LECTURE PHYSICAL CHEMISTRY 3rd EDITION ROBERT G. MORTIMER

www.daykemquynhon.ucoz.com
2.7. Calculation of Enthalpy Changes of a Class of
Chemical Reactions
A chemical reaction involves the breaking of some chemical
bonds and/or the formation of other chemical bonds. The
breaking of bonds requires an input of energy and the
formation of bonds gives off energy, so that nearly every
constant-temperature chemical reaction is accompanied by
energy and enthalpy changes.
- If the system gives off heat when a reaction takes place at
constant temperature, the reaction is called exothermic.
- If the system absorbs heat at constant temperature, the
reaction is called endothermic.
In this chapter we will consider only chemical reactions in
which every reactant or product is either a gas or a pure liquid
or solid, and we will assume that all gases are
ideal gases. Three reactions in this class are:
https://plus.google.com/+DạyKèmQuyNhơn
Collected by Nguyen Thanh Tu Teacher
MailBox : nguyenthanhtuteacher@hotmail.com