Little-Known but Essential Properties of a Meager Molecule
In our journey through life, it’s often everyday things that we most take for granted. In his latest book, The Miracle of Man: The Fine Tuning of Nature for Human Existence, biochemist and physician Michael Denton turns his attention to water, the substance essential to all life on Earth. Denton reveals a raft of properties unique to this miracle substance and shows how it reveals nature’s prior fitness for complex creatures such as human beings.
Water – composed of two hydrogen atoms and one oxygen atom – is one of the most common substances on Earth, but its properties are extraordinarily rare. Hydrogen derives from the beginning of the cosmos, whereas oxygen came a little later, after the first stars were forged. Forget the Antiques Road Show: Water is the ultimate antique, far more ancient than ordinary human understanding. But there’s more, much more.
Water can dissolve an enormous number of different kinds of substances, including salts, a whole suite of gases, sugars, amino acids, and other life-essential substances. The key to understanding water’s amazing propensity for dissolving stuff lies in its polar nature.
When hydrogen combines with oxygen, the shared electrons that forge the bonds between the atoms are unequally shared, with the result that the larger oxygen atom holds onto those electrons more strongly than the smaller hydrogen atoms. So, the oxygen atom takes on a partial negative charge while the hydrogen atoms are imparted with a partial positive charge, resulting in a strongly electrically polarized molecule.
This slight asymmetry in the charge distribution in every water molecule is responsible for its ability to attract and hence dissolve a huge number of substances. Yet crucially, this polarity prevents other substances such as nitrogen in the atmosphere from dissolving to any appreciable degree in water. It also curtails the amount of oxygen capable of being dissolved. If this were not the case, our atmosphere would all but vanish, dissolved up in the vast oceans that cover 70 percent of the globe.
The wondrous solubility of water is also crucial for weathering land-based minerals locked inside rocks and distributing them throughout the biosphere in a way that allows plant, animal, and microbial life to flourish in regions of the Earth that would otherwise be inhospitable. The crucial reaction involves the dissolving of carbon dioxide from the atmosphere in rainwater, creating a weakly acidic solution that leaches those life-giving minerals out of rocks. Without this vital reaction, life would soon grind to a halt all over the planet.
Water’s strongly polar nature also means that it attracts other water molecules quite strongly. Indeed, compared with many other molecules of comparable size, water really ought to be a gas at ordinary ambient temperatures. The reason it isn’t is because water molecules glue to each other, increasing its density enough to keep it in liquid form over an impressively large range of temperatures (between 32- and 212-degrees Fahrenheit) – much of the range over which most life on Earth thrives.
Furthermore, the self-attracting property of water also makes it more viscous (thick or gloopy) than normal, thus rendering it less compressible. And it is this low compressibility that allows it to be pumped around the body by the human heart, ensuring life-giving nutrients and gases get delivered to deep body tissues via the circulatory system.
Remarkable Thermal Properties
Water also has one of the highest specific heat capacities of the millions of substances thus far characterised by chemists. This means that it soaks up lots of heat without registering much in the way of a temperature change. This is vitally important in maintaining our body temperatures within the narrow range needed for human survival. If water’s heat capacity were lower, even moderate exercise would plunge us into life-threatening hyperthermia, but if it were much higher the chemical reactions in our cells would never generate enough heat to keep our bodies warm enough to stay alive for more than a few minutes.
Water’s unique physical properties also contribute to keeping aquatic life on Earth warm enough during freezing winter conditions. Water possesses the highly unusual property of being denser when in the liquid phase compared to its solid, ice phase. As a result, ice floats on liquid water. If water were to behave like most other liquids, ice would sink to the bottom of our rivers and oceans with the result that vast amounts of fish and the larvae of myriad other aquatic creatures would freeze to death every winter, which would quickly cause the biosphere to collapse. What’s more, the layer of ice floating on water insulates the liquid beneath it, keeping water-based lifeforms warm during cold winter snaps.
The Connection to Oxygen
As remarkable as water’s properties are to maintaining all life on Earth, it’s also the source of practically all the oxygen present in our atmosphere. In a series of ingeniously complex biochemical reactions inside green plants, chlorophyll harnesses the energy of sunlight to split water vapor into molecular oxygen and hydrogen in a process known as photosynthesis, using the hydrogen to fix carbon dioxide from the atmosphere and transform it into sugars. The oxygen is then released as a waste product. In this way, water is foundational to maintaining all life on Earth, or anywhere else in the cosmos where God has allowed life to flourish.
Knowing what we now know about water from our ongoing scientific studies, it’s all the more remarkable that the Bible is replete with references to water as the medium of both physical and spiritual life. Water baptism symbolizes the cleansing of both body and soul. In the Gospel of John, Jesus tells the woman at Jacob’s well that he can provide water welling up to eternal life (John 4:4-14), and once again in Revelation, we see the imagery of the “river of life” flowing from the throne of God in the New Jerusalem, sustaining the fruitful trees, the leaves of which are for the “healing of the nations” (Revelation 22:1-2).
So, the next time we bathe or refresh ourselves with its vital properties, we ought to give thanks for this not-so-small mercy, the miracle of water – God’s liquid creation that sustains his wondrous creation.Neil English
is working on a new book, Choosing Binoculars: A Guide for Stargazers, Birders and Outdoor Enthusiasts, which will be published by Springer Nature in late 2023.• Get SALVO blog posts in your inbox! Copyright © 2023 Salvo | www.salvomag.com https://salvomag.com/post/the-wonder-of-water