12 & 13 & 14
the melting point the atoms of a crystalline substance are moving
so vigorously that any additional energy goes into breaking the
intermolecular bonds that hold the solid together. The internal
energy of the system increases, although the temperature remains
constant throughout the melting process.
amount of heat that must be added to a kilogram of any solid
at its melting temperature in order to liquefy is the latent
heat of fusion. (J/kg)
water the heat of fusion is .
change the phase of a mass already at its melting point requires
the addition of an amount of heat:
a liquid or solid into a gas.
amount of heat that must be added to a kilogram of any liquid
to evaporate it is the heat of vaporization.
water the heat of vaporization is .
change the phase of a mass already at its vaporization point
requires the addition of an amount of heat:
of Thermal Energy
radiation is characterized by a broad, continuous range of wavelengths,
which arises from interactions among the atoms of solids, liquids,
and dense gases.
amount of thermal radiation emitted by a body depends on its
surface condition (color, texture, exposed area, etc.) and on
amount of thermal radiation absorbed by a body depends on its
surface condition and on the nature of the incident radiant energy
(wavelength, intensity, etc.) which, in turn, depends on the
temperature of the source.
a region of fluid is heated and its density decreases so that
it rises. The colder fluid around sinks and a current is set
is only conducted only from high to a low temperature. The measure
of the ability of a substance to transmit heat is known as its
thermal conductivity ().
This constant depends on the atomic structure of the material.
to the First Law of Thermodynamics