Thermochemistry
2013/07/09
Lecture Presentation
Chapter 5 Thermochemistry
John D. Bookstaver St. Charles Community College Cottleville, MO
© 2012 Pearson Education, Inc.
Energy
• Energy is the ability to do work or transfer heat.
– Energy used to cause an object that has mass to move is called work. – Energy used to cause the temperature of an object to rise is called heat.
Thermochemistry © 2012 Pearson Education, Inc.
1
2013/07/09
Kinetic Energy
Kinetic energy is energy an object possesses by virtue of its motion: 1 Ek = mv2 2
Thermochemistry © 2012 Pearson Education, Inc.
Potential Energy
• Potential energy is energy an object possesses by virtue of its position or chemical composition. • The most important form of potential energy in molecules is electrostatic potential energy, Eel: KQ1Q2 Eel = d
Thermochemistry © 2012 Pearson Education, Inc.
2
2013/07/09
Units of Energy
• The SI unit of energy is the joule (J): kg m2 1 J = 1 s2 • An older, non-SI unit is still in widespread use: the calorie (cal): 1 cal = 4.184 J
Thermochemistry © 2012 Pearson Education, Inc.
Definitions: System and Surroundings
• The system includes the molecules we want to study (here, the hydrogen and oxygen molecules). • The surroundings are everything else (here, the cylinder and piston).
Thermochemistry © 2012 Pearson Education, Inc.
3
2013/07/09
Definitions: Work
• Energy used to move an object over some distance is work: • w=Fd where w is work, F is the force, and d is the distance over which the force is exerted.
Thermochemistry © 2012 Pearson Education, Inc.
Heat
• Energy can also be transferred as heat. • Heat flows from warmer objects to cooler objects.
Thermochemistry © 2012 Pearson Education, Inc.
4
2013/07/09
Conversion of Energy
• Energy can be converted from one type to another. • For example, the cyclist in Figure 5.2 has potential energy as she sits on top of the hill.
Thermochemistry © 2012
Lecture Presentation
Chapter 5 Thermochemistry
John D. Bookstaver St. Charles Community College Cottleville, MO
© 2012 Pearson Education, Inc.
Energy
• Energy is the ability to do work or transfer heat.
– Energy used to cause an object that has mass to move is called work. – Energy used to cause the temperature of an object to rise is called heat.
Thermochemistry © 2012 Pearson Education, Inc.
1
2013/07/09
Kinetic Energy
Kinetic energy is energy an object possesses by virtue of its motion: 1 Ek = mv2 2
Thermochemistry © 2012 Pearson Education, Inc.
Potential Energy
• Potential energy is energy an object possesses by virtue of its position or chemical composition. • The most important form of potential energy in molecules is electrostatic potential energy, Eel: KQ1Q2 Eel = d
Thermochemistry © 2012 Pearson Education, Inc.
2
2013/07/09
Units of Energy
• The SI unit of energy is the joule (J): kg m2 1 J = 1 s2 • An older, non-SI unit is still in widespread use: the calorie (cal): 1 cal = 4.184 J
Thermochemistry © 2012 Pearson Education, Inc.
Definitions: System and Surroundings
• The system includes the molecules we want to study (here, the hydrogen and oxygen molecules). • The surroundings are everything else (here, the cylinder and piston).
Thermochemistry © 2012 Pearson Education, Inc.
3
2013/07/09
Definitions: Work
• Energy used to move an object over some distance is work: • w=Fd where w is work, F is the force, and d is the distance over which the force is exerted.
Thermochemistry © 2012 Pearson Education, Inc.
Heat
• Energy can also be transferred as heat. • Heat flows from warmer objects to cooler objects.
Thermochemistry © 2012 Pearson Education, Inc.
4
2013/07/09
Conversion of Energy
• Energy can be converted from one type to another. • For example, the cyclist in Figure 5.2 has potential energy as she sits on top of the hill.
Thermochemistry © 2012