Skip to main content
This is the Universe’s most incredible molecule

We can't live without it.
This article was written by Richard Gunderman from the Indiana University-Purdue University Indianapolis, and was originally published by The Conversation. 
It’s the second most abundant substance in the Universe. It dissolves more materials than any other solvent. It stores incredible amounts of energy. Life as we know it would not be possible without it. And although it covers more than 70 percent of Earth’s surface, many parts of the world are in dire straits for lack of it. What is it?
The answer, of course, is water. In some ways, water is one of the substances we know best, in part because it makes up 75 percent of our bodies. Every day we drink it, bathe in it, clean with it and use it to dispose of our wastes. Yet scientists are still striving to understand many of water’s remarkable properties, and the 21st century will force us to think about water like we never have before.
For most of human history, water was considered to be one of the four elements, along with air, earth and fire. It was only in the 18th century thatchemist Antoine Lavoisier passed an electrical current through water and realised that it gives off two gases: hydrogen (literally, 'water maker') and oxygen.
The formula of water is H2O - two atoms of hydrogen and one of oxygen. One of water’s most remarkable properties is traceable to the hydrogen bonds that continually form and reform between its slightly negatively charged oxygen and slightly positively charged hydrogen components. Thanks to these bonds, water molecules attract one another far more strongly than those of almost any other substance.
These hydrogen bonds give water a very high specific heat, meaning that it takes a great amount of energy to warm it. It also has a remarkably high boiling point compared to other chemically similar molecules, such as hydrogen sulphide. These properties enable human beings to dissipate large amounts of heat during exercise by perspiring.
Another consequence of hydrogen bonding is capillary action (the topic ofEinstein’s first paper), which occurs, for example, when a liquid is drawn up between the hairs of a paintbrush. The water molecules attract one another so strongly that they defy the force of gravity. When water evaporates from the highest leaves of a tree, it draws up other water molecules from the roots far below.
Still another consequence of hydrogen bonding is water’s high surface tension. This accounts for its tendency to form droplets and enables some insects literally to walk on water. This force can be so strong that premature infants, who lack surfactant, a substance that lessens it, can become exhausted just trying to inflate their lungs. Fortunately, surfactant is now available as a medication.
The fact that water has slightly positively and negatively charged poles also makes it the 'universal solvent', perfect for dissolving salts, sugars, acids, alkalis and even gases such as carbon dioxide, accounting for the fizz in sodas. Such substances are known as hydrophilic (water-loving), precisely because they dissolve so easily in water.
By contrast, fats and oils are classified as hydrophobic, because they do not have electrical charges at their ends. As a result, they are attracted more strongly to one another than to water. To wash such substances from our hands or clothes, we need soaps, which have both hydrophobic and hydrophilic ends that help break them up into tiny droplets that can be carried away by water.

From one state to another

Even more remarkably, water is practically the only substance known to scientists that, as it cools from its liquid to solid state, actually expands. Virtually every other substance becomes denser as it 'freezes', but thanks to this remarkable property, ice cubes float in our drinks. More importantly for living organisms, lakes and other bodies of water freeze from the top down.
Ice’s remarkably low density is attributable to the fact that water molecules need thermal energy to maintain the random orientations they assume in liquid water. As the temperature decreases, the molecules begin to line up in a regular latticework. To do so, however, the distance between them must increase. As a result, ice is about 9 percent less dense than liquid water.
The adage that no two snowflakes are alike seems hard to believe until you consider the fact that the patterns in which water molecules freeze vary depending on temperature and humidity. When you add the fact that the average snow crystal contains about 10 quintillion (10 followed by 18 zeroes) water molecules, it is easy to see why the number of possible combinations is unimaginably large.

A continuous cycle

Water is also incredibly dynamic, continuously moving all over Earth in a cycle of evaporation, condensation, precipitation and runoff back to seas and lakes. The same is true among living organisms, where the hydrogen and oxygen constituents of water are continually combining and recombining through the processes of photosynthesis and respiration.
And while we cannot live without water, it should also be said that we are water producers. Each time we break down a molecule of glucose, we produce six molecules of water, a reaction that takes place in the typical human body about six septillion (6 followed by 24 zeroes) times per day. Even so, we still don’t produce enough water to meet our own needs.
Although droughts in the western US are garnering considerable attention today, it is likely that water will become an even hotter topic over the course of this century. For one thing, only about 3 percent of Earth’s water is fresh water, the other 97 percent being found in the oceans. And about 70 percent of this fresh water is found in glaciers and the ice caps of Antarctica.
As a result, even though Earth holds enough water to make a sphere about 860 miles (1,384 km) in diameter, only a tiny percentage of this water is easily accessible to human beings, and increasing shortages loom in the future. Some scientists have predicted that, as some point in the 21st century, fresh water will become a more valuable commodity than petroleum.
A saying often misattributed to Albert Einstein claims there are two ways to lead a life. The first is as though nothing is a miracle, and the second is as though everything is a miracle. Water is entirely natural, hugely abundant and so necessary to life that our cells are bathed in it. Yet it is also so remarkable that, as a physician and scientist, I regard it as little short of miraculous.
The ConversationRichard Gunderman, Chancellor's Professor of Medicine, Liberal Arts, and Philanthropy, Indiana University-Purdue University Indianapolis
This article was originally published on The Conversation. Read the original article.

Comments

Popular posts from this blog

Where the Swastika Was Found 12,000 Years Before Hitler Made Us Uncomfortable About I

Minoan pottery from Crete. The Minoan civilization flourished from 3,000 to 1,100 B.C. (Agon S. Buchholz/Wikimedia Commons) ) Swastika from a 2nd century A.D. Roman mosaic. (Maciej Szczepańczyk/Wikimedia Commons A srivatsa (swastika) sign at Nata-dera Temple, Japan. (Cindy Drukier/Epoch Times) From the Sican/Lambayeque civilization in Peru, which flourished 750 to 1375 A.D. (Wikimedia Commons) Ancient Macedonian helmet with swastika marks, 350-325 B.C., found at Herculanum. (Cabinet des Medailles, Paris/Wikimedia Commons) A Buddha statue on Lantau Island, Hong Kong with a swastika symbol on the chest. (Shutterstock*) A 3,000-year-old necklace found in the Rasht Province of Iran. (Wikimedia Commons) The aviator Matilde Moisant(1878-1964) wearing a swastika medallion in 1912; the symbol was popular as a good luck charm with early aviators. (Wikimedia Commons) A mandala-like swastika, composed of Hebrew letters and surrounded by a circle and a mystica...

20,000 megawatts under the sea: Oceanic steam engines

Jules Verne mused about getting energy from heat in the ocean  (Image: Marc Pagani/Getty) Jules Verne imagined this limitless power source in Victorian times – now 21st-century engineers say heat trapped in the oceans could provide electricity for the world IF ANY energy source is worthy of the name "steampunk", it is surely ocean thermal energy conversion. Victorian-era science fiction? Check: Jules Verne mused about its potential in  Twenty Thousand Leagues Under the Sea  in 1870. Mechanical, vaguely 19th-century technology? Check. Compelling candidate for renewable energy in a post-apocalyptic future? Tick that box as well. Claims for it have certainly been grandiose. In theory, ocean thermal energy conversion (OTEC) could provide  4000 times the world's energy needs in any given year , with neither pollution nor greenhouse gases to show for it. In the real world, however, it has long been written off as impractical. This year, a surprising number of pro...

There’s a Previously Undiscovered Organ in Your Body, And It Could Explain How Cancer Spreads

Ever heard of the interstitium? No? That’s OK, you’re not alone  —  scientists hadn’t either. Until recently. And, hey, guess what  —  you’ve got one! The interstitium is your newest organ. Scientists identified it for the first time because they are better able to observe living tissues at a microscopic scale, according to a recent study published  in  Scientific Reports , Scientists had long believed that connective tissue surrounding our organs was a thick, compact layer. That’s what they saw when they looked at it in the lab, outside the body, at least. But in a routine endoscopy (exploration of the gastrointestinal tract), a micro camera revealed something unexpected: When observed in a living body, the connective tissue turned out to be “an open, fluid-filled space supported by a lattice made of thick collagen bundles,” pathologist and study author Neil Theise  told  Research Gate . This network of channels is present throughout ...