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Name: William T.
Status: educator
Age: 40s
Location: N/A
Country: N/A
Date: 1999-2001


Question:
I have both read and heard that we are dealing with the same amount of water in the world that has always been here since the world was formed. Is this true? If this is true, Why do we have free hydrogen and free oxygen atoms? Why don't they bond into a water molecule? What about the hoards of kids (of all ages) who have, by using electric current, seperated the atoms of the water molecule and subsequently demonstated to the neighborhood the volatile properties of the hydrogen? Is there some saturation point within the relatively closed eco-system of the earth that requires the recombination of those then free oxygen atoms?


Replies:
William,

Apart from any liquid waste which might have been released into space by astronauts and not returned to our atmosphere, I think your comment regarding a stability in the amount of water, or its component atoms, is correct.

Since the beginning of time there has been a water cycle in evaporation and precipitation, and subsequently the capture of hydrogen and oxygen molecules from water into simple and complex sugars of photosynthesis. You could think of this as that perhaps an atom of oxygen once breathed by ancient peoples might, with good likelihood, currently be present in your lungs. That same atom might, however, also be present feet-deep in the wood of a sequoia somewhere in California or riding along in the currently-hovering space shuttle. The message here is that the earth is the great recycler, that more or less the component atom count remains stable.

A chemist could detail the reasons free hydrogen and free oxygen may be present without bonding...note that since the earth is comprised of literally billions and billions of ongoing chemical reactions, it is understandable that products of these reactions, viewed in a snapshot of time, could be present in somewhat unstable states. In the absence of a trigger (consider the Hindenburg) hydrogen and oxygen will not instantly mix and form water....with the addition of a spark, however, water is formed with a great release of energy.

For your question about the neighborhood demonstrations of electrolysis, consider the volumes you are discussing as being like a drop in the ocean. Those relatively miniscule volumes of gas indeed become mixed into the "air" and become incorporated in everything from plant and animal tissue to the dust on your tabletop. Unstable atoms do indeed react with other unstable atoms to reach more-stable states. (Consider the production of oxone resulting from lightning strikes and subsequent bonding of the freed oxygen atoms.)

The message I am giving here should not be misinterpreted. No one should consider the earth's environment as limitless...we have all discovered in the recent past that wastes we thought would be diluted to safety in our 'limitless' environment have begun to accumulate within cities' air and nearby city waste centers. The immense volumes and greater toxicity of some of those materials, however, creates the difference in how effectively they are diluted in the environment to levels of safety. Volumes of the gases you mention, while present, are present usually shorter-term and in only minor degrees in the air we breathe. Note, however, if every person in every neighborhood suddenly gave an electrolysis demonstration, we could indeed notice a pollution event. As a side issue, in fact, there is ongoing discussion of levels of pollution resulting from poorly-running lawn care equipment; used on a city-wide scale, these machines could adversely impact air quality, again, because of the volumes and hazards of the gases produced.

Thanks for using NEWTON!

Ric Rupnik


No, it Is not true. It Is approximately true, but not strictly true.

Water can still enter the earth from icy meteors. (There is debate currently on how rare these actually are.) Also, the fossil fuels of the earth's crust contain hydrogen (bonded to carbon atoms), which creates water when burned. Conversely, every day, the earth's green plants consume water and carbon dioxide to make oxygen and sugars. In time, most plant tissues will decompose back to water and carbon dioxide, so the water consumed will eventually be re-formed, but that's not the same thing as saying that all water molecules have been water molecules for the last 4.6 billion years.

Free hydrogen gas (H2, not hydrogen atoms) actually is light enough to escape the atmosphere. So, some of the water electrolyzed by kids' experiments is forever lost to the world.

Richard E. Barrans Jr., Ph.D.
Assistant Director
PG Research Foundation, Darien, Illinois


William,

Free hydrogen and oxygen atoms do not exist in any appreciable amounts in earth's atmosphere -- in fact, they are quite rare. Gaseous hydrogen (molecules, as opposed to free atoms) lack sufficient mass to be held by earth's gravity. Like helium, hydrogen released into the atmosphere is lost to space. Thus, we have insufficient concentrations of H2 and O2 reactants to form significant amounts of water in our atmosphere.

In addition, placing the gases together is not all that is required to make them react. They must be nudged with "activation energy" to trigger their reaction. As demonstrated by numerous science fair projects involving the electrolytic dissociation of water, H2 and O2 when mixed in the correct proportions can react explosively when initiated by a tiny spark.

When hydrogen and oxygen do react to form water, a great deal of energy is released. In order for one to dissociate water into hydrogen and oxygen, that same amount of energy must be expended to accomplish the dissociation. The second law of thermodynamics tells us that in such a process, we can't even break even. In other words, it would be hopelessly inefficient to make electricity by conventional means and then to use that electricity to electrolytically dissociate water into hydrogen and oxygen as a new fuel source. We would "spend" more energy than we would gain.

Scientists are searching for a low energy pathway that can lead to the dissociation of water into its elements. If they are successful, the world's energy economy could be relatively pollution free when the hydrogen and oxygen are combusted to form only water. Alas, there are no such activities that are entirely pollution free. In the world of energy conversions, there is no free ride.

Just as civilization used the horse (fueled by oats) and the tractor (fueled by gasoline) to accomplish work to difficult to be performed by hand, science is seeking a way to harness other workers to do our bidding. The photodissociation of water assisted by certain kinds algae is an area being investigated. If we can use sunlight and the assist of plants in place of fossil fuels to separate water into its elements, we might be on our way to a hydrogen-based economy.

Search the Internet for information on hydrogen fuel cells. There is much out there that you will find of interest.

Regards,
ProfHoff


Considering the Universe in its totality, hydrogen is by far the most abundant element, with helium being second. Yet both of these elements in their free state are present in our earthly environment in very small amounts. So there is not much free hydrogen around.

Geologically speaking, the amount of water present on the globe may now be pretty much constant; however, we cannot say with any certainty that this was the case many millions of years ago during the earth's formative years. Indeed the amount of "fresh water" is being consumed at an alarming rate. There is an article on this subject in a recent issue of Scientific American.

In our ecosystem oxygen is involved in a number of global cycles: manmade combustion converting it to CO2, the production of O2 by plankton, plants etc., two mention just two. In the short term this is a steady state, but not necessarily a stable one in the long term.

The amount of O2 and H2 generated by electrolysis is globally insignificant, and in the atmosphere, the relatively large excess of O2 does combine with any free H2 rather quickly to reform water.

Vince Calder



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