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Books: H. C. Van Ness, "Understanding Thermodynamics" H. C. Von Baeyer, "Why Warmth Disperses and Time Passes" Photocopies are available at Copy Central (opposite North Gate of campus)  for ~ $15 for the two.

Reference Texts: (on reserve in Engineering Library)Van Wylen, Sonntag, and Borgnakke, “Fundamentals of Classical Thermodynamics”, 4th Ed., Wiley (1994)

Gaskell, “Introduction to Metallurgical Thermodynamics”, 2nd Ed., McGraw-Hill (1981);

Assignment #1: Read Von Baeyer; solve problem on slide 6 Quiz 9/5 AM (closed book) will cover V-B and lecture on History of Thermo

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A Brief History of Thermodynamics

• The driving force for the development of thermodynamics was the invention of the steam engine at about 1700

• From 1700 to 1900, thermodynamic theory was slowly and painfully developed

• By 1900, “classical” thermodynamics was essentially complete

• In time, various special branches of thermodynamics developed

8/28/07

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The Concept of Temperature

•Lavoisier (1780) realized that matter is composed of discrete atoms and molecules

• Dalton (1808), temperature interpreted as a measure of particle speed (gas) or vibration (solid)

•Without realizing its significance, Galileo (ca 1630) developed a crude thermometer

•Fahrenheit (1715); measured temperature by expansion of a fluid (mercury)•Celsius (1742) defined 0oC as the melting point of ice; 100oC as the boiling point of water; with a scale in between linear with expansion of fluid – why?

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•Kelvin (ca 1885) introduced the notion of the absolute zero temperature, where all atomic motion stops: T(K) = T(oC ) + T0; absolute zero is 0 K or -T0

oC . How to determine T0 ?

Boiling waterX

SolidCO2

x

-273=T0

Icex

T,oC

pgas0

0

Absolute zero = - 273 oC

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Gas Thermometer

Heater

Relief valve

~ 1.6 m

FlaskVol = VF

Oil

•Air in the flask expands with temperature and exerts pressure on the surface of the oil, causing it to rise in the column. • with ice in the air flask: TF = 0 + 273 = 273 K

- Relief valve open - po = 1 atm

- moles gas =

To = 22 + 273 = 295 K

ColumnArea = AC

Reservoir

otFFo T/VT/V)R/p(

Tubing, vol = Vt

n1

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• Relief value closed & ice removed –

air flask at room temperature (22 oC)• oil rises to height

h1

pC

p1

h1

Initialoil level

• repeat for flask at T = 100oC

Homework problem! solve for h1

oil = 0.84 g/cm3 g = 9.8 m/s2

Volumes:

- Air flask 500 cm3

- Tubing from air flask to

oil flask: 2 cm3

- Oil flask neck inside diam. = 3 cm

- Column inside diameter 0.95 cm

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Finally, the temperature scales are fixed:

• International Committee (1954): defines the unique state of water: the triple point

• where ice, water, and water vapor (only) coexist at 0.01oC and 611 Pa (0.00611 atm)

• The triple-point temperature anchors the temperature scale

• Does not affect absolute zero (-273.15oC)

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Heat• Since the 18th Cent., heat was viewed as a “fluid” (caloric)

that moves from a body at high temperature to one at low temperature

• During the 19th Cent., the correct view of heat was uncovered:

-increasing the temp.of a body

- melting a body- vaporizing a liquid

- producing mechanical work

Heat is energy in motion from a hot system to cold surroundings (or vice versa)

• Some effects of heat :

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Work• Known from mechanics since Newton (1687) as

force x distance.

• Heat and Work are two aspects of energy in motion; work is completely convertible to heat (Rumford, Joule (1840))but not vice versa! (e.g., steam engine)

• Forms of Work:- expansion/contraction: like a balloon- rotating equipment: steam or gas turbine- electrical work: electric cars- mechanical: moving levers, lifting weights, etc.

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Count Rumford’s canon-boring experiment (1797)

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- heat in calories (to raise the temp. of 1 gram of water 1oC) - work in Joules (force of 1 Newton over 1 m)

4.184 Joules per calorie • With energy, heat and work in the same units the 1st law was ready to be established

Joule (ca 1850) – the first thermodynamic experimentalist measured:

The Mechanical Equivalent of Heat

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But what is energy?We have no knowledge of what energy is …it is an abstract thing… (Richard Feynman)

• Energy comes in many interconvertible forms: - internal (atomic motion in solids, liquids & gases)

- electrical & magnetic

- surface

- chemical - in molecular bonds (coal power)- kinetic (wind power)

- potential – gravitational (hydropower)

- radiant (solar power)

- nuclear – in proton-neutron bonds (nuclear power)

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Energy and the First Law

• energy cannot be created or destroyed: conservation of energy

- Mayer (1842) - Helmholz, Clausius, (ca 1850)

•energy is related to heat and work

by the

• Energy is a property of a body; heat and work are not

1st Law of Thermodynamics

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The Second Law• Development of steam engines (Watt 1778)

showed empirically that heat cannot be completely converted to work

• Carnot (1824) showed theoretically

why this is so• proposed the concept of the

reversible processes• For an engine (of any kind) to

produce work, hot and cold reservoirs

are required to provide high-quality heat

and receive reject low-quality heat• practical cycles for producing

work are developed (Rankine,

Otto, Brayton) 19th Cent.

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By analyzing many experiments and processes involving transfer of heat, Clausius (ca 1850) uncovers a new thermodynamic property, which he names entropy

- related to the heat exchanged between system and surroundings- not related to work- places 2nd law in quantitative form

Qualitative statements:

Clausius: “It is impossible to convert heat completely to work”

Entropy and the 2nd Law

Kelvin – Planck: “It is impossible for any any engine to transfer heat from a cold source to a hot source without work being done”

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Chemical/Materials Thermodynamics• This branch deals with:

- multiple components, multiple phases- chemically reacting mixtures- equilibrium at conditions of fixed p and T

• Developed by Willard Gibbs (Yale Univ. 1890)• Gibbs introduces the chemical potential – the driving

force for:

- Chemical reactions

- Exchange of a species between phases- Diffusion of a species in a single phase

• At equilibrium, these

processes STOP

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Statistical Thermodynamics• Links atomic motions to thermodynamic properties

discovers the formula for the

absolute entropy Boltzmann (ca 1885)

Planck (~ 1900) quantization of energy states

Einstein, Debye (1905) – quantum mechanical explanation of specific heats of solids

Fermi, Dirac, Bose – quantum statistical thermodynamics

Giauque (1930, UCB)- the 3rd Law: The entropy of a body is zero at 0 K