M.Elizabeth Chemistry 2010-2011
Spring Semester February 14 - 18
Thermochemistry Chapter 16 in textbook and Chapter 13
- GUHS Thermochemistry SG word
- Chapter 16 Heat and Energy Glencoe ppt
- Thermodynamics Bellringers word
>> Heat notes word
>> Specific heat practice problems pdf
>> Phase Diagram pdf
Online Resources (Web Sites)
- Specific Heat of Aluminum link
- Internal Energy ChemTour
- Heating Curves ChemTour
- Bond Energy Animations and Explainations link
- Thermodynamics with Canadian Connections link
- Practice Questions on-line link
Chapter 16 contains the following units:
Heat in Chemical Reactions and Processes
Calculating Enthalpy Change
Energy is exchanged or transformed in all chemical reactions and physical changes of matter.
CA Standards for mastery
7a. Temperature and heat flow are described in terms of the motion of molecules (or atoms).
Temperature is a measure of the average kinetic energy of molecular motion in a sample. Heat is energy transferred from a
sample at higher temperature to one at lower temperature. Often, heat is described as flowing from the system to the
surroundings or from the surroundings to the system. The system is defined by its boundaries, and the surroundings are outside
the boundaries, with “the universe” frequently considered as the surroundings.
7. b. Chemical processes can either release (exothermic) or absorb (endothermic) thermal energy. Endothermic processes
absorb heat, and their equations can be written with heat as a reactant.
Exothermic processes release heat, and their equations can be written with heat as a product.
The net heat released to or absorbed from the surroundings comes from the making and breaking of chemical bonds during a
reaction: breaking a bond always requires energy and making a bond almost always releases energy. The amount of energy per
bond depends on the strength of the bond.
The potential energy of the reaction system may be plotted for the different reaction stages: reactants, transition states, and
products. This plot will show reactants at lower potential energy than products for an endothermic reaction and reactants at
higher potential energy than products for an exothermic reaction. A higher energy transition state usually exists between the
reactant and product energy states that affect the reaction rate.
7. c. Energy is released when a material condenses or freezes and is absorbed when a material evaporates or melts. Physical
changes are accompanied by changes in internal energy. Changes of physical state either absorb or release heat. Evaporation and
melting require energy to overcome the bonds of attractions in the corresponding liquid or solid state. Condensation and freezing
release heat to the surroundings as internal energy is reduced and bonds of attraction are formed