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# Energy in Thermal Processes PowerPoint PPT Presentation

Energy in Thermal Processes. Heat Calorimetry Phase Changes. 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

Energy in Thermal Processes

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## Energy in Thermal Processes

Heat

Calorimetry

Phase Changes

### 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 ΔT

### Units of Heat

• Historically defined in terms of __________ _________ of object

• calorie (cal) – the energy necessary to raise the temperature of 1g of water from 14.5°C to 15.5°C

• British thermal unit (BTU) – the energy necessary to raise the temperature of 1 lb of water from 63°F to 64°F

• Heat (like work) is a transfer of energy and has SI units of ________

### Specific Heat

• Every substance requires a ________ amount of energy per unit mass to change T by 1°C

• Characterize the material by its _______ heat c

• Units are J/(kg∙°C)

• See Table 11.1, p. 355

### 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

### 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

### Example: Ice to Steam

Fig. 11.3, p. 361