Photochemistryis
the study of
chemical reactions resulting
from the exposure
of light radiations. Light
supplies the required energy to take place the photochemical reactions.
The visible and
UV radiations (2000-8000Ǻ
wavelength) are mainly
used in photochemical reactions.
All photochemical
reactionstake place in
two steps.
In the firststep, the
reacting molecules are activated
by absorption of
light.
In the
second step, the
activated molecules undergo a
photochemical change.
For example, in the combination of hydrogen and chlorine,
the first step is
Cl2+ hv→2Cl.
The activated chlorine atoms (Cl.)then undergoes chemical
reaction
It is evident from the above reaction that the second step
can occur in absence of light.
Characteristics of photochemical reaction:
1.Photochemical reactions take place by absorption of light.
2.When a light
composing number of
colours is used,
the photochemical reaction
may not be initiated by all colours.
3.The free energy
change of a
photochemical reaction may
be either negative or positive.
www.svce.ac.in
Youtube.com
No comments:
Post a Comment