Chapter-6-KW - Chapter 6 Energy and Chemical Change Index...

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Chapter 6 Energy and Chemical Change
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Index 6.1 An object has energy if it is capable of doing work 6.2 Internal energy is the total energy of an object’s molecules 6.3 Heat can be determined by measuring temperature changes 6.4 Energy is absorbed or released during most chemical reactions 6.5 Heats of reaction are measured at constant volume or constant pressure 6.6 Thermochemical equations are chemical equations that quantitatively include heat 6.7 Thermochemical equations can be combined because enthalpy is a state function 6.8 Tabulated standard heats of reaction can be used to predict any heat of reaction using Hess’s law
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6.1 An object has energy if it is capable of doing work 3 Energy is the Ability to do Work Energy is the ability to do work (move mass over a distance) or transfer heat Types: kinetic and potential § Kinetic - the energy of motion § Potential - the stored energy in matter Internal energy (E) - the sum of the kinetic and potential energy for each particle in the system
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6.1 An object has energy if it is capable of doing work 4 Kinetic Energy: The Energy of Motion KE = ½ mv 2 Energy can be transferred by moving particles Collision of fast particles with slower particles causes the slow particle to speed up while the fast molecule slows § This is why hot water cools in contact with cool air
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6.1 An object has energy if it is capable of doing work 5 Potential Energy Depends on Position Potential energy increases when: § Objects that attract move apart, or § Objects that repel move toward each other Stored energy that can be converted to kinetic energy
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6.1 An object has energy if it is capable of doing work 6 Law of Conservation of Energy Energy cannot be created or destroyed, but can be transformed from one form of energy to another Also known as the first law of thermodynamics How does water falling over a waterfall demonstrate this law?
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6.1 An object has energy if it is capable of doing work 7 Heat and Temperature are Not the Same The temperature of an object is proportional to the average kinetic energy of its particles—the higher the average kinetic energy, the higher the temperature Heat is energy (also called thermal energy ) transferred between objects caused by differences in their temperatures until they reach thermal equilibrium
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6.2 Internal energy is the total energy of an object’s molecules 8 Temperature ( T ) is proportional to the average kinetic energy of all particle units: °C, °F, K § KEaverage= ½ mv average2 At a high temperature, most molecules are moving at higher average What is Temperature?
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6.1 An object has energy if it is capable of doing work 9 Units of Energy SI unit is the Joule, J § J = kg·m/s2 § If the calculated value is greater than 1000 J, use the kJ Another unit is the calorie, cal § cal = 4.184 J (exact) Nutritional unit is the Calorie (note capital C), which is one kilocalorie § 1 Cal = 1 kcal = 4.184 kJ
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6.2 Internal energy is the total energy of an object’s molecules 10
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This note was uploaded on 01/24/2012 for the course CHEMISTRY 211 taught by Professor Crowley during the Fall '08 term at Wichita State.

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Chapter-6-KW - Chapter 6 Energy and Chemical Change Index...

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