Energy in Thermal Processes

1
Energy in Thermal Processes

• Heat
• Calorimetry
• Phase Changes

2
Heat and Internal Energy

• _______ _______, U, is energy of atoms and
  molecules of a system
• Includes KE of translation, rotation, vibration
• Includes PE of chemical/electrical bonds
• ______, Q, is transfer of energy between system
  and environment due to temperature difference ?T

3
Units of Heat

• Historically defined in terms of __________
  _________ of object
• calorie (cal) the energy necessary to raise the
  temperature of 1g of water from 14.5C to 15.5C
• British thermal unit (BTU) the energy necessary
  to raise the temperature of 1 lb of water from
  63F to 64F
• Heat (like work) is a transfer of energy and has
  SI units of ________

4
Specific Heat

• Every substance requires a ________ amount of
  energy per unit mass to change T by 1C
• Characterize the material by its _______ heat c
• Units are J/(kgC)
• See Table 11.1, p. 355

5
Calorimetry

• Use containers that are good ________ (no energy
  leaves/enters the container)
• Put warmer and cooler materials in container
• Apply conservation of ______

In general
Sign of ____ takes care of sign of Q
6
Latent Heat and Phase Change

• Sometimes energy transfer results in changes of
  ____ (melting/freezing _____,
  boiling/condensing _________)
• _____________ does not change
• Characterized by latent heat L
• See Table 11.2, p. 360 units are J/kg

Use if ______ energy, sign if _______ energy
7
Example Ice to Steam
Fig. 11.3, p. 361