaction intermediates.
This document is a 35 slide presentation on chapter 9 of a general chemistry textbook. It covers topics relating to the periodic table, including classifying elements based on the periodic law, atomic and ionic properties such as size and ionization energy, and periodic trends in properties like electronegativity and melting points. Many figures and diagrams are included to illustrate concepts like effective nuclear charge, atomic and ionic radii, and trends in first ionization energy down groups of the periodic table.
IB Chemistry on Hess's Law, Enthalpy Formation and CombustionLawrence kok
1) Hess's law states that the enthalpy change of a reaction is independent of the pathway and is equal to the sum of the enthalpy changes of the steps.
2) Standard enthalpy changes of formation (ΔHf°) can be used to calculate the enthalpy change (ΔH°) of a reaction by adding the standard enthalpies of formation of products and subtracting the standard enthalpies of formation of reactants.
3) For the reaction 2H2S + SO2 → 3S + 2H2O, the calculated standard enthalpy change is -234 kJ/mol.
This document is a chapter from a general chemistry textbook about atoms and the atomic theory. It discusses early discoveries in chemistry that led to modern atomic theory, including Dalton's atomic theory. It also describes experiments that showed atoms are made of a small, dense nucleus surrounded by electrons, including discovery of the electron, proton, and neutron. The chapter concludes by explaining isotopes, atomic numbers, mass numbers, and how the mole is used to relate mass to number of particles.
This chapter discusses thermochemistry and the concepts of heat, work, internal energy, enthalpy, and the first law of thermodynamics. It introduces terminology like system, surroundings, heat capacity, and heat of reaction. Methods for determining heats of reaction through calorimetry are presented, including bomb calorimetry and coffee cup calorimetry. The relationship between internal energy, enthalpy, and heat of reaction is explored. Standard states and standard enthalpy changes are defined. Hess's law for determining heats of reaction indirectly is introduced.
Chapter 18.1 : The Nature of Chemical EquilibriumChris Foltz
This document provides information about chemical equilibrium, including definitions, concepts, and examples. It defines chemical equilibrium as a state where the rates of the forward and reverse reactions are equal and the concentrations of reactants and products remain constant. The equilibrium constant, K, is introduced as a ratio of product concentrations over reactant concentrations raised to their stoichiometric coefficients. Examples are provided to demonstrate how to write equilibrium expressions and calculate K values or concentrations at equilibrium.
This document provides an overview of nuclear magnetic resonance (NMR) spectroscopy. It discusses key concepts such as nuclear spin, the splitting of energy levels in an external magnetic field, and how NMR spectra provide information about a molecule's structure. Specific topics covered include proton and carbon-13 NMR, chemical shifts, spin-spin splitting, coupling constants, and techniques for analyzing complex NMR spectra.
This chapter discusses the quantum mechanical model of the atom. It covers early theories of electromagnetic radiation and the photoelectric effect that led to the development of quantum theory. The chapter then describes the Bohr model of the atom and its limitations. It introduces wave mechanics and the Schrodinger equation for describing electron orbitals. The chapter covers electron configurations, orbital shapes, and how quantum numbers are used to interpret and represent atomic orbitals. It also discusses how electron configurations relate to the periodic table.
Ammonia is a colorless gas with a sharp, irritating odor. It exists as a gas at room temperature but can also be a liquid or solid depending on temperature and pressure. Ammonia has a molecular mass of 17.03 g/mol and is made up of one nitrogen atom bonded to three hydrogen atoms in a triangular pyramid shape. Ammonia is a weak base that readily dissolves in water and is highly reactive, acting as a strong reducing agent in chemical reactions. Common physical and chemical properties of ammonia are described.
This chapter discusses chemical reactions and their mechanisms. It introduces key concepts like reactants and products, reaction mechanisms, kinetics, thermodynamics, and types of reaction intermediates. Specifically, it examines the chlorination of methane as a free radical chain reaction, discussing the initiation, propagation, and termination steps. It also covers factors that determine reaction rates like activation energy, temperature, and stability of intermediates like carbocations, carbanions, free radicals, and carbenes.
This document summarizes Chapter 10 from the textbook "General Chemistry: Principles and Modern Applications". The chapter discusses the periodic table and atomic properties. It covers the periodic law, classification of elements as metals and nonmetals, sizes of atoms and ions, ionization energy, electron affinity, and periodic trends in properties like melting points. The chapter also examines magnetic properties and how the periodic table can be used to predict trends in chemical behavior.
This document contains 55 slides from a university chemistry lecture on intermolecular forces, liquids, solids, and crystal structures. The slides cover topics such as van der Waals forces, hydrogen bonding, properties of liquids and solids including vapor pressure, phase diagrams, and crystal structures including ionic solids and closest packing. Figures and diagrams are included to illustrate concepts such as dipole-dipole interactions, hydrogen bonding networks, unit cell structures, and X-ray diffraction.
This chapter discusses chemical kinetics and reaction rates. It introduces concepts such as the rate of a reaction, methods of measuring reaction rates, and how concentration and temperature affect reaction rates. Specific reaction orders including zero-order, first-order, and second-order reactions are covered. Integrated rate laws are presented for determining reactant concentrations over time. The chapter also discusses theoretical models for chemical kinetics, including collision theory and activation energy, and how the Arrhenius equation describes the temperature dependence of reaction rates.
This chapter of the general chemistry textbook discusses solubility and complex ion equilibria. It covers topics such as the solubility product constant Ksp, the common ion effect, limitations of Ksp, criteria for precipitation, fractional precipitation, effects of pH on solubility, and equilibria involving complex ions. It also describes the process of qualitative cation analysis using selective precipitation of cations in different solubility groups.
IB Chemistry on Titration Curves between Acids and BasesLawrence kok
1) Neutralization reactions involve the reaction between acids and bases to form water and a salt. The type of salt formed depends on whether a strong acid reacts with a strong base, strong acid with weak base, weak acid with strong base, or weak acid with weak base.
2) Titration curves show the change in pH during a neutralization reaction. For a strong acid with a strong base, the pH changes rapidly at the equivalence point of 7. For a strong acid with a weak base, the equivalence point pH is below 7 due to salt hydrolysis. For a weak acid with a strong base, the equivalence point pH is above 7. Weak acid with weak base shows a gradual pH change over
This document summarizes the synthesis and study of transition metal complexes of benzaldimino-1,3,4-thiadiazole-2-thiol (BTT). The author synthesized the ligand BTT and its copper, nickel, cobalt, and zinc complexes. The complexes were characterized using infrared spectroscopy, electronic spectroscopy, ESR, cyclic voltammetry, NMR, and magnetic susceptibility measurements. Spectroscopic data indicated the ligand behaves as a bidentate ligand, forming octahedral complexes with the metals. The author thanks advisors and colleagues and concludes the spectral studies support an octahedral geometry for the complexes.
This document provides an overview of key concepts related to the mole concept in chemistry. It defines the mole as the number of atoms or molecules in 1 gram of hydrogen or 12 grams of carbon. The mole concept allows chemists to relate mass, number of particles, and volume of gases. It discusses how to calculate empirical and molecular formulas, Avogadro's constant, molar mass, limiting reactants, and other mole-related calculations and applications. Worked examples are provided to demonstrate how to use the mole concept to find formulas of compounds from percentage composition data and other information.
This document is a chapter from a general chemistry textbook. It is chapter 6, which covers gases. The chapter contains 9 sections that discuss gas properties and laws, including gas pressure, the simple gas laws, the ideal gas equation, applications of the ideal gas equation like determining molar mass, gases in chemical reactions, mixtures of gases, kinetic molecular theory, gas properties related to kinetic molecular theory, and non-ideal gases. The chapter also includes sample problems and questions at the end.
This document provides an overview of Chapter 5 from a general chemistry textbook. Chapter 5 covers reactions in aqueous solutions, including precipitation reactions, acid-base reactions, and oxidation-reduction reactions. It defines key concepts like electrolytes, precipitation, acids and bases. It also explains how to balance redox reactions and identify oxidizing and reducing agents. The chapter focuses on stoichiometry and titration reactions in aqueous solutions.
The Lindemann-Hinshelwood mechanism explains how first-order unimolecular gas-phase reactions can occur through collisions. It proposes that: (1) A reactant molecule A becomes energized through a collision with another A molecule, forming the excited species A*. (2) A* then either loses its excess energy through another collision or undergoes unimolecular decay to form products P. (3) If the unimolecular decay is the slowest step, the overall reaction appears first-order. The mechanism predicts a transition to second-order kinetics at low pressures when bimolecular collisions become rate-determining.
This document outlines the key concepts and learning objectives for Chapter 17, which covers solubility equilibria and complex-ion equilibria. The chapter will examine how to determine solubility product constants (Ksp) and use them to calculate solubility. It will also explore how the common ion effect and pH can impact solubility. The chapter will then discuss the formation of complex ions and how they relate to solubility and precipitation. It concludes by looking at applications to qualitative metal ion analysis.
This document provides an overview of Chapter 25 from the textbook "Prentice-Hall General Chemistry" by Petrucci, Harwood, and Herring. The chapter discusses Werner's theory of coordination compounds, ligands, nomenclature, isomerism, bonding in complex ions using crystal field theory, magnetic properties, color, equilibria of complex ions, acid-base reactions, and applications of coordination chemistry. It includes tables, diagrams, examples and contents to explain these concepts in coordination chemistry.
This document provides an overview of Chapter 7 (Thermochemistry) from a general chemistry textbook. It covers key concepts like heat, work, the first law of thermodynamics, and enthalpy changes. The chapter discusses how to calculate heat capacities, heats of reaction using calorimetry, and pressure-volume work. It also defines state functions like internal energy and enthalpy, and distinguishes between heat, work, and changes in internal energy or enthalpy during chemical reactions. Standard enthalpy changes are introduced as well.
This document provides an overview of Chapter 6: Thermochemistry from a textbook. It includes the following:
- Section 6.1 covers the nature of energy, including defining energy, work, potential energy, kinetic energy, endothermic and exothermic processes. It discusses the first law of thermodynamics and enthalpy.
- Section 6.2 discusses enthalpy changes, calorimetry (measuring heat), and using calorimetry to solve problems involving heat and temperature changes.
- The document provides learning objectives, tables of contents, definitions, concepts, examples, and practice problems to help students understand thermochemistry concepts.
This document is a chapter from a general chemistry textbook about atoms and the atomic theory. It discusses early discoveries in chemistry that led to modern atomic theory, including Dalton's atomic theory. It also describes experiments that showed atoms are made of a small, dense nucleus surrounded by electrons, including discovery of the electron, proton, and neutron. The chapter concludes by explaining isotopes, atomic numbers, mass numbers, and how the mole is used to relate mass to number of particles.
This chapter discusses thermochemistry and the concepts of heat, work, internal energy, enthalpy, and the first law of thermodynamics. It introduces terminology like system, surroundings, heat capacity, and heat of reaction. Methods for determining heats of reaction through calorimetry are presented, including bomb calorimetry and coffee cup calorimetry. The relationship between internal energy, enthalpy, and heat of reaction is explored. Standard states and standard enthalpy changes are defined. Hess's law for determining heats of reaction indirectly is introduced.
Chapter 18.1 : The Nature of Chemical EquilibriumChris Foltz
This document provides information about chemical equilibrium, including definitions, concepts, and examples. It defines chemical equilibrium as a state where the rates of the forward and reverse reactions are equal and the concentrations of reactants and products remain constant. The equilibrium constant, K, is introduced as a ratio of product concentrations over reactant concentrations raised to their stoichiometric coefficients. Examples are provided to demonstrate how to write equilibrium expressions and calculate K values or concentrations at equilibrium.
This document provides an overview of nuclear magnetic resonance (NMR) spectroscopy. It discusses key concepts such as nuclear spin, the splitting of energy levels in an external magnetic field, and how NMR spectra provide information about a molecule's structure. Specific topics covered include proton and carbon-13 NMR, chemical shifts, spin-spin splitting, coupling constants, and techniques for analyzing complex NMR spectra.
This chapter discusses the quantum mechanical model of the atom. It covers early theories of electromagnetic radiation and the photoelectric effect that led to the development of quantum theory. The chapter then describes the Bohr model of the atom and its limitations. It introduces wave mechanics and the Schrodinger equation for describing electron orbitals. The chapter covers electron configurations, orbital shapes, and how quantum numbers are used to interpret and represent atomic orbitals. It also discusses how electron configurations relate to the periodic table.
Ammonia is a colorless gas with a sharp, irritating odor. It exists as a gas at room temperature but can also be a liquid or solid depending on temperature and pressure. Ammonia has a molecular mass of 17.03 g/mol and is made up of one nitrogen atom bonded to three hydrogen atoms in a triangular pyramid shape. Ammonia is a weak base that readily dissolves in water and is highly reactive, acting as a strong reducing agent in chemical reactions. Common physical and chemical properties of ammonia are described.
This chapter discusses chemical reactions and their mechanisms. It introduces key concepts like reactants and products, reaction mechanisms, kinetics, thermodynamics, and types of reaction intermediates. Specifically, it examines the chlorination of methane as a free radical chain reaction, discussing the initiation, propagation, and termination steps. It also covers factors that determine reaction rates like activation energy, temperature, and stability of intermediates like carbocations, carbanions, free radicals, and carbenes.
This document summarizes Chapter 10 from the textbook "General Chemistry: Principles and Modern Applications". The chapter discusses the periodic table and atomic properties. It covers the periodic law, classification of elements as metals and nonmetals, sizes of atoms and ions, ionization energy, electron affinity, and periodic trends in properties like melting points. The chapter also examines magnetic properties and how the periodic table can be used to predict trends in chemical behavior.
This document contains 55 slides from a university chemistry lecture on intermolecular forces, liquids, solids, and crystal structures. The slides cover topics such as van der Waals forces, hydrogen bonding, properties of liquids and solids including vapor pressure, phase diagrams, and crystal structures including ionic solids and closest packing. Figures and diagrams are included to illustrate concepts such as dipole-dipole interactions, hydrogen bonding networks, unit cell structures, and X-ray diffraction.
This chapter discusses chemical kinetics and reaction rates. It introduces concepts such as the rate of a reaction, methods of measuring reaction rates, and how concentration and temperature affect reaction rates. Specific reaction orders including zero-order, first-order, and second-order reactions are covered. Integrated rate laws are presented for determining reactant concentrations over time. The chapter also discusses theoretical models for chemical kinetics, including collision theory and activation energy, and how the Arrhenius equation describes the temperature dependence of reaction rates.
This chapter of the general chemistry textbook discusses solubility and complex ion equilibria. It covers topics such as the solubility product constant Ksp, the common ion effect, limitations of Ksp, criteria for precipitation, fractional precipitation, effects of pH on solubility, and equilibria involving complex ions. It also describes the process of qualitative cation analysis using selective precipitation of cations in different solubility groups.
IB Chemistry on Titration Curves between Acids and BasesLawrence kok
1) Neutralization reactions involve the reaction between acids and bases to form water and a salt. The type of salt formed depends on whether a strong acid reacts with a strong base, strong acid with weak base, weak acid with strong base, or weak acid with weak base.
2) Titration curves show the change in pH during a neutralization reaction. For a strong acid with a strong base, the pH changes rapidly at the equivalence point of 7. For a strong acid with a weak base, the equivalence point pH is below 7 due to salt hydrolysis. For a weak acid with a strong base, the equivalence point pH is above 7. Weak acid with weak base shows a gradual pH change over
This document summarizes the synthesis and study of transition metal complexes of benzaldimino-1,3,4-thiadiazole-2-thiol (BTT). The author synthesized the ligand BTT and its copper, nickel, cobalt, and zinc complexes. The complexes were characterized using infrared spectroscopy, electronic spectroscopy, ESR, cyclic voltammetry, NMR, and magnetic susceptibility measurements. Spectroscopic data indicated the ligand behaves as a bidentate ligand, forming octahedral complexes with the metals. The author thanks advisors and colleagues and concludes the spectral studies support an octahedral geometry for the complexes.
This document provides an overview of key concepts related to the mole concept in chemistry. It defines the mole as the number of atoms or molecules in 1 gram of hydrogen or 12 grams of carbon. The mole concept allows chemists to relate mass, number of particles, and volume of gases. It discusses how to calculate empirical and molecular formulas, Avogadro's constant, molar mass, limiting reactants, and other mole-related calculations and applications. Worked examples are provided to demonstrate how to use the mole concept to find formulas of compounds from percentage composition data and other information.
This document is a chapter from a general chemistry textbook. It is chapter 6, which covers gases. The chapter contains 9 sections that discuss gas properties and laws, including gas pressure, the simple gas laws, the ideal gas equation, applications of the ideal gas equation like determining molar mass, gases in chemical reactions, mixtures of gases, kinetic molecular theory, gas properties related to kinetic molecular theory, and non-ideal gases. The chapter also includes sample problems and questions at the end.
This document provides an overview of Chapter 5 from a general chemistry textbook. Chapter 5 covers reactions in aqueous solutions, including precipitation reactions, acid-base reactions, and oxidation-reduction reactions. It defines key concepts like electrolytes, precipitation, acids and bases. It also explains how to balance redox reactions and identify oxidizing and reducing agents. The chapter focuses on stoichiometry and titration reactions in aqueous solutions.
The Lindemann-Hinshelwood mechanism explains how first-order unimolecular gas-phase reactions can occur through collisions. It proposes that: (1) A reactant molecule A becomes energized through a collision with another A molecule, forming the excited species A*. (2) A* then either loses its excess energy through another collision or undergoes unimolecular decay to form products P. (3) If the unimolecular decay is the slowest step, the overall reaction appears first-order. The mechanism predicts a transition to second-order kinetics at low pressures when bimolecular collisions become rate-determining.
This document outlines the key concepts and learning objectives for Chapter 17, which covers solubility equilibria and complex-ion equilibria. The chapter will examine how to determine solubility product constants (Ksp) and use them to calculate solubility. It will also explore how the common ion effect and pH can impact solubility. The chapter will then discuss the formation of complex ions and how they relate to solubility and precipitation. It concludes by looking at applications to qualitative metal ion analysis.
This document provides an overview of Chapter 25 from the textbook "Prentice-Hall General Chemistry" by Petrucci, Harwood, and Herring. The chapter discusses Werner's theory of coordination compounds, ligands, nomenclature, isomerism, bonding in complex ions using crystal field theory, magnetic properties, color, equilibria of complex ions, acid-base reactions, and applications of coordination chemistry. It includes tables, diagrams, examples and contents to explain these concepts in coordination chemistry.
This document provides an overview of Chapter 7 (Thermochemistry) from a general chemistry textbook. It covers key concepts like heat, work, the first law of thermodynamics, and enthalpy changes. The chapter discusses how to calculate heat capacities, heats of reaction using calorimetry, and pressure-volume work. It also defines state functions like internal energy and enthalpy, and distinguishes between heat, work, and changes in internal energy or enthalpy during chemical reactions. Standard enthalpy changes are introduced as well.
This document provides an overview of Chapter 6: Thermochemistry from a textbook. It includes the following:
- Section 6.1 covers the nature of energy, including defining energy, work, potential energy, kinetic energy, endothermic and exothermic processes. It discusses the first law of thermodynamics and enthalpy.
- Section 6.2 discusses enthalpy changes, calorimetry (measuring heat), and using calorimetry to solve problems involving heat and temperature changes.
- The document provides learning objectives, tables of contents, definitions, concepts, examples, and practice problems to help students understand thermochemistry concepts.
This document provides an overview of thermochemistry and calorimetry. It discusses:
1) Thermochemistry deals with the heat involved in chemical and physical changes. Energy can be transferred between a system and its surroundings as heat or work.
2) Enthalpy (H) is a measure of the total energy of a system at constant pressure. For reactions that do not involve large volume changes, change in enthalpy (ΔH) can approximate change in energy (ΔE).
3) Calorimetry involves measuring heat transfer during chemical or physical changes using devices like coffee cup calorimeters. The heat transferred (q) can be calculated using specific heat capacity (c), mass (
The document provides an overview of key concepts in thermochemistry including:
- Defining energy, work, potential energy, kinetic energy, and endothermic and exothermic processes.
- The first law of thermodynamics and how changes in internal energy can be calculated using heat and work.
- How enthalpy changes can be determined using calorimetry and Hess's law.
- How standard enthalpies of formation are used to calculate enthalpy changes in chemical reactions.
The document covers fundamental thermochemistry concepts and calculations in chemistry.
This document discusses thermochemistry and calorimetry. It defines key concepts in thermochemistry including the various forms of energy, exothermic and endothermic processes, and systems and surroundings. It introduces the first law of thermodynamics and defines state functions. It also discusses enthalpy, thermochemical equations, and calculations involving enthalpy changes. The document explains calorimetry concepts like heat capacity, specific heat, and how to perform calculations using bomb and coffee cup calorimetry.
Thermochemistry is the study of heat changes in chemical reactions. Thermal energy is the energy associated with the random motion of atoms and molecules. Enthalpy (H) is a state function that represents the total energy of a system at constant pressure. The standard enthalpy of formation (ΔHf°) is the change in enthalpy that accompanies the formation of one mole of a compound from its elements in their standard states. Hess's law states that the enthalpy change for a reaction is equal to the sum of the enthalpy changes of the steps in any possible pathway between the initial and final states of the reaction.
New chm-151-unit-9-power-points-140227172226-phpapp01Cleophas Rwemera
Thermochemistry deals with heat and energy changes during chemical and physical processes. There are several key concepts:
1) Enthalpy (H) is a measure of the total energy of a system at constant pressure. For reactions that do not involve large volume changes, the enthalpy change (ΔH) can approximate the energy change (ΔE).
2) Calorimetry experiments allow measurement of heat changes (q) through determination of temperature changes of reaction mixtures using their specific heats.
3) Hess's law states that the enthalpy change for a reaction is the same whether the process occurs in one step or multiple steps. Standard enthalpy changes (ΔH°) can
This document contains the solutions to homework problems assigned in a thermodynamics course. It provides instructions for submitting homework solutions, including showing all work. It then lists 7 problems and provides the numerical solutions. The problems cover various thermodynamic concepts like the ideal gas law, polytropic processes, work calculations, property tables and definitions.
1. The document is a chapter-by-chapter summary of General Physical Chemistry by Dr. Fateh Eltaboni.
2. Chapter 2 discusses thermochemistry and thermodynamics, including heat transfer, exothermic and endothermic processes, state functions, the first law of thermodynamics, and enthalpy.
3. Key concepts covered are heat, temperature, thermochemistry, systems, state functions, the relationship between work and energy, and calorimetry.
This document provides an overview of key concepts in Chapter 13 on chemical equilibrium. It discusses how at the molecular level reactions are highly dynamic even when concentrations appear constant at the macroscopic level. Equilibrium is the state where the rates of the forward and reverse reactions are equal. The equilibrium constant, K, provides a quantitative measure of the position of equilibrium. K depends on temperature but not the amounts of reactants and products initially present. Problems involving equilibrium can be solved using an ICE table approach and the reaction quotient, Q. Le Châtelier's principle explains how applied stresses disrupt equilibrium and predicts the system's response.
1. A liter of gasoline contains 8000 calories of energy. A person uses an average of 2000 calories per day. Excess calories are stored as fat.
2. Calorimetry is used to determine the energy content of substances by measuring heat changes. Specific heat and heat capacity allow calculation of heat from temperature changes.
3. Enthalpy (H) quantifies heat flow during chemical reactions. Standard enthalpies of formation provide a reference scale for enthalpy values.
This document discusses the effects of temperature on reaction rates and provides an explanation using collision theory and activation energy. It introduces the Arrhenius equation and shows how to use it to determine activation energy from rate constants measured at different temperatures. Catalysts are discussed as lowering the activation energy of reactions without being consumed. Enzymes are described as biological catalysts that regulate metabolic reaction speeds. An example problem determines activation energy for a temperature-dependent firefly flashing process using rate data.
Thermochemistry deals with the heat involved in chemical and physical changes. It is a branch of thermodynamics that studies energy and its transformations. Enthalpy (H) is a measure of the total energy of a system at constant pressure and can be used to determine the heat of a reaction. Calorimetry experiments allow measurement of heat changes through determination of temperature changes of a system and surroundings using equations such as q = cmΔT. Bomb calorimetry and coffee cup calorimetry are two common techniques used to directly measure the heat of chemical reactions.
Thermodynamics describes changes in heat and energy during chemical reactions and equilibria. It provides insight into reaction equilibrium, feasibility under conditions, and molecular bonding forces. The document discusses key thermodynamic concepts like open and closed systems, the laws of thermodynamics, enthalpy, entropy, and free energy - and how these can be used to determine if reactions will occur spontaneously. Living organisms are considered open systems that exchange heat and matter with their environments.
Thermodynamics describes changes in heat and energy during chemical reactions and equilibria. It provides insight into reaction equilibrium, feasibility under conditions, and molecular bonding forces. The document discusses key thermodynamic concepts like open and closed systems, the laws of thermodynamics, enthalpy, entropy, and free energy - and how these relate to biochemical reactions in living organisms.
Thermochemistry is the study of heat and energy changes in chemical and physical processes. It is concerned with energy changes that accompany physical and chemical processes at constant volume or constant pressure.
The first law of thermochemistry states that the quality of heat evolved or absorbed during a chemical reaction is the same, regardless of the pathway between the initial and final states. Hess's law states that the total enthalpy change for a reaction is the sum of the enthalpy changes for the individual steps of the reaction.
Enthalpy change (ΔH) of a reaction is the heat absorbed or released when one mole of the reaction occurs at constant pressure. It can be measured using a bomb calorimeter. Common standard
1) Bioenergetics examines the energy flow in living organisms using concepts like entropy, enthalpy, and free energy.
2) ATP acts as the energy currency of cells, being produced through exergonic reactions and consumed to power endergonic reactions.
3) Standard free energy changes can be added for coupled reactions and actual free energy depends on reactant and product concentrations, driving reactions towards or away from equilibrium.
Thermodynamics is the study of energy and its transformations. Thermochemistry is the subdiscipline involving chemical reactions and energy changes. The first law of thermodynamics states that energy is conserved as it transforms between forms. Energy exists in kinetic and potential forms. Kinetic energy is associated with motion, while potential energy is stored energy due to position or composition. Heat is the transfer of kinetic energy between objects of different temperatures until they reach equilibrium. Exothermic processes release heat from a system, while endothermic processes absorb heat into a system. Enthalpy changes (ΔH) quantify the heat absorbed or released by chemical reactions. Spontaneous processes are those that proceed without outside intervention, as dictated by a negative change
This document provides an overview of key concepts relating to chemical equilibrium including:
- Chemical equilibrium is the state where concentrations of reactants and products remain constant over time, though reactions are still occurring dynamically at the molecular level.
- The equilibrium constant, K, is a measure of the position of equilibrium and is defined by concentrations or pressures of products over reactants at equilibrium.
- For heterogeneous equilibria involving different phases, concentrations of pure solids and liquids are treated as constants not included in equilibrium expressions.
- The value of K indicates the extent to which a reaction proceeds - a large K means the reaction lies far to the right and goes essentially to completion, while a small K means the reaction lies far
Similar to Ch07lecture 150104200718-conversion-gate02 (20)
This document discusses suffixes and terminology used in medicine. It begins by listing common combining forms used to build medical terms and their meanings. It then defines several noun, adjective, and shorter suffixes and provides their meanings. Examples are given of medical terms built using combining forms and suffixes. The document also examines specific medical concepts in more depth, such as hernias, blood cells, acromegaly, splenomegaly, and laparoscopy.
The document is a chapter from a medical textbook that discusses anatomical terminology pertaining to the body as a whole. It defines the structural organization of the body from cells to tissues to organs to systems. It also describes the body cavities and identifies the major organs contained within each cavity, as well as anatomical divisions of the abdomen and back.
This document is from a textbook on medical terminology. It discusses the basic structure of medical words and how they are built from prefixes, suffixes, and combining forms. Some key points:
- Medical terms are made up of elements including roots, suffixes, prefixes, and combining vowels. Understanding these elements is important for analyzing terms.
- Common prefixes include hypo-, epi-, and cis-. Common suffixes include -itis, -algia, and -ectomy.
- Dozens of combining forms are provided, such as gastro- meaning stomach, cardi- meaning heart, and aden- meaning gland.
- Rules are provided for analyzing terms, such as reading from the suffix backward and dropping combining vowels before suffixes starting with vowels
This document is the copyright information for Chapter 25 on Cancer from the 6th edition of the textbook Molecular Cell Biology published in 2008 by W. H. Freeman and Company. The chapter was authored by a team that includes Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This document is the copyright information for Chapter 24 on Immunology from the 6th edition of the textbook Molecular Cell Biology published in 2008 by W. H. Freeman and Company. The chapter was authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
Nerve cells, also known as neurons, are highly specialized cells that process and transmit information through electrical and chemical signals. This chapter discusses the structure and function of neurons, how they communicate with each other via synapses, and how signals are propagated along neurons through changes in their membrane potentials. Neurons play a vital role in the nervous system by allowing organisms to process information and coordinate their responses.
This document is the copyright information for Chapter 22 from the 6th edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "The Molecular Cell Biology of Development" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This document is the copyright information for Chapter 21 from the sixth edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Cell Birth, Lineage, and Death" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This document is the copyright page for Chapter 20 from the 6th edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Regulating the Eukaryotic Cell Cycle" and is authored by a group of scientists including Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This document is the copyright information for Chapter 19 from the 6th edition textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Integrating Cells into Tissues" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This chapter discusses microtubules and intermediate filaments, which are types of cytoskeletal filaments that help organize and move cellular components. Microtubules are involved in processes like cell division and intracellular transport, while intermediate filaments provide mechanical strength and help integrate the nucleus with the cytoplasm. Together, these filaments play important structural and functional roles in eukaryotic cells.
This chapter discusses microfilaments, which are one of the three main types of cytoskeletal filaments found in eukaryotic cells. Microfilaments are composed of actin filaments and play important roles in cell motility, structure, and intracellular transport. They allow cells to change shape and to move by contracting or extending parts of the cell surface.
This document is the copyright page for Chapter 16 from the 6th edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Signaling Pathways that Control Gene Activity" and is authored by a group of scientists including Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh and Matsudaira.
This document is the copyright page for Chapter 15 of the 6th edition textbook "Molecular Cell Biology" by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira. It provides the chapter title "Cell Signaling I: Signal Transduction and Short-Term Cellular Responses" and notes the copyright is held by W. H. Freeman and Company in 2008.
This document is the copyright page for Chapter 14 from the 6th edition textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Vesicular Traffic, Secretion, and Endocytosis" and is authored by a group of scientists including Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh and Matsudaira.
This chapter discusses how proteins are transported into membranes and organelles within cells. Proteins destined for membranes or organelles have targeting signals that are recognized by transport systems. The transport systems then direct the proteins to their proper destinations, such as inserting membrane proteins into membranes or delivering soluble proteins into organelles.
This document is the copyright information for Chapter 12 from the sixth edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Cellular Energetics" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
This chapter discusses the transmembrane transport of ions and small molecules across cell membranes. It covers topics such as passive transport through membrane channels and pumps, as well as active transport using ATP. The chapter is from the 6th edition of the textbook Molecular Cell Biology and is copyrighted by W. H. Freeman and Company in 2008.
This document is the copyright information for Chapter 10, titled "Biomembrane Structure", from the sixth edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter was written by a team of authors including Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh and Matsudaira.
This document is the copyright information for Chapter 9 from the 6th edition of the textbook "Molecular Cell Biology" published in 2008 by W. H. Freeman and Company. The chapter is titled "Visualizing, Fractionating, and Culturing Cells" and is authored by Lodish, Berk, Kaiser, Krieger, Scott, Bretscher, Ploegh, and Matsudaira.
A workshop hosted by the South African Journal of Science aimed at postgraduate students and early career researchers with little or no experience in writing and publishing journal articles.
The simplified electron and muon model, Oscillating Spacetime: The Foundation...RitikBhardwaj56
Discover the Simplified Electron and Muon Model: A New Wave-Based Approach to Understanding Particles delves into a groundbreaking theory that presents electrons and muons as rotating soliton waves within oscillating spacetime. Geared towards students, researchers, and science buffs, this book breaks down complex ideas into simple explanations. It covers topics such as electron waves, temporal dynamics, and the implications of this model on particle physics. With clear illustrations and easy-to-follow explanations, readers will gain a new outlook on the universe's fundamental nature.
How to Manage Your Lost Opportunities in Odoo 17 CRMCeline George
Odoo 17 CRM allows us to track why we lose sales opportunities with "Lost Reasons." This helps analyze our sales process and identify areas for improvement. Here's how to configure lost reasons in Odoo 17 CRM
Strategies for Effective Upskilling is a presentation by Chinwendu Peace in a Your Skill Boost Masterclass organisation by the Excellence Foundation for South Sudan on 08th and 09th June 2024 from 1 PM to 3 PM on each day.
it describes the bony anatomy including the femoral head , acetabulum, labrum . also discusses the capsule , ligaments . muscle that act on the hip joint and the range of motion are outlined. factors affecting hip joint stability and weight transmission through the joint are summarized.
বাংলাদেশের অর্থনৈতিক সমীক্ষা ২০২৪ [Bangladesh Economic Review 2024 Bangla.pdf] কম্পিউটার , ট্যাব ও স্মার্ট ফোন ভার্সন সহ সম্পূর্ণ বাংলা ই-বুক বা pdf বই " সুচিপত্র ...বুকমার্ক মেনু 🔖 ও হাইপার লিংক মেনু 📝👆 যুক্ত ..
আমাদের সবার জন্য খুব খুব গুরুত্বপূর্ণ একটি বই ..বিসিএস, ব্যাংক, ইউনিভার্সিটি ভর্তি ও যে কোন প্রতিযোগিতা মূলক পরীক্ষার জন্য এর খুব ইম্পরট্যান্ট একটি বিষয় ...তাছাড়া বাংলাদেশের সাম্প্রতিক যে কোন ডাটা বা তথ্য এই বইতে পাবেন ...
তাই একজন নাগরিক হিসাবে এই তথ্য গুলো আপনার জানা প্রয়োজন ...।
বিসিএস ও ব্যাংক এর লিখিত পরীক্ষা ...+এছাড়া মাধ্যমিক ও উচ্চমাধ্যমিকের স্টুডেন্টদের জন্য অনেক কাজে আসবে ...
This presentation includes basic of PCOS their pathology and treatment and also Ayurveda correlation of PCOS and Ayurvedic line of treatment mentioned in classics.
हिंदी वर्णमाला पीपीटी, hindi alphabet PPT presentation, hindi varnamala PPT, Hindi Varnamala pdf, हिंदी स्वर, हिंदी व्यंजन, sikhiye hindi varnmala, dr. mulla adam ali, hindi language and literature, hindi alphabet with drawing, hindi alphabet pdf, hindi varnamala for childrens, hindi language, hindi varnamala practice for kids, https://www.drmullaadamali.com
Walmart Business+ and Spark Good for Nonprofits.pdfTechSoup
"Learn about all the ways Walmart supports nonprofit organizations.
You will hear from Liz Willett, the Head of Nonprofits, and hear about what Walmart is doing to help nonprofits, including Walmart Business and Spark Good. Walmart Business+ is a new offer for nonprofits that offers discounts and also streamlines nonprofits order and expense tracking, saving time and money.
The webinar may also give some examples on how nonprofits can best leverage Walmart Business+.
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Walmart Business + (https://business.walmart.com/plus) is a new shopping experience for nonprofits, schools, and local business customers that connects an exclusive online shopping experience to stores. Benefits include free delivery and shipping, a 'Spend Analytics” feature, special discounts, deals and tax-exempt shopping.
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Spark Good (walmart.com/sparkgood) is a charitable platform that enables nonprofits to receive donations directly from customers and associates.
Answers about how you can do more with Walmart!"
How to Add Chatter in the odoo 17 ERP ModuleCeline George
In Odoo, the chatter is like a chat tool that helps you work together on records. You can leave notes and track things, making it easier to talk with your team and partners. Inside chatter, all communication history, activity, and changes will be displayed.
This presentation was provided by Steph Pollock of The American Psychological Association’s Journals Program, and Damita Snow, of The American Society of Civil Engineers (ASCE), for the initial session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session One: 'Setting Expectations: a DEIA Primer,' was held June 6, 2024.
Main Java[All of the Base Concepts}.docxadhitya5119
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Executive Directors Chat Leveraging AI for Diversity, Equity, and InclusionTechSoup
Let’s explore the intersection of technology and equity in the final session of our DEI series. Discover how AI tools, like ChatGPT, can be used to support and enhance your nonprofit's DEI initiatives. Participants will gain insights into practical AI applications and get tips for leveraging technology to advance their DEI goals.
In this chapter, you will learn how to deduce and write chemical formulas and how to use the information incorporated into chemical formulas. The chapter ends with an overview of the relationship between names and formulas—chemical nomenclature.
Potassium reacts with water, liberating sufficient heat to ignite the hydrogen evolved. The transfer of heat between substances in chemical reactions is an important aspect of thermochemistry.
Thermochemistry is the branch of chemistry concerned with the heat effects that accompany chemical reactions. To understand the relationship between heat and chemical and physical changes, we must start with some basic definitions. We will then explore the concept of heat and the methods used to measure the transfer of energy across boundaries. Another form of energy transfer is work, and, in combination with heat, we will define the first law of thermodynamics.
Open system. The beaker of hot coffee transfers energy to the surroundings—it loses heat as it cools. Matter is also transferred in the form of water vapor.
Closed system. The flask of hot coffee transfers energy (heat) to the surroundings as it cools. Because the flask is stoppered, no water vapor escapes and no matter is transferred.
Isolated system. Hot coffee in an insulated container approximates an isolated system. No water vapor escapes, and, for a time at least, little heat is transferred to the surroundings. (Eventually, though, the coffee in the container cools to room temperature so this system is not completely isolated.)
Click 1 exposes the work formulae
Click 2 exposes the units of work, notice they are the same as the units of kinetic energy
Energy changes continuously from potential to kinetic.
Energy is lost to the surroundings.
A 150.0 g sample of lead is heated to the temperature of boiling water (100°C).
A 50.0 g sample of water is added to a thermally insulated beaker, and its temperature is found to be 22°C.
The hot lead is dumped into the cold water, and the temperature of the final lead–water mixture is 28.8 °C.
Can we explain why liquid water has a high specific heat? The answer is most certainly yes, but the explanation relies on concepts we have not yet discussed. The fact that water molecules form hydrogen bonds (which we discuss in Chapter 12) is an important part of the reason why water has a large specific heat value. Energy is stored in hydrogen bonds, particularly strong intermolecular interactions.
High Specific Heat of Compounds
Because of their greater complexity at the molecular level, compounds generally have more ways of storing internal energy than do the elements; they tend to have higher specific heats. Water, for example, has a specific heat that is more than 30 times as great as that of lead. We need a much larger quantity of heat to change the temperature of a sample of water than of an equal mass of a metal.
Lake Effect
An environmental consequence of the high specific heat of water is found in the effect of large lakes on local climates. Because a lake takes much longer to heat up in summer and cool down in winter than other types of terrain, lakeside communities tend to be cooler in summer and warmer in winter than communities more distant from the lake.
(a) An exothermic reaction. Slaked lime, Ca(OH)2 is produced by the action of water on quicklime, (CaO). The reactants are mixed at room temperature,
but the temperature of the mixture rises to 40.5°C
(b) An endothermic reaction. Ba(OH)2 • 8 H2O(s) and NH4Cl are mixed at room temperature, and the temperature falls to 5.8°C in the reaction which produces BaCl2•2 H2O and 2 NH3 and releasing 8 H2O.
see EXAMPLE 7-3 Using Bomb Calorimetry Data to Determine a Heat of Reaction
An iron wire is embedded in the sample in the lower half of the bomb. The bomb is assembled and filled with O2(g) at high pressure. The assembled bomb is immersed in water in the calorimeter, and the initial temperature is measured. A short pulse of electric current heats the sample, causing it to ignite. The final temperature of the calorimeter assembly is determined after the combustion. Because the bomb confines the reaction mixture to a fixed volume, the reaction is said to occur at constant volume. The significance of this fact is discussed on page 259.
see EXAMPLE 7-4 Determining a Heat of Reaction from Calorimetric Data
This figure is demonstrated in EXAMPLE 7-5 Calculating Pressure–Volume Work
In this hypothetical apparatus, a gas is confined by a massless piston of area A. A massless wire is attached to the piston and the gas is held back by two weights with a combined mass of 2M resting on the massless pan. The cylinder is immersed in a large water bath in order to keep the gas temperature constant. The initial state of the gas is P= 2Mg/A with a volume Vi at temperature, T.
When the external pressure on the confined gas is suddenly lowered by removing one of the weights the gas expands, pushing the piston up by the distance Dh, The increase in volume of the gas (DV) is the product of the cross-sectional area of the cylinder (A) and the distance (Dh). The final state of the gas is Pf = Mg/A, Vf, and T.
Negative sign is introduced for Pext because the system does work ON the surroundings.
When a gas expands V is positive and w is negative.
When a gas is compressed V is negative and w is positive, indicating that energy (as work) enters the system.
In many cases the external pressure is the same as the internal pressure of the system, so Pext is often just represented as P
The models represent water molecules, and the arrows represent the types of motion they can undergo. In the intermolecular attractions between water molecules, the symbols ∂+ and ∂- signify a separation of charge, producing centers of positive and negative charge that are smaller than ionic charges. These intermolecular attractions are discussed in Chapter 12.
Arrows represent the direction of heat flow (red arrow) and work (violet arrow). In the left diagram, the minus signs(-) signify
energy leaving the system and entering the surroundings. In the right diagram the plus signs (+) refer to energy entering the system from the surroundings. These sign conventions are consistent with the expression U = q + w.
EXAMPLE 7-6 Relating deltaU, q, and w Through the First Law of Thermodynamics illustrates these conventions.
Obtain three different samples of water:
1) one purified by extensive distillation of groundwater;
2) one synthesized by burning pure H2(g) in pure O2(g) and
3) one prepared by driving off the water of hydration from CuSO4•5H2O and condensing the gaseous water to a liquid.
The densities of the three different samples for the state that we specified will all be the same: 0.99820 g/mL
Thus, the value of a function of state depends on the state of the system, and not on how that state was established.
The difference in internal energy between these two states also has a unique value, ΔU = U2-U1
and this difference is something that we can precisely measure. It is the quantity of energy (as heat) that must be transferred from the surroundings to the system during the change from state 1 to state 2.
In the initial state there are four weights of mass M/2 holding the gas back. In the intermediate state one of these weights has been removed and in the final state a second weight of mass M/2 has been removed. The initial and final states in this figure are the same as in Figure 7-8. This two-step expansion helps us to establish that the work of expansion depends on the path taken.
In path (a), the volume of the system remains constant and no internal energy is converted into work—think of burning gasoline in a bomb calorimeter. In path (b), the system does work, so some of the internal energy change is used to do work—think of burning gasoline in an automobile engine to produce heat and work.
No work is performed at constant volume because the piston cannot move because of the stops placed through the cylinder walls;
qp = deltaU = -563.5 kJ
(b) When the reaction is carried out at constant pressure, the stops are removed. This allows the piston to move and the surroundings do work on the system, causing it to shrink into a smaller volume. More heat is evolved than in the constant-volume reaction;
qp = deltaH = -566.0 kJ.
Note that w is small. In most cases we use deltaH except for combustion reactions which use qv=deltaU
When a liquid is in contact with the atmosphere, energetic molecules at the surface of the liquid can overcome forces of attraction to their neighbors and pass into the gaseous, or vapor, state. We say that the liquid vaporizes. If the temperature of the liquid is to remain constant, the liquid must absorb heat from its surroundings to replace the energy carried off by the vaporizing molecules.
*The International Union of Pure and Applied Chemistry (IUPAC) recommended that the standard- state pressure be changed from 1 atm to 1 bar about 25 years ago, but some data tables are still based on the 1 atm standard. Fortunately, the differences in values resulting from this change in standard-state pressure are very small—almost always small enough to be ignored.
Horizontal lines represent absolute values of enthalpy. The higher a horizontal line, the greater the value of H that it represents. Vertical lines or arrows represent changes in enthalpy (delta H). Arrows pointing up signify increases in enthalpy—endothermic reactions. Arrows pointing down signify decreases in enthalpy—exothermic reactions.
Note that in summing the two equations NO(g), a species that would have appeared on both sides of the overall equation was canceled out. Also, because we used an enthalpy diagram, the superfluous term, ½ O2(g), entered in and then canceled out. We have just introduced Hess’s law, which states the following principle:
Absolute enthalpy cannot be determined.
H is a state function so changes in enthalpy, H, have unique values.
Reference forms of the elements in their standard states are the most stable form of the element at one bar and the given temperature.
The superscript degree symbol denotes that the enthalpy change is a standard enthalpy change and
The subscript “f” signifies that the reaction is one in which a substance is formed from its elements.
Although we can obtain bromine in either the gaseous or liquid state at 298.15 K, Br2 (l) is the most stable form. Br2(g) if obtained at 298.15 K and 1 bar pressure, immediately condenses to Br2(l).
Standard enthalpies of formation of elements are shown in the central plane, with ΔH°f=0. Substances with positive enthalpies of formation are above the plane, while those with negative enthalpies of formation are below the plane.
Enthalpy is a state function, hence ΔH° for the overall reaction 2 NaHCO3(s)is the sum of the
enthalpy changes for the two steps shown.
The symbol Σ (Greek, sigma) means “the sum of.” The terms that are added together are the products of the standard enthalpies of formation (∆H˚f) and their stoichiometric coefficients (ν), One sum is required for the reaction products (subscript p), and another for the initial reactants (subscript r). The enthalpy change of the reaction is the sum of terms for the products minus the sum of terms for the reactants.
Equation (7.21) avoids the manipulation of a number of chemical equations. The state function basis for equation (7.21) is shown in Figure 7-21 and is applied in Example 7-11 Calculating ∆H˚ from Tabulated Values of ∆H˚f .
We should also be able to calculate this enthalpy of neutralization by using enthalpy of formation data in expression (7.21), but this requires us to have enthalpy of formation data for individual ions. And there is a slight problem in getting these. We cannot create ions of a single type in a chemical reaction. We always produce cations and anions simultaneously, as in the reaction of sodium and chlorine to produce Na+ and Cl- in NaCl. We must choose a particular ion to which we assign an enthalpy of formation of zero in its aqueous solutions. We then compare the enthalpies of formation of other ions to this reference ion. The ion we arbitrarily choose for our zero is H+(aq) Now let us see how we can use expression (7.21) and data from equation (7.22) to determine the enthalpy of formation of OH-(aq)
These graphs show the history of energy consumption since 1970, with predictions to 2025. Petroleum (dark blue line) is seen to be the major source of energy for the foreseeable future, followed by coal (yellow) and natural gas (pink), which are about the same. Other sources of energy included are wind power (purple) and nuclear power (light blue). The unit BTU is a measure of energy and stands for British thermal unit (see Exercise 95).
[Source: www.eia.doe.gov/oiaf/ieo/pdf/ieoreftab_2.pdf]
(a) Some incoming radiation from sunlight is reflected back into space by the atmosphere, and some, such as certain UV light, is absorbed by stratospheric ozone. Much of the radiation from sunlight, however, reaches Earth’s surface. (b) Earth’s surface re-emits some of this energy as infrared radiation. (c) Infrared radiation leaving Earth’s atmosphere is less intense than that emitted by Earth’s surface because some of this radiation is absorbed by CO2 and other greenhouse gases and warms the atmosphere.
(a) The global average atmospheric carbon dioxide level over a 50-year span, expressed in parts per million by volume, as measured by a worldwide cooperative sampling network. (b) The actual and predicted CO2 emissions for a 55-year span due to the combustion of natural gas (pink line), coal (yellow), and petroleum (dark blue), together with the total of all CO2 emissions (light blue). The CO2 content of the atmosphere continues to increase, from approximately 375 ppm in 2003 to 385 ppm in 2008.