SCI 2201: Concepts in Science
Discussion Topic: Heat and Thermodynamics Trefil and Hazen The Sciences Chapter 4
This discussion should help you to:
1.
2.
3.
4.
5.
6.
distinguish between heat and temperature
compare and contrast the Fahrenheit, Celsius, and Kelvin temperature scales
explain the meaning of the term “absolute zero”
explain thermal expansion and specific heat capacity.
relate the kinetic energy of particles (atoms, molecules) to the phases of matter.
interpret energy changes in various phase change events (melt, freeze,
evaporation, sublimation, condensation, boiling).
7. compare and contrast the three methods in which heat can be transferred from one
object to another.
8. discuss the second law of thermodynamics, and relate the tendency toward
entropy to energy transformations.
Science Literacy Benchmarks
(AAAS, 1993, 4.E: Energy Transformations)
By the end of the 12th grade, students should know that
 Heat energy in a material consists of the disordered motions of its atoms or
molecules. In any interactions of atoms or molecules, the statistical odds are that
they will end up with less order than they began—that is, with the heat energy
spread out more evenly. With huge numbers of atoms and molecules, the greater
disorder is almost certain.
 Transformations of energy usually produce some energy in the form of heat,
which spreads around by radiation or conduction into cooler places. Although just
as much total energy remains, its being spread out more evenly means less can be
done with it.
By the end of the 8th grade, students should know that
 Heat can be transferred through materials by the collisions of atoms or across
space by radiation. If the material is fluid, currents will be set up in it that aid the
transfer of heat.
By the end of the 5th grade, students should know that
 When warmer things are put with cooler ones, the warm ones lose heat and the
cool ones gain it until they are all at the same temperature. A warmer object can
warm a cooler one by contact or at a distance.
 Some materials conduct heat much better than others. Poor conductors can reduce
heat loss.
By the end of the 2nd grade, students should know that:
 The sun warms the land, air, and water.
SCI 2201 Chapter 4 Quiz
Formulas:
o
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F = (1.8 x oC) + 32
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C = (oF – 32) / 1.8
o
1. What is the difference between “heat” and “temperature”? Why is it
important to teach children the difference? (3 points) Heat is a form of energy
that moves from a warmer object to a cooler object; heat is thus energy in motion. A
gallon of boiling water contains more internal energy than a pint of boiling water, and it
can thus transfer more heat. Temperature is a relative term that measures the kinetic
energy or molecular motion of atoms. Answers will vary for the relevance of this topic
for the science literacy of our students, but should reflect the difference between the form
of energy and its measure.
2. You’ve just landed in Lisbon, Portugal and hear the steward announce the
weather conditions: “Partly cloudy skies, 34 degrees Celsius, with a 40
percent chance of precipitation.”
a. (1 point) What is the temperature in degrees Fahrenheit?
1.8 (34C) + 32 = 61.2 oF
b. (2 points) Why does the C  F conversion formula include the
numbers 1.8 and 32?
1.8 represents the fact that the English scale has 1.8 times the units of the metric
scale, both of which are based on the freezing and boiling points of water (0-100
degrees Celsius vs 32-212 degrees Fahrenheit).
32 is added since the freezing point of water on the English scale is this number of
units above that of the metric scale.
3. (2 points)
a. With regard to heat, explain the meaning of the term “absolute zero”.
This is the lower limit to temperature, -273 C or –459 F. Absolute zero is the point at
which molecules lose all kinetic energy, and have no motion at all.
b. Temperatures of approximately 0.000001 K have been reached, but
“absolute zero” has never been achieved. Why do we think “absolute
zero” exists?
For gases at constant pressure, each 1oC drop in temp reduces volume by 1/273. If a
gas at 0oC were cooled to –273oC, it would contract down to a volume of zero.
Technically, absolute zero has not been realized, but let’s face it, that fact that we’ve
reached 0.000001 K or one millionth of a Kelvin is quite strong evidence for absolute
zero temperature.
4. Interpret this graph. (2 points)
The upward trend in the graph of water’s temperature measured while heat is
delivered over time of water indicates the following:
--temperature is increasing as the liquid is heated, increasing it’s molecular motion
--temperature is not increasing (as indicated by plateau phases on the graph) because
the heat delivered is not increasing molecular motion, but is doing the work of either
melting ice (prior to liquid phase) or boiling water (prior to complete conversion to
steam).