BLBCJM-CH5-07

# BLBCJM-CH5-07 - Thermochemistry Chapter 5 P4 Due of Week of...

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Thermochemistry Chapter 5 P4 Due of Week of 10/8; 5.14, 5.33, 5.38, 5.54, 5.61 5.64, 5.70, 5.73, 5.77, 5.82

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Energy is the capacity to do work Thermal energy is the energy associated with the random motion of atoms and molecules Chemical energy is the energy stored within the bonds of chemical substances Nuclear energy is the energy stored within the collection of neutrons and protons in the atom Electrical energy is the energy associated with the flow of electrons
Kinetic Energy and Potential Energy Kinetic energy is the energy of motion: Potential energy is the energy an object possesses by virtue of its position. Potential energy can be converted into kinetic energy. Example: a bicyclist at the top of a hill . The Nature of Energy The Nature of Energy 2 2 1 mv E k =

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• Electrostatic potential energy, E d , is the attraction between two oppositely charged particles, Q 1 and Q 2 , a distance d apart: The constant κ = 8.99 × 10 9 J-m/C 2 . • If the two particles are of opposite charge, then E d is the electrostatic repulsion between them. d Q Q E d 2 1 κ = Kinetic Energy and Potential Energy
SI Unit for energy is the joule, J: A calorie instead of the joule: 1 cal = 4.184 J (exactly) A nutritional Calorie: 1 Cal = 1000 cal = 1 kcal ( 29 ( 29 J 1 m/s - kg 1 m/s 1 kg 2 2 1 2 1 2 2 2 = = = = mv E k Units of Energy

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Kinetic Energy The energy associated with an object by virtue of its motion. E k = 1/2mv 2 For example, if a person whose mass is 59 kg and speed is 26.8 m/s their kinetic energy is…. E k = ½(59 kg)(26.8m/s) 2 = 2.12x10 4 kg.m 2 /s 2 The SI unit of energy kg.m 2 /s 2 is given the name Joule (English physicist James Prescott Joule) Thus answer is 2.12x10 4 J or 21.2 kJ.
Potential Energy is the energy an object has by virtue of its position in a field of force. Potential energy is in essence stored energy. Example: water behind a dam, the potential energy of the water at the top of the dam is converted to kinetic energy when the water falls.

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Exercise 5.1; What is the kinetic energy in J of A) an Ar atom moving with a speed of 650 m/s, B) a mole of Ar atoms moving with a speed of 650 m/m? (Hint: 1 amu = 1.66x10 -27 kg) E k = 1/2mv 2 E k = 39.948 amu (1.66x10 -27 kg/1 amu)(650 m/s) 2 E k = 1.4x10 -20 kg m 2 /s 2 or J E k = 1.4x10 -20 J x 6.02x10 23 atoms/mole E k = 8.4x10 3 J
Systems and Surroundings System: part of the universe we are interested in. Surroundings: the rest of the universe.

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Thermochemistry is the study of heat change in chemical reactions. The system is the specific part of the universe that is of interest in the study. open Exchange: closed energy isolated nothing
Force is a push or pull on an object. Work is the product of force applied to an object over a

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## This note was uploaded on 08/17/2008 for the course CHE 101 taught by Professor Churchhill during the Spring '08 term at SUNY Buffalo.

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BLBCJM-CH5-07 - Thermochemistry Chapter 5 P4 Due of Week of...

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