Environmental Enlightenment #120
By Ami Adini - Reissued June 2, 2009
is a SHORT, LIGHT and SIMPLE newsletter. Its purpose is to rekindle in
the initiated terminology they have once learned, and enlighten the uninitiated on terms they may have heard but never knew the meaning of.
We use Henry’s Law to extract contaminants from soils and groundwater.
the diagram below, the two containers have liquid in the bottom and gas
above the liquid. Pressure P2 in the right-side container is greater
than P1 on the left.
At P2, more gas dissolves into the liquid.
It is a dynamic equilibrium: at every instant, the number of molecules
jumping into the air equates the number diving into the water.
Henry’s Law says:
The amount of a gas that dissolves in a liquid is proportional to the
pressure of the gas over the liquid (provided no chemical reaction
takes place between the liquid and the gas).
The law is named after William Henry (1774–1836), the English chemist who first reported the relationship.
Gas is a substance that has no definite shape or volume, with high energy particles flying continually at random.
is one of the three basic states of matter (solid, liquid, or gas)
where matter can expand indefinitely to completely fill its container.
Oxygen, nitrogen, carbon dioxide, hydrogen sulfide, superheated steam, chlorine, and radon are gasses, to name a few.
are made of atoms and molecules. These particles are in continual
motion — slow in solids, faster in liquids and faster in gasses. The
particles collide with each other and collide with the walls of the
containers. These collisions create pressure. (PB is the pressure inside the balloon.)
the open atmosphere the pressure of a gas is exerted by its weight over
a given area. At sea level, air places a weight of 14.7 pounds on every
square inch. That is 500 pounds of air pressing on your head.
reason your head has not sunken between the shoulders is that we live
in a sea of air, where the pressure equalizes on all sides. (If you
should examine individual tissues of your body you’d find them squeezed
at the rate of 14.7 pounds on square inch of each side).
are a number of gases which make up air. Of these, nitrogen and oxygen
make up 78% and 21% respectively. Thus, in atmospheric air, oxygen
contributes 21% to the total pressure, and it will dissolve in
open-face water in accordance with this pressure.
you were to create an atmosphere of 100% oxygen above water, oxygen
would dissolve 5 times as much, but as soon as you placed that
oxygen-impregnated water in open air, the oxygen would escape until an
equilibrium was struck between that which is dissolved in the water and
that which is hovering above.
It is a dynamic equilibrium: at every instant, the number of oxygen molecules jumping out would equate the number diving in.
say that when the above equilibrium is reached, the pressure of the
oxygen inside the water equates its pressure outside in the air.
volatile substance is one that is capable of being evaporated or
changed to a vapor at a relatively low temperature. A vaporized
substance behaves like gas.
ether, alcohol, gasoline, turpentine, benzene, paint solvents, are all
volatile. The volatility of a substance is the speed at which its
molecules collide internally. Some are more volatile than others.
substances dissolve in water. The dissolved substance will stay in the
water as long as the pressure it creates inside the water does not
exceed the pressure of that same substance in the environment
surrounding the water.
example, a gasoline tank leaks. The gasoline trickles down to
groundwater and partially dissolves in the water. Just above the water,
the soil is impregnated with gasoline vapors. An equilibrium ensues. If
you now suck the gasoline from the soil, the equilibrium is no more and
gasoline will start moving out of the water. We use Henry’s Law to design the vacuum system.
physical universe does not tolerate excellence. The goal is to move all
present into a dispersed equality of apathetic inaction, expressed well
in the laws of energy, thermodynamics and nuclear physics, and
manifested in every crumbled rock, alluvial fan and fossiled organism.
Henry’s Law is just another expression of same. It is only Life that
makes the antidote, elevating dirt into animated states of being,
capable of a predetermined effort converting dust into computer chip,
space shuttle and giant metropolis.
You can find past issues of our "Environmental Enlightenment" at amiadini.com
Wealth of information about environmental site assessments in the real
estate transactions and issues concerning assessment and cleanup of
contamination in the subsurface soil and groundwater.
Call me if you have any questions. There are no obligations.
Ami Adini & Associates, Inc.
Underground Storage Tank Experts
323-913-4073; 323-667-2336 fax
Ami Adini is a mechanical engineer, California Registered Environmental
Assessor, Level II, and president of AMI ADINI & ASSOCIATES, INC.
(AA&A), an environmental consulting firm specializing in all phases
of environmental site assessments, rehabilitation of contaminated sites
and upgrading of underground storage tank facilities. AA&A
specializes in practical solutions to environmental concerns using the
highest standards of ethics and integrity while providing its clients
with maximum return on their investments.