11/8/2011
Ideal and not-so-Ideal Gases
Boyle (UK)-1662 & Mariotte (FR)-1676
Ideal Gas Law: P V = RT
Amontons-1702
Absolute Zero—
Temperature at which
Pressure goes to zero
at fixed Volume
Amontons
Also proposed Theory of
Friction
Celsius Scale-1742
• On Fahrenheit scale, two • Why not, Celsius
very significant things
thought, simplify
for humans happened at
things a bit and call
two very insignificant
the freezing point zero
points. The temperature
and the boiling point
at which water freezes is
100.
at 32 degrees and the
temperature at which
water boils is at 212.
• Why did Mr. F. do this?
Thermometry
• Daniel Gabriel Fahrenheit
(1686-1736)
• German physicist
• invented alcohol
thermometer (1709)
• Hg thermometer in (1714)
• Introduced temperature
scale - Fahrenheit Scale-in
1724.
Johann Lambert-1779
• In 1779 Joseph Lambert proposed a definition for absolute
zero on the temperature scale that was based on the straightline relationship between the temperature and pressure of a
gas.
What is the difference between this and
what Amontons conjectured in 1702?
Anders Celsius
William Thomson Kelvin-1848
KELVIN, Lord (William Thomson)
(1824 - 1907)
• Proposed an absolute
scale of temperature in
1848.
• The absolute scale that
he proposed was based
on his studies of the
theory of heat, in
particular the theory
proposed by Sadi
Carnot
It was Thomson's studies in thermodynamics though which led him to
propose his absolute scale of temperature in 1848.
Kelvin is an absolute scale in that temperatures below 0K (absolute zero)
do not exist anywhere in the universe. Equivalent to -273.15° Celsius or 459.67° Fahrenheit, 0K is the temperature at which molecular energy is a
minimum i.e. all molecular motion would cease.
He developed it by 'extrapolating' backwards on volume-temperature and
pressure-temperature graphs. He discovered that the temperature axis
was cut at -273°C. Kelvin was also aided in the developing of his
scale by a 'carnot engine'. Kelvin defined his thermodynamic scale so
that a Kelvin was exactly the same as one degree Celsius.
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11/8/2011
Rankine, William (1820-1872)
• Invented an absolute
temperature based on the
interval of one degree
Fahrenheit termed the
Rankine temperature scale.
• 1850 – “Mechanical Action of
Heat.” –formulated heat
theory.
1852
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