Notes
• “Normal Week”: Office Hours, Help Sessions
Except:
• Colloquium Tomorrow: “Manipulating Tc in Fe-Based
Superconductors”, 4pm, NSH 118
– Will have Office Hours from 5-6pm.
p
• Old notes added to web pages for Chapters 17, 18.
• Please look over exams
exams, turn in Re-Grades
Re Grades soon
Chapter 20: Heat and the First Law
of Thermodynamics
• Heat: “Energy that flows between a system and its
environment
i
t because
b
off a temperature
t
t
difference
diff
between them.”
The First Law of Thermodynamics
In any thermodynamic process between equilibrium states i and f,
the
h quantity
i Q+W
Q
h the
has
h same value
l for
f any pathh between
b
i and
d
f. This quantity is equal to the change in value of the state
function Eint , the internal energy of the system
system.
Heat Capacity
Heats of Transformation
To measure the specific heat of lead, you heat 600g of
lead shot to 100°C and place it in an aluminum
calorimeter of mass 200g that contains 500g of water at
an initial temperature of 17.3°C. If the final
temperature of the mixture is 20.0°C, what is the
specific heat of lead?
Assuming a drop of 50m, how much warmer is the
water at the bottom of Niagra Falls than at the top?
A 200g aluminum calorimeter contains 500g of water at
20.0°C. Aluminum shot with a mass of 300g is heated to
100°C and is then placed in the calorimeter. Find the
final temperature of the system, assuming that there is
no heat transfer to the surroundings.
Specific Heat Demo
How much heat is needed to change 1.5 kg of ice at
-20°C completely into steam?
A pitcher of lemonade has been sitting in the sunlight all
day and has reached a temperature of 33°C. You pour
0.24 kg into a Styrofoam cup and add 2 ice cubes (each
of mass 0.025 kg at 0.0°C.)
a)Assuming
)
g no heat is released to the surroundings,
g,
what is the final temperature of the mixture?
b)What is the final temperature if you add 6 rather than
2 ice cubes?
Work done by an Ideal Gas
Categories of Work for an Ideal Gas