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