Lesson Plans

Chemistry: The Central Science 9th Edition ©2003

by Brown, LeMay, and Bursten

Week 5: Thermochemistry

Chapter 5: Thermochemistry

This lesson builds the basics of chemical thermodynamics, which will be dealt with more completely later in the course.

College Board Performance Objectives:

• Understand what the system, the surroundings, and the universe mean.
• Be familiar with the units of energy.
• Understand what the First Law of Thermodynamics means.
• Be familiar with how the internal energy of a system is affected by exchanges of heat and work between the system and the surroundings.
• Understand what a state function is.
• Define enthalpy, and explain how heat transfer from or to the system at constant pressure changes it.
• Know what the sign of the enthalpy indicates about the reaction.
• Be able to sketch an enthalpy diagram for reactions given their enthalpy changes.
• Be able to calculate the amount of heat released or absorbed by a reaction, knowing the quantity of the reactants and the enthalpy of the reaction on a mole basis.
• Define heat capacity and specific heat (capacity).
• Be able to work problems on calorimetry.
• State and apply Hess's Law of Constant Heat Summation in calculating enthalpies of reaction from enthalpies of other reactions.
• Know what the standard state of an element or compound is.
• Define and illustrate what is meant by standard enthalpy of formation.
• Calculate the enthalpy change of a reaction using a table of standard enthalpies of formation.

College Board Lab Objectives:

• Become familiar with the use of a calorimeter to measure the enthalpy change during a chemical reaction.
• Compare the molar enthalpy change for the neutralization of a strong and a weak acid.

Suggested Labs:

• Experiment 26, Heat of Neutralization, p. 299

Resources:

• Instructor's Resource Manual, p. 55–65
• Student's Guide, p. 80–101
• Test Bank, p. 169–210
• Instructor's Resource CD, Chapter 5

Pacing Guide:

• Energy and Its Conservation—.5 day
• q, w, E—.5 day
• Enthalpy, H—.5 day
• Calorimetry—1 day
• Hess's Law—1 day
• H°; H_f°—1.5 days
• Block Scheduling
  Don't spend much time on Energy and Its Conservation or q, w, and E. The really important concepts begin with Enthalpy. Calorimetry, Hess's Law, H°, and H_f° need two solid blocks of time. Suggested exercises are critical to student learning.

Key Words:

Suggested Exercises:
Critical thinking questions and end-of-chapter activities are included in these exercises.

• pp. 188–197, # 1, 3, 11, 13, 17, 19, 21, 23, 25, 27, 29, 31, 33, 35, 39, 41, 43, 45, 47, 49, 51, 53, 55, 57, 59, 61, 63, 65, 67, 69, 71, 73, 75, 77, 90, 96.
• eMedia Exercises: pp. 196–197, # 115, 116, 119, 122.

Troubleshooting Tips/Error Traps:

• Section 5.8, Food and Fuels, is not essential for the exam.
• Don't spend much time on E, q, and w.
• Spend more time on enthalpy.
• Get students used to remembering that standard enthalpies of formation are molar.
• Balancing chemical reactions is essential and so are the physical states of all species in thermochemistry.