solid
heat
solution
solid
solution
heat
CH-01
Rev. 0
Page 36
CHEMICAL EQUATIONS
DOE-HDBK-1015/1-93
Fundamentals of Chemistry
CHEMICAL EQUATIONS
This chapter will discuss the methods of qualifying solutions. The balancing
of the chemical equations will also be explained in this chapter.
EO 2.7
STATE Le Chatelier's principle.
EO 2.8
DEFINE the following terms:
a.
ppm
c.
Density
b.
Molarity
d.
Normality
EO 2.9
BALANCE chemical equations that combine elements
and/or compounds.
Le Chatelier's Principle
The effect of temperature on solubility can be explained on the basis of Le Chatelier's Principle.
Le Chatelier's Principle states that if a stress (for example, heat, pressure, concentration of one
reactant) is applied to an equilibrium, the system will adjust, if possible, to minimize the effect
of the stress. This principle is of value in predicting how much a system will respond to a
change in external conditions. Consider the case where the solubility process is endothermic
(heat added).
An increase in temperature puts a stress on the equilibrium condition and causes it to shift to
the right. The stress is relieved because the dissolving process consumes some of the heat.
Therefore, the solubility (concentration) increases with an increase in temperature. If the
process is exothermic (heat given off).
A temperature rise will decrease the solubility by shifting the equilibrium to the left.
How much solute is dissolved in a solution is very important when the solution is being made
for a specific use. To say there is a little, a lot, or a bit would not be very accurate if a specific
concentration is required. There are a few common and accurate methods used to express
concentration. These are density, molarity, normality, and parts per million.
