notesnotes • “normal week”: office hours, help sessions except: • colloquium tomorrow:...

Notes

• “Normal Week”: Office Hours, Help SessionsExcept:• Colloquium Tomorrow: “Manipulating Tc in Fe-Based c

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 turn in Re Grades soon• Please look over exams, turn in Re-Grades soon

Chapter 20: Heat and the First Lawof Thermodynamicsof Thermodynamics

• Heat: “Energy that flows between a system and its i t b f t t diffenvironment because of a temperature difference

between them.”

The First Law of Thermodynamics

In any thermodynamic process between equilibrium states i and f, h i Q h h l f h b dthe quantity Q+W has the same value for any path between i and

f. This quantity is equal to the change in value of the state function E the internal energy of the systemfunction Eint , the internal energy of the 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 no heat is released to the surroundings, ) g g ,what is the final temperature of the mixture?b)What is the final temperature if you add 6 rather thanb)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