Chemistry Reference
In-Depth Information
Figure 10.15.
Schematic representations of important wetting processes: (a) adhesion; (b)
spreading; (c) immersion.
increases by an equal amount. The interfacial area between L
1
and L
2
also increases
during the process. The change in interfacial area in each case will be the same, so
that the total decrease in the energy of the system will be
G
¼
A
ðs
SL
2
s
SL
1
s
1
=
2
Þ
ð
10
:
5
Þ
where
s
1/2
is the interfacial tension between fluids 1 and 2. If the term in parenth-
eses, defined as the spreading coefficient S (see Chapter 8) is positive, then L
1
will
spontaneously displace L
2
and spread completely over the surface (or to the greatest
extent possible). If S is negative, the spreading process as written will not proceed
spontaneously.
