Thermo 2Thermo 2Heat Engines + 2008 Test QuestionsHeat Engines + 2008 Test Questions

Key Idea

Heat is a form of energy

Heat can be transformed into work through a heat engine

VocabHeat

Thermal equilibrium

Specific heat

Thermal insulator

Thermal conductor

Calorimetry

Adiabatic

Isothermal

Isobaric

FORMULAS AND REFERENCE TABLES

ΔL = αLo ΔT

ΔV = βVo ΔT

Q = mc ΔT

ΔU = Q + W

W = P*ΔV

Efficiency = (TH – TC) / TH

TABLE OF SPECIFIC HEAT, HEAT OF VAPORIZATION & FUSION, and COEFFICIENT OF LINEAR EXPANSION

Material α (x1E-6 C-

1)Coeff. Linear

Expansion

Specific Heat (J/(g C)

Heat of Fusion (J/g)

Heat of Vaporization

(J/g)

Copper 16.5 0.385 205 5070Methanol 378 2.450 109 878Iron 11.8 0.450 266 6290Silver 18.9 0.235 104 2360Lead 28.9 0.130 20 86Water 69 4.184 334 2256

1. If you had to explain to someone what thermodynamics is all about, what would you say?

2. List the 4 Laws of Thermodynamics:

Oth:

1st:

2nd:

3rd:

3. You stir your coffee with a stainless steel spoon. You put the spoon in your mouth. You don’t burn your mouth, but the spoon is hot. You drink your coffee and unfortunately burn your mouth. Why do you burn your mouth with the coffee but not with the spoon, when they’re obviously starting at the same temperature?

4. Explain the following: You take a lump of lead and place it above a Bunsen burner. It begins to melt at 328C, and holds this temperature until all of the lead melts. After the entire lump is melted, the temperature rises. Why do you see a plateau on the warming curve?

5. What conditions must be true for a heat engine to be 100% efficient?

Carnot Cycle

6. A perfect insulator is called___________.

7. The Carnot cycle operated in reverse drives the__________________.

8. Use the table of specific heats on page 1 to identify a good heat conductor_____________________________________________.

9. Use the table of specific heats on page 1 to identify a good heat conductor____________________________________________.