This document provides information about forms of energy and thermochemistry. It begins by defining energy and describing the main forms: mechanical, chemical, electromagnetic, heat (thermal), and nuclear energy. Kinetic, potential (elastic, chemical, gravitational), chemical, electromagnetic, and thermal energies are then explained in more detail. The document also discusses units of thermal energy, such as calories and joules, and how temperature is measured. Finally, it covers thermochemical equations, including how to determine if a reaction is endothermic or exothermic based on the sign of the enthalpy change (ΔH).
Predicting products of chemical reactionsCaraWhalen
The document discusses different types of chemical reactions including synthesis, decomposition, single displacement, double displacement, and combustion. It provides examples of each type of reaction using common reactants like Na, LiCl, Ca(OH)2, KBr, H2O, C2H6, O2, Ba, and S. Rules for determining products using the activity series on the periodic table and solubility rules are also covered.
Magnesium metal reacts with oxygen to produce magnesium oxide. Stoichiometry uses mole ratios derived from chemical equations to calculate amounts of substances involved in chemical reactions. For example, the mole ratio for the reaction 2Mg + O2 → 2MgO is 2:1:2. This can be used to determine that 4 moles of magnesium will react with oxygen to produce 4 moles of magnesium oxide. Stoichiometry problems can involve mass calculations using the formula that the number of moles equals the mass in grams divided by the molar mass in g/mol.
This document discusses stoichiometry, which uses balanced chemical equations to determine amounts of reactants and products in chemical reactions. It provides examples of using mole ratios from chemical equations to solve stoichiometry problems involving moles of substances or conversions between moles and grams. The key aspects are that chemical equations provide mole ratios that can be used as conversion factors, and problems must be worked in moles since equations relate substances in moles.
The document discusses reaction rates and kinetics. It defines factors that affect reaction rates such as concentration of reactants, physical state, temperature, and catalysts. It also describes methods for determining reaction rates by measuring changes in concentration over time. Rate laws relate the rate of reaction to concentrations of reactants through rate constants and reaction orders. Integrated rate laws can be used to determine concentrations of reactants over time for reactions of different orders.
This document discusses properties of aqueous solutions and acid-base reactions. It describes how ionic compounds and electrolytes dissolve in water, forming ions that are solvated. Precipitation reactions that form insoluble products are explained. Strong and weak acids and bases are defined, and neutralization reactions that produce salts and water are covered. Some acid-base reactions evolve gas as one of the products.
This document provides an overview of key concepts related to acids and bases in chemistry. It defines different types of acids and bases according to several theories. It also discusses properties of acids and bases such as tastes and colors of litmus paper. Strong and weak acids and bases are compared. Buffers are described as mixtures of weak acids and bases that resist pH change. The pH scale is introduced and methods for solving pH problems are outlined, including using Ka, Kb, and Kw values and ICE charts. Acid-base properties of salts and the principles of titrations are also summarized.
Predicting products of chemical reactionsCaraWhalen
The document discusses different types of chemical reactions including synthesis, decomposition, single displacement, double displacement, and combustion. It provides examples of each type of reaction using common reactants like Na, LiCl, Ca(OH)2, KBr, H2O, C2H6, O2, Ba, and S. Rules for determining products using the activity series on the periodic table and solubility rules are also covered.
Magnesium metal reacts with oxygen to produce magnesium oxide. Stoichiometry uses mole ratios derived from chemical equations to calculate amounts of substances involved in chemical reactions. For example, the mole ratio for the reaction 2Mg + O2 → 2MgO is 2:1:2. This can be used to determine that 4 moles of magnesium will react with oxygen to produce 4 moles of magnesium oxide. Stoichiometry problems can involve mass calculations using the formula that the number of moles equals the mass in grams divided by the molar mass in g/mol.
This document discusses stoichiometry, which uses balanced chemical equations to determine amounts of reactants and products in chemical reactions. It provides examples of using mole ratios from chemical equations to solve stoichiometry problems involving moles of substances or conversions between moles and grams. The key aspects are that chemical equations provide mole ratios that can be used as conversion factors, and problems must be worked in moles since equations relate substances in moles.
The document discusses reaction rates and kinetics. It defines factors that affect reaction rates such as concentration of reactants, physical state, temperature, and catalysts. It also describes methods for determining reaction rates by measuring changes in concentration over time. Rate laws relate the rate of reaction to concentrations of reactants through rate constants and reaction orders. Integrated rate laws can be used to determine concentrations of reactants over time for reactions of different orders.
This document discusses properties of aqueous solutions and acid-base reactions. It describes how ionic compounds and electrolytes dissolve in water, forming ions that are solvated. Precipitation reactions that form insoluble products are explained. Strong and weak acids and bases are defined, and neutralization reactions that produce salts and water are covered. Some acid-base reactions evolve gas as one of the products.
This document provides an overview of key concepts related to acids and bases in chemistry. It defines different types of acids and bases according to several theories. It also discusses properties of acids and bases such as tastes and colors of litmus paper. Strong and weak acids and bases are compared. Buffers are described as mixtures of weak acids and bases that resist pH change. The pH scale is introduced and methods for solving pH problems are outlined, including using Ka, Kb, and Kw values and ICE charts. Acid-base properties of salts and the principles of titrations are also summarized.
Energy required to beak a chemical bond, almost same amount of energy is used to form the same bond between reactants. Bond energies can be used to predict exothermic and endothermic nature of chemical reactions
Chem II - Kinetic Molecular Theory of Gases (Liquids and Solids)Lumen Learning
The document discusses the kinetic molecular theory of gases and its assumptions. It explains that gas molecules are in constant random motion, creating pressure through collisions with container walls. Pressure increases if volume decreases but temperature and moles remain constant due to more collisions per unit area. Temperature is a measure of average kinetic energy; higher temperature means higher average velocity and more collisions, transferring more energy to container walls. The theory relates macroscopic gas properties like pressure, volume and temperature to microscopic molecular behavior.
Phy351 ch 1 ideal law, gas law, condensed, triple point, van der waals eqMiza Kamaruzzaman
This document summarizes key concepts from Chapter 1 of PHY351 including:
1) The ideal gas law and how it relates pressure, volume, temperature and moles of gas. Real gases deviate from ideal behavior at low temperatures or high pressures.
2) Gas laws including Boyle's, Charles', and Gay-Lussac's laws and how the ideal gas law combines these relationships.
3) Concepts of absolute zero, the Kelvin temperature scale, and standard temperature and pressure.
4) Kinetic theory and how it relates gas properties to molecular motion, including molecular speed distributions and effects of temperature.
5) Phase diagrams and the different phases of matter as well as the triple point.
6
The document discusses the key characteristics and behaviors of gases. It introduces several gas laws including Boyle's law relating pressure and volume, Charles's law relating temperature and volume, Avogadro's law relating amount and volume, and Dalton's law of partial pressures. It derives the ideal gas equation and shows how it can be used to calculate gas properties like density from variables like molar mass, pressure, temperature.
Graham's Law of Diffusion states that the rates of diffusion of gases are inversely proportional to the square root of their densities. Under similar conditions of temperature and pressure, lighter gases will diffuse faster than heavier gases. The time taken for equal volumes of different gases to diffuse is directly proportional to the square roots of their molecular weights or densities. Graham's Law helps to separate gases based on differences in their densities and determine properties of unknown gases.
This document discusses chemical equilibrium, including definitions, characteristics, and factors that affect equilibrium. It defines chemical equilibrium as a state where the forward and reverse reaction rates are equal. Characteristics include the dynamic nature of equilibrium and constant concentrations of reactants and products at equilibrium. Factors that affect equilibrium position include concentration, pressure, temperature, and catalyst additions according to Le Chatelier's principle. The relationship between the equilibrium constant K and standard Gibbs free energy change ΔG° is also described.
This document discusses the three states of matter and gas laws. It explains that matter can exist as solids, liquids, or gases, and that gases are composed of particles with weak intermolecular forces that allow them to fill their container. It then describes several important gas laws, including Boyle's Law relating pressure and volume at constant temperature, Charles' Law relating volume and temperature at constant pressure, and Avogadro's Law relating volume and number of moles of gas. These gas laws apply to ideal gases and provide quantitative relationships between measurable gas properties.
This document provides an overview of key concepts in chemical bonding theories, including different types of bonds (ionic, covalent, polar covalent, metallic) and how they are formed. It also discusses bond polarity, electronegativity, isomers, resonance structures, sigma and pi bonds, and hybridization. Common characteristics of different bond types are outlined such as melting points, solubility, and conductivity. Examples are given to illustrate concepts like bond polarity, isomers, resonance structures, and counting sigma and pi bonds.
The document discusses stoichiometry and using mole ratios to calculate amounts of substances in a chemical reaction. It provides an example of using the mole ratio from a balanced chemical equation between iron (III) oxide and aluminum to calculate how many moles of aluminum are needed to fully react with a given amount of iron (III) oxide. It also works through an example of using a mole ratio to calculate the grams of sodium hydroxide needed to fully react with 3.10 grams of sulfuric acid based on the balanced equation. Mole ratios allow conversion between amounts of any two substances involved in a chemical reaction.
This document provides an overview of key concepts related to gases, including:
- The properties of ideal gases and units of pressure like pascals and atmospheres.
- Gas laws including Boyle's, Charles', Gay-Lussac's, Avogadro's, and the ideal gas law.
- Conditions of STP and using gas laws to perform stoichiometric calculations.
- The kinetic molecular theory which explains gas properties in terms of particle motion.
- How real gases differ from ideal gases due to intermolecular forces.
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.
The document summarizes key concepts from Chapter 12 of a chemistry textbook on stoichiometry. It discusses how to interpret and work with balanced chemical equations, including in terms of particles, moles, mass, and gas volume. It explains the concepts of limiting reagents, theoretical yield, actual yield and percent yield. Key steps for solving stoichiometry problems are outlined.
This document provides instructions for determining the molar volume of carbon dioxide gas through experiment. Students will measure the mass and volume of a CO2 gas sample under laboratory conditions. By calculating the mass of CO2 using the mass difference between an empty flask and one filled with CO2, and knowing the volume and temperature/pressure, students can use the ideal gas law to calculate the molar volume of CO2. The percentage error between the calculated and theoretical molar volume will also be determined to evaluate the accuracy of the experiment.
This document provides an overview of exothermic and endothermic reactions, calorimetry, and how to calculate enthalpy changes. It discusses key concepts like:
1) The standard enthalpy change (ΔH°) is the enthalpy change measured under standard conditions of temperature and pressure.
2) Calorimetry can be used to determine enthalpy changes by measuring the temperature change of a reaction mixture in a calorimeter.
3) Sample problems demonstrate how to use calorimetry data like temperature changes, masses, and concentrations to calculate enthalpy changes for chemical reactions.
This document provides an overview of thermochemistry topics covered in a physical chemistry course, including:
- Definitions of thermochemistry, thermochemical reactions, and heat of reaction
- Kirchoff's equation relating heat of reaction to temperature
- Calorimetry and bomb calorimetry for measuring heat changes
- Hess's law of constant heat summation and its applications
- Bond energies, enthalpies of formation, and using these values to calculate heat of reactions
The document discusses Hess's law, which states that the heat of reaction is the same whether a chemical process occurs in one or multiple steps. Specifically:
- Hess's law allows adding together multiple chemical equations to determine the enthalpy change of the overall equation.
- Two examples are provided to demonstrate calculating the enthalpy change of an overall reaction by combining individual reaction enthalpies.
- In both examples, the individual reactions are rearranged and combined to produce the overall reaction, and the enthalpy terms are summed to find the enthalpy change of the overall reaction.
This document provides a summary of key concepts for molecular geometry in high school chemistry according to the Valence Shell Electron Pair Repulsion (VSEPR) theory. It defines important terms like valence shell, Lewis structure, lone pair, and bonding pair. It also lists the electron and molecular geometries for molecules based on the number of electron regions around the central atom. Common molecular geometries include linear, trigonal planar, tetrahedral, trigonal pyramidal, bent, and octahedral. Examples are provided to illustrate how VSEPR theory predicts molecular geometry from electron geometry and ligand atoms.
The fundamentals of chemical equilibrium including Le Chatier's Principle and solved problems for heterogeneous and homogeneous equilibrium.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
Redox reactions involve the transfer of electrons between species. There are two types of agents involved - oxidizing agents that reduce other species by accepting electrons, and reducing agents that oxidize other species by donating electrons. Identification of redox reactions involves looking for a change in oxidation state between reactants and products. Balancing redox reactions uses the ion-electron method of writing and balancing half reactions for oxidation and reduction and combining them. Organic redox reactions use a similar process by writing oxidation and reduction half reactions and balancing mass, charge, and electrons.
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 slide show accompanies the learner guide "Mechanical Technology Grade 10" by Charles Goodwin, Andre Lategan & Daniel Meyer, published by Future Managers Pty Ltd. For more information visit our website www.futuremanagers.net
Heat can be transferred between two systems in three modes: conduction, convection, and radiation. In a heat exchanger, heat is transferred when two fluids at different temperatures flow through the exchanger. The rate of heat transfer depends on the overall heat transfer coefficient, which takes into account the resistances to heat transfer through the solid wall and boundary layers of each fluid. Common types of heat exchangers include shell-and-tube, plate, compact, regenerative, and cross-flow exchangers. The selection of a heat exchanger depends on factors like the fluids used, temperatures, pressures, and space requirements.
Energy required to beak a chemical bond, almost same amount of energy is used to form the same bond between reactants. Bond energies can be used to predict exothermic and endothermic nature of chemical reactions
Chem II - Kinetic Molecular Theory of Gases (Liquids and Solids)Lumen Learning
The document discusses the kinetic molecular theory of gases and its assumptions. It explains that gas molecules are in constant random motion, creating pressure through collisions with container walls. Pressure increases if volume decreases but temperature and moles remain constant due to more collisions per unit area. Temperature is a measure of average kinetic energy; higher temperature means higher average velocity and more collisions, transferring more energy to container walls. The theory relates macroscopic gas properties like pressure, volume and temperature to microscopic molecular behavior.
Phy351 ch 1 ideal law, gas law, condensed, triple point, van der waals eqMiza Kamaruzzaman
This document summarizes key concepts from Chapter 1 of PHY351 including:
1) The ideal gas law and how it relates pressure, volume, temperature and moles of gas. Real gases deviate from ideal behavior at low temperatures or high pressures.
2) Gas laws including Boyle's, Charles', and Gay-Lussac's laws and how the ideal gas law combines these relationships.
3) Concepts of absolute zero, the Kelvin temperature scale, and standard temperature and pressure.
4) Kinetic theory and how it relates gas properties to molecular motion, including molecular speed distributions and effects of temperature.
5) Phase diagrams and the different phases of matter as well as the triple point.
6
The document discusses the key characteristics and behaviors of gases. It introduces several gas laws including Boyle's law relating pressure and volume, Charles's law relating temperature and volume, Avogadro's law relating amount and volume, and Dalton's law of partial pressures. It derives the ideal gas equation and shows how it can be used to calculate gas properties like density from variables like molar mass, pressure, temperature.
Graham's Law of Diffusion states that the rates of diffusion of gases are inversely proportional to the square root of their densities. Under similar conditions of temperature and pressure, lighter gases will diffuse faster than heavier gases. The time taken for equal volumes of different gases to diffuse is directly proportional to the square roots of their molecular weights or densities. Graham's Law helps to separate gases based on differences in their densities and determine properties of unknown gases.
This document discusses chemical equilibrium, including definitions, characteristics, and factors that affect equilibrium. It defines chemical equilibrium as a state where the forward and reverse reaction rates are equal. Characteristics include the dynamic nature of equilibrium and constant concentrations of reactants and products at equilibrium. Factors that affect equilibrium position include concentration, pressure, temperature, and catalyst additions according to Le Chatelier's principle. The relationship between the equilibrium constant K and standard Gibbs free energy change ΔG° is also described.
This document discusses the three states of matter and gas laws. It explains that matter can exist as solids, liquids, or gases, and that gases are composed of particles with weak intermolecular forces that allow them to fill their container. It then describes several important gas laws, including Boyle's Law relating pressure and volume at constant temperature, Charles' Law relating volume and temperature at constant pressure, and Avogadro's Law relating volume and number of moles of gas. These gas laws apply to ideal gases and provide quantitative relationships between measurable gas properties.
This document provides an overview of key concepts in chemical bonding theories, including different types of bonds (ionic, covalent, polar covalent, metallic) and how they are formed. It also discusses bond polarity, electronegativity, isomers, resonance structures, sigma and pi bonds, and hybridization. Common characteristics of different bond types are outlined such as melting points, solubility, and conductivity. Examples are given to illustrate concepts like bond polarity, isomers, resonance structures, and counting sigma and pi bonds.
The document discusses stoichiometry and using mole ratios to calculate amounts of substances in a chemical reaction. It provides an example of using the mole ratio from a balanced chemical equation between iron (III) oxide and aluminum to calculate how many moles of aluminum are needed to fully react with a given amount of iron (III) oxide. It also works through an example of using a mole ratio to calculate the grams of sodium hydroxide needed to fully react with 3.10 grams of sulfuric acid based on the balanced equation. Mole ratios allow conversion between amounts of any two substances involved in a chemical reaction.
This document provides an overview of key concepts related to gases, including:
- The properties of ideal gases and units of pressure like pascals and atmospheres.
- Gas laws including Boyle's, Charles', Gay-Lussac's, Avogadro's, and the ideal gas law.
- Conditions of STP and using gas laws to perform stoichiometric calculations.
- The kinetic molecular theory which explains gas properties in terms of particle motion.
- How real gases differ from ideal gases due to intermolecular forces.
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.
The document summarizes key concepts from Chapter 12 of a chemistry textbook on stoichiometry. It discusses how to interpret and work with balanced chemical equations, including in terms of particles, moles, mass, and gas volume. It explains the concepts of limiting reagents, theoretical yield, actual yield and percent yield. Key steps for solving stoichiometry problems are outlined.
This document provides instructions for determining the molar volume of carbon dioxide gas through experiment. Students will measure the mass and volume of a CO2 gas sample under laboratory conditions. By calculating the mass of CO2 using the mass difference between an empty flask and one filled with CO2, and knowing the volume and temperature/pressure, students can use the ideal gas law to calculate the molar volume of CO2. The percentage error between the calculated and theoretical molar volume will also be determined to evaluate the accuracy of the experiment.
This document provides an overview of exothermic and endothermic reactions, calorimetry, and how to calculate enthalpy changes. It discusses key concepts like:
1) The standard enthalpy change (ΔH°) is the enthalpy change measured under standard conditions of temperature and pressure.
2) Calorimetry can be used to determine enthalpy changes by measuring the temperature change of a reaction mixture in a calorimeter.
3) Sample problems demonstrate how to use calorimetry data like temperature changes, masses, and concentrations to calculate enthalpy changes for chemical reactions.
This document provides an overview of thermochemistry topics covered in a physical chemistry course, including:
- Definitions of thermochemistry, thermochemical reactions, and heat of reaction
- Kirchoff's equation relating heat of reaction to temperature
- Calorimetry and bomb calorimetry for measuring heat changes
- Hess's law of constant heat summation and its applications
- Bond energies, enthalpies of formation, and using these values to calculate heat of reactions
The document discusses Hess's law, which states that the heat of reaction is the same whether a chemical process occurs in one or multiple steps. Specifically:
- Hess's law allows adding together multiple chemical equations to determine the enthalpy change of the overall equation.
- Two examples are provided to demonstrate calculating the enthalpy change of an overall reaction by combining individual reaction enthalpies.
- In both examples, the individual reactions are rearranged and combined to produce the overall reaction, and the enthalpy terms are summed to find the enthalpy change of the overall reaction.
This document provides a summary of key concepts for molecular geometry in high school chemistry according to the Valence Shell Electron Pair Repulsion (VSEPR) theory. It defines important terms like valence shell, Lewis structure, lone pair, and bonding pair. It also lists the electron and molecular geometries for molecules based on the number of electron regions around the central atom. Common molecular geometries include linear, trigonal planar, tetrahedral, trigonal pyramidal, bent, and octahedral. Examples are provided to illustrate how VSEPR theory predicts molecular geometry from electron geometry and ligand atoms.
The fundamentals of chemical equilibrium including Le Chatier's Principle and solved problems for heterogeneous and homogeneous equilibrium.
**More good stuff available at:
www.wsautter.com
and
http://www.youtube.com/results?search_query=wnsautter&aq=f
Redox reactions involve the transfer of electrons between species. There are two types of agents involved - oxidizing agents that reduce other species by accepting electrons, and reducing agents that oxidize other species by donating electrons. Identification of redox reactions involves looking for a change in oxidation state between reactants and products. Balancing redox reactions uses the ion-electron method of writing and balancing half reactions for oxidation and reduction and combining them. Organic redox reactions use a similar process by writing oxidation and reduction half reactions and balancing mass, charge, and electrons.
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 slide show accompanies the learner guide "Mechanical Technology Grade 10" by Charles Goodwin, Andre Lategan & Daniel Meyer, published by Future Managers Pty Ltd. For more information visit our website www.futuremanagers.net
Heat can be transferred between two systems in three modes: conduction, convection, and radiation. In a heat exchanger, heat is transferred when two fluids at different temperatures flow through the exchanger. The rate of heat transfer depends on the overall heat transfer coefficient, which takes into account the resistances to heat transfer through the solid wall and boundary layers of each fluid. Common types of heat exchangers include shell-and-tube, plate, compact, regenerative, and cross-flow exchangers. The selection of a heat exchanger depends on factors like the fluids used, temperatures, pressures, and space requirements.
The document discusses the basic mechanisms of heat transfer, which are conduction, convection, and radiation. It describes conduction as the transfer of energy between particles through interactions and collisions. Conduction in solids is explained to occur through molecular vibrations and electron transport. Fourier's law of heat conduction establishes that the rate of heat conduction through a material is proportional to the thermal conductivity, temperature gradient, and area, while being inversely proportional to thickness. Thermal conductivity is introduced as a measure of a material's ability to conduct heat.
This document discusses heat transfer and heat exchangers. It defines key units used in heat transfer such as temperature, heat, and heat capacity. It describes different types of heat including latent heat and methods of heat transfer including conduction, convection, and radiation. Specifically, it explains that heat is transferred through conduction by the movement of free electrons in metals and vibration of atoms/molecules, with the rate of conduction determined by thermal conductivity. It also provides examples of thermal conductivity values for common materials.
This document discusses heat transfer, including:
1. The three modes of heat transfer - conduction, convection, and radiation. It provides equations to calculate heat transfer via these modes.
2. Key heat transfer concepts like thermal conductivity, convection coefficients, emissivity, and overall heat transfer coefficients.
3. Examples of calculating heat transfer through composite walls and heat exchanger surfaces.
The document discusses heat transfer through conduction, convection and radiation. It covers key concepts like Fourier's law of heat conduction, thermal conductivity of solids, liquids and gases, one dimensional and radial heat conduction, and heat transfer through composite walls. It also provides examples of calculating heat transfer through plane and cylindrical walls, determining the required thickness of insulation, and calculating critical thickness of insulation.
Heat and temperature are often confused but refer to different concepts. Temperature is a measure of the average kinetic energy of molecular motion in a substance, while heat is the transfer of energy between objects due to a temperature difference. Several factors affect heat and temperature, including the movement of molecules. Common temperature scales include Celsius, Fahrenheit and Kelvin, and formulas can be used to convert between them. Proper use of thermometers allows accurate measurement of temperature.
This document provides an overview of thermochemistry and key concepts related to heat and energy transfers during chemical and physical processes. It defines important terms like heat, temperature, enthalpy, and heat capacity. It also distinguishes between endothermic and exothermic reactions, and describes heat changes associated with phase changes like melting, vaporization, solidification, and condensation. Specific concepts covered include Hess's law of heat summation, standard heats of formation and reaction, and calculating heat changes using thermochemical data.
This document discusses the history and theory of heat. It begins by describing the early caloric theory which viewed heat as the flow of a fluid called caloric. It then discusses how the calorie, still used today, was named after this theory. Later sections describe experiments by Rumford and Joule establishing that heat represents the transfer of energy. Specific concepts covered include the mechanical equivalent of heat, distinctions between temperature, heat and internal energy, calculations of specific heat and latent heat, and the three modes of heat transfer - conduction, convection and radiation. Equations for quantifying these concepts are also provided.
Energy can exist in various forms, including heat and chemical bond energy. Heat is the kinetic energy of atomic and molecular motion, and is transferred from hotter to colder objects. Chemical bond energy is the potential energy stored in the attractive forces between bonded atoms and molecules. During chemical reactions, bond energy is converted to kinetic energy in the form of heat or motion. Calorimetry experiments allow measurement of heat changes to determine if reactions are exothermic (release heat) or endothermic (absorb heat).
This chapter discusses key concepts in heat and thermodynamics including:
- Temperature scales and the zeroth law of thermodynamics which defines temperature.
- The differences between heat and work as means of energy transfer.
- Specific heat, which is the energy required to change an object's temperature, and latent heat, which is energy absorbed or released during phase changes with no temperature change.
- Methods of heat transfer including conduction, convection and radiation. Conduction involves direct contact while convection involves fluid movement and radiation involves electromagnetic waves.
Thermal energy, temperature, and heat are defined. Thermal energy depends on temperature, number of particles, and particle arrangement. Temperature is a measure of how hot or cold something is, while heat is the transfer of thermal energy between systems. Temperature is measured in Kelvin using a thermometer, while heat is measured in Joules using a calorimeter. Systems reach thermal equilibrium when there is no net heat transfer between them. The three laws of thermodynamics are also summarized.
This document discusses key concepts in thermal physics including:
- Energy transformations like work and heat, with heat defined as the non-mechanical transfer of energy due to a temperature difference.
- The first law of thermodynamics which states that the change in internal energy of a system equals the net work and heat transfers.
- Concepts like temperature, thermal energy, and heat transfer via conduction until thermal equilibrium is reached.
- Definitions of the thermodynamic temperature scale with absolute zero at 0K and the specific heat capacity which quantifies the energy required to change an object's temperature.
This document defines key concepts related to heat transfer including:
- Heat is the transfer of energy between objects due to temperature differences and is measured in Joules.
- Temperature is determined by the motion of particles in a substance, with faster motion indicating a higher temperature.
- The three primary methods of heat transfer are conduction, convection, and radiation. Conduction involves direct contact, convection involves the transfer of heat by a liquid or gas, and radiation involves the transfer of heat through electromagnetic waves.
- Equations are provided to calculate heat transfer via conduction, convection, and radiation based on factors like thermal conductivity, heat transfer coefficient, surface area, and temperature differences.
The document discusses several key concepts related to temperature and heat:
1. It defines temperature as a measure of the average kinetic energy of molecules, while heat is the total thermal energy within an object.
2. It explains concepts such as specific heat capacity, which is the amount of energy required to raise the temperature of a substance, and latent heat, which is the energy required for phase changes without a change in temperature.
3. It discusses various types of thermometers and temperature scales, and provides examples of calculating heat transfer and temperature change using equations for specific heat, latent heat, and thermal expansion.
Heat is a form of energy that is transferred between objects in contact with each other or at different temperatures. There are three main mechanisms of heat transfer: conduction, convection, and radiation. Conduction requires physical contact, convection occurs through the motion of fluids, and radiation can occur through empty space. Temperature is a measure of the average kinetic energy of molecular motion and is measured using thermometers on standardized scales like Celsius and Kelvin. The amount of heat required to change the temperature of a substance depends on its specific heat. Architectural design can influence heat transfer through a building's envelope and systems.
1. Thermochemistry examines energy changes that occur during chemical reactions and changes in state.
2. Energy can be transferred as heat or work. Exothermic processes release heat to the surroundings while endothermic processes absorb heat from the surroundings.
3. The specific heat of a substance depends on its mass and chemical composition and determines how much its temperature changes when heat is added or removed. Water has a high specific heat.
1. The document discusses heat transfer and related concepts including matter, energy, temperature, and the different types of heat transfer.
2. It defines key terms like thermal energy, temperature, heat, conduction, convection, and radiation. Thermal energy is the kinetic energy of particles, temperature measures thermal energy, and heat is the transfer of thermal energy between objects.
3. Heat transfer occurs through conduction, convection, or radiation. Conduction requires contact, convection occurs through fluid movement, and radiation transfers heat through electromagnetic waves without contact.
Heat is the transfer of thermal energy between objects due to a temperature difference. Temperature is a measure of the average kinetic energy of particles in a substance and is measured using a thermometer. Heat is transferred between objects via conduction, convection, or radiation. Thermal expansion occurs when the temperature of an object increases, causing the particles to vibrate faster and the object to expand in length, area, or volume. Energy exists in various forms and can be transferred and transformed between forms, but the total energy in a closed system remains constant according to the law of conservation of energy.
1. Thermochemistry is the study of heat changes that occur during chemical reactions and physical changes of state. It uses concepts such as exothermic and endothermic reactions, enthalpy, and calorimetry.
2. Hess's law states that the heat change of a reaction is equal to the sum of the heat changes of the steps forming that reaction. This allows for calculation of heats of reaction from standard heats of formation.
3. Calorimetry is used to directly measure heat changes through the use of calorimeters. Thermochemical equations contain the balanced chemical equation and associated heat change.
The document discusses different types of energy including potential energy, kinetic energy, and thermal energy. It defines key energy concepts such as work, heat, temperature, and the laws of thermodynamics. Specifically, it explains that (1) energy can change forms but is never created or destroyed, (2) heat is the transfer of energy between objects at different temperatures until they reach thermal equilibrium, and (3) the amount of energy required to change an object's temperature depends on its specific heat capacity and mass.
This summary provides an overview of key concepts about thermal energy and temperature from the document:
The document discusses different theories of heat and temperature over time, from the caloric theory to the modern kinetic molecular theory. It also explains concepts such as thermal energy, temperature, heat transfer through conduction, convection and radiation, specific heat, and changes of state. The first and second laws of thermodynamics are introduced, with the first law stating that thermal energy can increase through heat or work, and the second law stating that natural processes increase the total entropy of the universe.
This document provides instructions for navigating a presentation on thermodynamics. It begins with directions for viewing the presentation as a slideshow and advancing through it. It then lists the chapter contents which include sections on temperature, heat, and changes in temperature and phase. The remainder of the document consists of slides from the presentation covering these topics, including definitions of key terms, examples, and sample problems.
The document discusses energy and its various forms. It states that energy is required for physical and chemical changes to occur in matter and is either absorbed or released during these changes. The law of conservation of energy holds that the total energy in a system remains constant during any physical or chemical change. Energy can be transferred between objects in different forms, including heat, which is the transfer of energy between objects at different temperatures. Temperature is defined as the average kinetic energy of particles and is measured on different scales like Celsius, Fahrenheit and Kelvin.
ESPP presentation to EU Waste Water Network, 4th June 2024 “EU policies driving nutrient removal and recycling
and the revised UWWTD (Urban Waste Water Treatment Directive)”
Travis Hills' Endeavors in Minnesota: Fostering Environmental and Economic Pr...Travis Hills MN
Travis Hills of Minnesota developed a method to convert waste into high-value dry fertilizer, significantly enriching soil quality. By providing farmers with a valuable resource derived from waste, Travis Hills helps enhance farm profitability while promoting environmental stewardship. Travis Hills' sustainable practices lead to cost savings and increased revenue for farmers by improving resource efficiency and reducing waste.
BREEDING METHODS FOR DISEASE RESISTANCE.pptxRASHMI M G
Plant breeding for disease resistance is a strategy to reduce crop losses caused by disease. Plants have an innate immune system that allows them to recognize pathogens and provide resistance. However, breeding for long-lasting resistance often involves combining multiple resistance genes
Phenomics assisted breeding in crop improvementIshaGoswami9
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change, and increasing global population, crop yield and quality need to be improved in a sustainable way over the coming decades. Genetic improvement by breeding is the best way to increase crop productivity. With the rapid progression of functional
genomics, an increasing number of crop genomes have been sequenced and dozens of genes influencing key agronomic traits have been identified. However, current genome sequence information has not been adequately exploited for understanding
the complex characteristics of multiple gene, owing to a lack of crop phenotypic data. Efficient, automatic, and accurate technologies and platforms that can capture phenotypic data that can
be linked to genomics information for crop improvement at all growth stages have become as important as genotyping. Thus,
high-throughput phenotyping has become the major bottleneck restricting crop breeding. Plant phenomics has been defined as the high-throughput, accurate acquisition and analysis of multi-dimensional phenotypes
during crop growing stages at the organism level, including the cell, tissue, organ, individual plant, plot, and field levels. With the rapid development of novel sensors, imaging technology,
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This presentation explores a brief idea about the structural and functional attributes of nucleotides, the structure and function of genetic materials along with the impact of UV rays and pH upon them.
When I was asked to give a companion lecture in support of ‘The Philosophy of Science’ (https://shorturl.at/4pUXz) I decided not to walk through the detail of the many methodologies in order of use. Instead, I chose to employ a long standing, and ongoing, scientific development as an exemplar. And so, I chose the ever evolving story of Thermodynamics as a scientific investigation at its best.
Conducted over a period of >200 years, Thermodynamics R&D, and application, benefitted from the highest levels of professionalism, collaboration, and technical thoroughness. New layers of application, methodology, and practice were made possible by the progressive advance of technology. In turn, this has seen measurement and modelling accuracy continually improved at a micro and macro level.
Perhaps most importantly, Thermodynamics rapidly became a primary tool in the advance of applied science/engineering/technology, spanning micro-tech, to aerospace and cosmology. I can think of no better a story to illustrate the breadth of scientific methodologies and applications at their best.
Remote Sensing and Computational, Evolutionary, Supercomputing, and Intellige...University of Maribor
Slides from talk:
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MW disc within the last 3 Gyr. These two scenarios make different predictions about observable structure in local phase space,
because the morphology of debris depends on how long it has had to phase mix. The recently identified phase-space folds in Gaia
DR3 have positive caustic velocities, making them fundamentally different than the phase-mixed chevrons found in simulations
at late times. Roughly 20 per cent of the stars in the prograde local stellar halo are associated with the observed caustics. Based
on a simple phase-mixing model, the observed number of caustics are consistent with a merger that occurred 1–2 Gyr ago.
We also compare the observed phase-space distribution to FIRE-2 Latte simulations of GSE-like mergers, using a quantitative
measurement of phase mixing (2D causticality). The observed local phase-space distribution best matches the simulated data
1–2 Gyr after collision, and certainly not later than 3 Gyr. This is further evidence that the progenitor of the ‘last major merger’
did not collide with the MW proto-disc at early times, as is thought for the GSE, but instead collided with the MW disc within
the last few Gyr, consistent with the body of work surrounding the VRM.
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equations sourced by a topological defect, i.e. a singularity of a very specific form, the result is a localized gravitational
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spherical shell without any underlying mass. Moreover, a large-scale structure which exploits this solution by assembling
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mitigated, at least in part.
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Although Artemia has been known to man for centuries, its use as a food for the culture of larval organisms apparently began only in the 1930s, when several investigators found that it made an excellent food for newly hatched fish larvae (Litvinenko et al., 2023). As aquaculture developed in the 1960s and ‘70s, the use of Artemia also became more widespread, due both to its convenience and to its nutritional value for larval organisms (Arenas-Pardo et al., 2024). The fact that Artemia dormant cysts can be stored for long periods in cans, and then used as an off-the-shelf food requiring only 24 h of incubation makes them the most convenient, least labor-intensive, live food available for aquaculture (Sorgeloos & Roubach, 2021). The nutritional value of Artemia, especially for marine organisms, is not constant, but varies both geographically and temporally. During the last decade, however, both the causes of Artemia nutritional variability and methods to improve poorquality Artemia have been identified (Loufi et al., 2024).
Brine shrimp (Artemia spp.) are used in marine aquaculture worldwide. Annually, more than 2,000 metric tons of dry cysts are used for cultivation of fish, crustacean, and shellfish larva. Brine shrimp are important to aquaculture because newly hatched brine shrimp nauplii (larvae) provide a food source for many fish fry (Mozanzadeh et al., 2021). Culture and harvesting of brine shrimp eggs represents another aspect of the aquaculture industry. Nauplii and metanauplii of Artemia, commonly known as brine shrimp, play a crucial role in aquaculture due to their nutritional value and suitability as live feed for many aquatic species, particularly in larval stages (Sorgeloos & Roubach, 2021).
ESR spectroscopy in liquid food and beverages.pptxPRIYANKA PATEL
With increasing population, people need to rely on packaged food stuffs. Packaging of food materials requires the preservation of food. There are various methods for the treatment of food to preserve them and irradiation treatment of food is one of them. It is the most common and the most harmless method for the food preservation as it does not alter the necessary micronutrients of food materials. Although irradiated food doesn’t cause any harm to the human health but still the quality assessment of food is required to provide consumers with necessary information about the food. ESR spectroscopy is the most sophisticated way to investigate the quality of the food and the free radicals induced during the processing of the food. ESR spin trapping technique is useful for the detection of highly unstable radicals in the food. The antioxidant capability of liquid food and beverages in mainly performed by spin trapping technique.
2. I. Forms of Energy
II. Law of Conservation of Energy & Heat Transfer
III. Thermochemical Equations
IV. Specific Heat
V. Calorimetry
Table of Contents2
3. Understanding Energy and
it Forms
C.11.A Understand energy and its
forms, including kinetic energy,
potential energy, and thermal
energy. 3
4. ENERGY
• Energy is the measure of the ability to
cause change to occur (work)
• The property of an object that enables
it to do work
Units of energy:
Joule (J) = newton x meter
J = N x m
4
5. Types of Energy
Energy appears in many forms. There are five
main forms of energy:
Mechanical (Kinetic and Potential)
Chemical
Electromagnetic
Heat (Thermal)
Nuclear
5
6. Kinetic Energy
• Kinetic energy is energy of motion.
• Kinetic energy depends on both mass
and velocity.
• The faster the object moves- the more
kinetic energy
6
7. Potential Energy
• The amount of energy that is
stored
• 3 types of potential energy
• Elastic
• Ex. Pulling a rubber band back and
holding
• Chemical
• Ex. Burning a match
• Gravitational
• A bolder resting on top of a hill
• Objects at high positions have greater
gravitational potential energy then
objects in lower positions 7
8. Chemical Energy
• Chemical energy is the energy stored in the bonds of
atoms and molecules.
• This a form of potential energy until the bonds are
broken.
• Fossil fuels and biomass store chemical energy.
Examples:
• Digesting food…bonds are
• broken to release energy for
• your body to store and use.
• • Sports… your body uses energy
• stored in your muscles obtained
• from food.
• • Fire–a chemical change.
8
9. Electromagnetic Energy
• a form of energy that is reflected or emitted
from objects in the form of electrical and
magnetic waves that can travel through space
• Moving electric charges
Examples:
• Power lines carry electricity
• Electric motors are driven by electromagnetic
energy
• Light is this form of energy (X-rays, radio
• waves, laser light etc.)
9
10. Thermal Energy
The internal energy or thermal energy of a substance
is determined by the movement of the molecules
and the potential energy of the arrangement of
molecules.
• Temperature is the measure of the
average kinetic energy of the
molecules.
• Heat energy is the energy transferred
from a warmer substance to a
colder one by the collisions of
molecules.
10
11. Units of Thermal Energy
• The unit for all energy is the joule.
• However, sometimes the calorie is used for heat.
• The calorie is defined as the amount of heat needed to
raise 1 g of a substance 1 degree Celsius.
• A Calorie (food calorie, with a capital C) is 1000 cal
1 cal = 4.18 joules or 1kcal = 4180 J
To convert calories to
joules multiply the calories
by
4.18.
To convert joules to
calories
divide by 4.18.
11
12. Nuclear Energy
• When the nucleus of an atom splits,
nuclear energy is released.
• Nuclear energy is the most concentrated
form of energy.
• Fission/fusion
12
14. Chem.11B Understand the law of conservation of
energy and the processes of heat transfer.
14
15. Conservation of energy (1st
law of thermodynamics) is one
of several conservation laws.
It states that the total inflow
of energy into a system must
equal the total outflow of
energy from the system
In other words, energy can be
converted from one form to
another, but it cannot be
created or destroyed.
15
16. The law of conservation of energy is also true
of heat energy.
If a substance gets hotter something else
must get colder.
heatlost = heatgained
For example 200 g of water at 80 degrees C is mixed
with 200 g of water at 10 degree C.What is the final
temperature?
The 80 degree water will lose heat and the 10 degree
water will gain heat.They will eventually come to
thermal equilibrium and be at the same
temperature.
16
17. Heat, q, is energy that transfers from one
object to another because of a temperature
difference.
The transfer of energy always takes place
from a substance at a high temperature to a
substance at a lower temperature.
17
18. Example :You are holding a hot water bottle
what will happen:
▪ The warmer object (hot water bottle) will transfer
energy to the cooler object (your hand).
▪ When energy is transferred as heat, the temperature of
the water falls while the temperature of your skin rises.
▪ The great the difference in temperature of the two
object, the more energy that will be transferred.
▪ This explains why hot things always cool down.
18
19. The internal energy or thermal energy of a substance is
determined by the movement of the molecules and the
potential energy of the arrangement of molecules.
Temperature measures the average kinetic energy of the
particles in a sample of matter
(Kinetic Energy = ½ mv2).
The greater the kinetic energy (the faster the molecules are
moving), the higher the temperature, and the hotter it feels.
When the kinetic energy decreases (molecules slow down),
the temperature decreases.
A substance can change in temperature due to heat transfer.
19
20. Thermometers are device that is used
to measure kinetic energy not
temperature.
Thermometers rely on a simple
physical property of all substances
MOST OBJECTS EXPAND WHENTHEIR
TEMPERATURE INCREASES
Thermometers use liquids substance like
mercury and colored alcohol that
expand as their temperatures increase
and contract as temperature decreases 20
21. Fahrenheit Scale
Most familiar to you from your friendly weather reports
Units called DEGREES FAHRENHEIT [ °F]
Water freezes at 32 °F and Boils at 212 °F
Celsius Scale
Widely used in science and other countries
Units called DEGREES CELSIUS [°C]
Celsius scale is based the values of 0 °C to freezing point of water and a
value of 100 °C to boiling point of water (at standard pressure)
Kelvin Scale
Based on absolute zero the temperature at which an objects energy is
minimal
Units called KELVIN [K]
On the Kelvin scale zero Kelvin is absolute zero 21
22. Energy transfer as heat from a hot object can occur in 3
ways
Conduction
Convection
Radiation
Heat transfer will stop when thermal equilibrium is
reached, that is the rate at which energy flows out of a
substance equals the rate that energy flows into the
substance.
22
23. The transfer of energy as heat between particles as
they collide with a substance or between 2 objects in
contact
Energy transfer through solids
Example: Heating marshmallows with a metal rod, as
the marshmallow cook, the wire you are holding is
getting hotter.
23
24. The transfer of energy by the
movement of fluid with different
temperature
During convection, energy is carried
away by a heated gas or liquids that
expand and rises above cooler,
denser gas or liquid
Energy transfer through gases and
liquids (both fluids)
The cycle of a heated fluid that rises
and then cools and fall is called
convection current
24
25. The transfer of energy by electromagnetic waves
Energy transfer that does not need any material
to transfer to, it travels in waves
Example:You stand near the heat of the fire and
feel the heat, energy is transferred as eat from
the fire in this case in the form of
electromagnetic waves
Radiation differs from conduction and
convection in that it does not involve the
movement of matter
25
26. The law of conservation of energy: energy cannot be
created or destroyed. It can only be transferred from
one form to another.
Heat is the transfer of energy from the particles of
one object to those of another object due to
temperature difference between the two objects.
Also remember that, transfer of energy always takes
place from a substance at a higher temperature to a
substance at a lower temperature
Three methods of energy transfer: conduction,
convection and radiation 26
28. Thermochemical Equations
28
C.11.C use thermochemical equations to calculate
energy changes that occur in chemical reactions and
classify reactions as exothermic or endothermic
29. Thermochemical Equations
A Thermochemical Equation is a balanced
stoichiometric chemical equation that includes
the enthalpy change, ΔH.
Enthalpy (H) is the transfer of energy in a
reaction (for chemical reactions it is in the form
of heat) and ΔH is the change in enthalpy.
By definition, ΔH = Hproducts – Hreactants
Hproducts < Hreactants, ΔH is negative
Hproducts > Hreactants, ΔH is positive
29
30. Thermochemical Equations
In working with thermochemical equations you
will find the following rules helpful.
When a thermochemical equation is multiplied
by a factor, the value of H for the new equation
is obtained by multiplying the value of H by the
same factor.
When a chemical equation is reversed, the sign
of H is reversed.
30
31. Writing Thermochemical Equations
Thermochemical equations show the exchange
of heat in a chemical reaction.
For example, Burning one mole of wax
releases 20,000 kJ of heat energy.
This could be written as:
C40H82 + 60.5 O2 → 40 CO2 + 41 H2O + 20,000 kJ
Instead we usually write:
C40H82 + 60.5 O2 → 40 CO2 + 41 H2O ΔH = -20,000
kJ
31
32. Practice
Write the following thermochemical equations showing
∆H.▫ Reacting 2 moles of solid sodium with 2 moles of
water to produce 2 mole of aqueous sodium
hydroxide and 1 mole of hydrogen gas will release
367 kJ of energy
▫ 184.6 kJ of energy is needed to produce 1 mole of
hydrogen gas and 1 mole of chlorine gas from 2
moles of hydrogen chloride gas.
▫ 2Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2 (g) + 367 kJ
or
▫ 2Na (s) + 2 H2O (l) → 2 NaOH (aq) + H2 (g) ∆H=- 367
kJ
▫ 2 HCl (g) + 184.6 kJ → H2 (g) + Cl2 (g) or
▫ 2 HCl (g) → H2 (g) + Cl2 (g) ∆H= + 184.6 kJ
32
33. Thermochemical equations using
Standard Heat of Formations
C2H2(g) + 2 H2(g) → C2H6(g)
Information about the substances involved in
the reaction represented above is summarized
in the following tables.
Write the equation for the heat of formation of
C2H6(g)
Substance DH°f
(kJ/mol)
C2H2(g) 226.7
C2H6(g) -84.7
33
34. Thermochemical equations using
Standard Heat of Formations
• Write the equation for the heat of
formation of C2H6(g)
Substance DH°f
(kJ/mol)
C2H2(g) 226.7
C2H6(g) -84.7▫ 1st: Using our balanced chemical
equation, we see how many moles of each compound we
have.
C2H2(g) + 2 H2(g) → C2H6(g) [(H2) does not have a DH°f ]
1 mol of C2H2(g) and 1 mol C2H6(g)
▫ 3rd: We solve for ∆H°
∆H° = [-84.7] – [226.7] = -331.4 kJ/mol
▫ 2nd: We plug in the ∆H°f for each of our compounds,
remembering that
∆H° = [∆H°f products] – [∆H°f reactants]
∆H° = [C2H6(g)] – [C2H2(g)] =
34
35. Practice Problems
Solve for the ΔHrx and write the
following thermochemical equations.
1. What is the ΔHrx for the process
used to make lime (CaO)?
CaCO3(s) → CaO(s) + CO2(g)
Substance DH°f
(kJ/mol)
CaCO3(s) -1207.6
CaO(s) -634.9
C 4H10 (g) -30.0
H2O (g) -241.82
CO2 (g) -393.5
▫ 2. What is the ΔHrx for the combustion of C4H10(g)?
2 C4H10 (g) + 13 O2 (g) → 10 H2O (g) + 8 CO2 (g)
35
36. Practice Problems
Solve for the ΔHrx and write the
following thermochemical equations.
1. What is the ΔHrx for the process used
to make lime (CaO)?
CaCO3(s) → CaO(s) + CO2(g)
Substance DH°f
(kJ/mol)
CaCO3(s) -1207.6
CaO(s) -634.9
C 4H10 (g) -30.0
H2O (g) -241.82
CO2 (g) -393.5
36
ΔHrx = [ΔH°f (CaO) + ΔH°f (CO2)] – [ΔH°f (CaCO3)]
ΔHrx = [(-634.9)+(-393.5)] – [(-1207.6)]
ΔHrx = [ -1028.4] – [-1207.6] = +179.2 kJ
CaCO3(s) → CaO(s) + CO2(g) ΔHrx = 179.2
kJ/mol
37. Practice Problems
Solve for the ΔHrx and write the
following thermochemical equations.
Substance DH°f
(kJ/mol)
CaCO3(s) -1207.6
CaO(s) -634.9
C 4H10 (g) -30.0
H2O (g) -241.82
CO2 (g) -393.5
37
2. What is the ΔHrx for the
combustion of C4H10(g)?
2 C4H10 (g) + 13 O2 (g) → 10 H2O (g) + 8 CO2 (g)
ΔHrx = [ΔH°f (H2O) + ΔH°f (CO2)] – [ΔH°f (C4H10)]
(We do not include O2 because its ΔH°f is 0.)
ΔHrx = [10(-241.82)+8(-393.5)] – [2(-30.0)]
ΔHrx = [ -5566.2] – [-60.0] = -5506.2 kJ
2 C4H10 (g) + 13 O2 (g) → 10 H2O (g) + 8 CO2 (g) ΔHrx = -5506.2
kJ/mol
38. Thermochemical & Endothermic/
Exothermic equations
In the previous slides, we saw how ΔH° could be both
positive or negative.
Depending on the sign of ΔH°, the reaction can either
be exothermic or endothermic.
Exothermic reactions release heat from the system
to the surroundings so the temperature will rise.
ΔH° will be negative because the reaction loses heat.
ΔH° can be written into the chemical equation as a
product.
Endothermic reactions absorb heat from the
surroundings into the system so the temperature will
decrease.
ΔH° will be positive because the reaction absorbs heat.
ΔH° can be written into the chemical equation as a
reactant.
38
39. Classify the following as endothermic
or exothermic
Ice melting
2 C4H10(g) + 13 O2(g) → 10 H2O(g) + 8 CO2(g) ΔHrx = -5506.2
kJ/mol
2 HCl (g) + 184.6 kJ → H2 (g) + Cl2 (g)
Water vapor condensing
39
40. Exothermic vs. Endothermic
EXOTHERMIC ENDOTHERMIC
A change in a chemical
energy where
energy/heat EXITS the
chemical system
Results in a decrease in
chemical potential
energy
ΔH is negative
A change in chemical
energy where
energy/heat ENTERS the
chemical system
Results in an increase in
chemical potential
energy
ΔH is positive
40
42. Specific Heat: The Equation
42
C.11.D perform calculations involving heat, mass,
temperature change, and specific heat
43. Temperature and Energy
43
We relate energy and temperature by discussing a
substance’s heat capacity.
Heat Capacity = heat required to raise temp. of an object by
1oC
more heat is required to raise the temp. of a large sample of a
substance by 1oC than is needed for a smaller sample
Specific Heat Capacity
a physical property of matter that describes matter’s resistance
to a change in temperature. The symbol for specific heat is Cp.
Not all substances heat up at the same rate. Some get hot quickly
and some more slowly.
44. Example
44
If you have ever touched the
metal on a car and the fabric on
the car seat on a hot day, you
have experienced the affect of
specific heat. The metal seems
much hotter than the fabric
seat even if after receiving the
same amount of energy from
the sun. This is caused by the
difference in the specific heat of
each of the materials. The
metal has a lower specific heat
and gives up its thermal energy
at a much higher rate than does
the fabric which has a much
higher specific heat.
45. High Specific Heat and Water
45
Water has a very high specific heat compared to
other matter; therefore ocean water stays about the
same temperature throughout day and night despite
the differences in temperature between night and
day. That also explains why water is used in car
radiators to cool the engine.
Low specific heat = less energy required to change the
temperature
High specific heat = more energy required to change the
temperature
46. Practice
46
Which would get hotter if left in the sun?
Penny vs. Water
Keys vs. soccer ball
Plastic recycling bin vs. metal trash can
47. Specific Heat Capacity
47
Temperature change of a substance depends on three
things:
Mass, m
Amount of energy added, Q
Specific Heat, Cp
Final
temperature
Initial
temperature
Temperature
change
49. Using Q = m x Cp x (Tf – Ti)
49
The following problems will show you how to solve for
different variables in our equation.
How much energy does it take to raise the
temperature of 50 g of aluminum (cp = 0.9025
J/gC0) by 10 0C?
Q = (50g) (0.9025 J/gC0) (100C)
Q = (m) (cp) (Tf - Ti)
Q = 451.25 Joules
50. Using Q = m x Cp x (Tf – Ti)
50
If we add 30 J of heat to lead (cp = 0.1276J/gC0)
with a mass of 10 g, how much will its temperature
increase?
Q = (m) (cp) (Tf - Ti)
30J = (10g) (0.1276 J/gC0) (x)
30J = (1.276 J/0C) (x)
23.50C = x = temperature increase
53. Calorimetry
• Calorimetry is the science of measuring the
heat of chemical reactions or physical
changes.
▫ Calorimetry is also known as a laboratory procedure
that measures the amount of heat transferred to the
surroundings by a reaction.
Calorimetry can be calculated when heat of
combustion is given and the mass of the substance is
known or,
During a calorimetry procedure, the heat released
during a chemical or physical change is transferred to
another substance, such as water, which undergoes a
temperature change.
53
54. Calorimetry Calculations
• Example 1: Propane is a commonly used fuel. 1
mol of C3H8 releases 2,220 kJ of heat during
combustion. The molar mass of C3H8 is 44.1
g/mol. How much heat is released if a firework
contains 67.8 g of C3H8?
54
2nd use the heat of combustion of propane to calculate energy
(heat) released
1.53 mol C3H8 x 2,220 kJ = 3413.06 kJ => 3410 kJ released
1 mol
1st convert the grams of C3H8 to moles of C3H8.
67.8 g C3H8 x 1 mol C3H8 = 1.53 mol C3H8
44.1 g C3H8
55. Calorimetry Calculations
• The temperature change, fuel mass, and water
volume data from a calorimetry procedure can
be used to determine how much heat is
transferred during a combustion reaction.
▫ The amount of energy transferred from a substance
during combustion depends on the identity and mass of
the substance.
▫ The equation can be seen as q1 = - q2. One will be losing
energy, the other will be gaining energy.
55
56. Calorimetry Calculations
• Example 2: 175 grams of hot aluminum (100.°C) is
dropped into an insulated cup that contains 40.0
mL of ice cold water (0.0°C). Follow the example
above to determine the final temperature, x.
56
1st set up expressions for energy released and energy absorbed.
Q = - (175 g) (0.900 J/g●
◦C) (x -100 ◦C) for silver and Q = (40.0 g) (4.184
J/g●◦C) (x -0.0 ◦C) for cold water
2nd put expressions together.
- (175 g) (0.900 J/g●
◦C) (x -100 ◦C) = (40.0 g) (4.184 J/g●
◦C) (x -0.0 ◦C)
3rd solve for x.
- 157.5 (x – 100) = 167.4 (x - 0.0)
- 157.5 x + 1575 = 167.4 x
1575 = 324.9 x => x = 48.5 ◦C