CH110-120 Chapter 3 Lecture Notes

# CH110-120 Chapter 3 Lecture Notes - Chapter 3 Energy and...

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Chapter 3 – Energy and its Conservation 3.1 Types of Energy 3.2 Thermodynamics 3.3 Energy Changes in Chemical Reactions 3.4 Measuring Energy Changes: Calorimetry 3.5 Enthalpy 3.6 Energy Sources

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3.1 Types of Energy Energy – the ability to do work has a unit of Joules 1. Kinetic Energy 2. Potential Energy: a. Electrical b. Chemical c. Mass 3. Thermal Energy 4. Radiant Energy Energy – the ability to do work has a unit of Joules 1. Kinetic Energy 2. Potential Energy: a. Electrical b. Chemical c. Mass 3. Thermal Energy 4. Radiant Energy W = Fd force and displacement Unit of force: Neutons 1N = 1kg.m/s 2 Displacement Unit = m W = kg m 2 /s 2 = mv 2
Kinetic Energy Every moving object has kinetic energy because it results from the movement of objects. It is dependent on the velocity (v) and mass (m) of an object. Joule (J): the SI unit of energy 2 kinetic 1 E mv 2 = 2 2 s m kg 1 J 1 joule 1 = =

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Potential Energy Electrical Energy - energy from positive and negative ions held a small distance apart q 1 and q 2 are the charges of two ions, r is the distance between the ions in pm k =2.31 x 10 -16 J pm 1 2 electrical q q E = k r picometres
Potential Energy Chemical Energy: energy resulting from attraction of the electrons and nuclei in molecules (bond energy) Mass: transformation of mass into energy ( E = mc 2 ) H-H The electron in one atom is attracted to the nucleus of the other atom Nuclear process

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Thermal and Radiant Energy Thermal Energy : the total energy of random movements of molecules Radiant Energy : energy as a result of electromagnetic radiation. Energy constant of a hot object (heat) movement of molecules: 1.Vibrational 2.Rotational 3.Translational: basically an object moving (for a gas, E kin = 3RT/2N A ) light
Energy Transfer and Transformations Energy can be transferred from one type to another. Energy transformations accompany chemical reactions.

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3.2 Thermodynamics The study of energy transfers and transformations “how much energy goes where” Terms: System : whatever we want to describe and study by itself. Surroundings : everything else but the system Boundary : - what separates the system from its surroundings
Conservation of Energy Energy is neither created nor destroyed in any process, although it may be transferred from one body to another or transformed from one form into another OR RESTATED Energy may be transferred as work or heat, but no energy can be lost, nor can heat or work be obtained from nothing.

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Heat Thermal energy that is exchanged with its surroundings is referred to as heat (q). It is measured in units of joules (J). Heat flow is associated with a change in temperature (ΔT)
Heat Flows and Temperature 1. ∆ T depends on q, the amount of heat transferred. 2. ∆

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## This note was uploaded on 10/14/2011 for the course CHEM 110 taught by Professor Maly during the Fall '10 term at Wilfred Laurier University .

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CH110-120 Chapter 3 Lecture Notes - Chapter 3 Energy and...

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