The Wonders of Water

The wonders of water are so many and are crucial for life on earth. If our planet were only a little closer to or further from the sun, earth’s water would be either evaporated away or frozen as ice.

So many of our planet’s forms of life are dependent on an environment in which liquid water is stable. This means that the earth must not be too close or too far from the sun. Astronomers estimate that if the distance from the earth to the sun changed by as little as 2 percent, all life would be extinguished as water either froze or evaporated.

Another factor making life on earth possible is an unusual characteristic of water when it freezes into ice. Water is such a common substance that most of us do not stop to consider that the balance of life depends on its simple physical properties.

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The almost universal behavior for liquids is that when they get cooler, they become more dense, until their molecules virtually stand still. They freeze in their most dense state. Not water. What happens with water is that while it does get denser as it gets colder, when it reaches about 38° F the process stops. And when the temperature drops just six more degrees, it quickly expands and then freezes. That’s why ice floats.

One of the wonders of water is that it is one of the few substances that expands when frozen. Most substances when frozen become denser and sink when placed in a container of the same substance in liquid form. But this isn’t the case with ice in water. Since water expands by one tenth its volume when frozen, frozen water has the unusual characteristic of floating on top of liquid water.

When rivers and lakes freeze in the winter, they freeze at the surface, with the ice forming an insulating barrier that prevents the denser water underneath from freezing and thereby preserving aquatic life during very cold weather. If ice acted like almost all other compounds, it would sink, and rivers and lakes would freeze from the bottom up. All bodies of water would eventually become solid bodies of ice, eliminating most life as we know it.

Another property of water, just like density above which is weird is cohesion. The way the water molecule is formed and the nature of the elements from which it’s made result in creating a liquid with a surface “skin.” It’s this skin that dimples under the feet of the fascinating spider-like water strider, spreads its widening wake behind the zooming little water-boatman beetle, and forms the concentric circles advancing outward from the impact point of a child-thrown stone. Even a sewing needle can be made to float on the cohesive surface of water. This cohesion, or surface tension, also makes water form the droplets so vital to other life processes—especially important to the form and function of the living cell.

 

Adhesion. While cohesion causes water molecules to stick together, adhesion helps water stick to other things. We experience this when we try to separate solid glass sheets that have virtually bonded themselves with a thin layer of water. It takes a lot of energy to pull them apart.

It’s this same adhesive force that creates capillarity: the tendency of a liquid in a capillary tube or absorbent material to rise or fall as a result of surface tension.. Cohesion and adhesion, two wonders of water,  in tandem make water molecules sort of reach up and grab the sides of a tube, and seemingly in defiance of gravity, pull themselves upward, while at the same time they reach down and grab fellow molecules and pull them along. It’s this property that allows water to move up through living plants and move the way blood moves through the capillaries of our bodies.

Water is the earth’s thermostat and the human body’s thermal regulator. With other similar substances, water would be expected to become a gas at room temperature. It’s wondrous thing that life exists because it doesn’t. Some water, however, does escape the surface of its liquid state and become vapor through the process of evaporation. Evaporation cools the surface area where it occurs. How it does this is itself a wonder: Heat applied to the surface of water causes the top molecules to “dance” with the higher temperature. Eventually these heat-energized molecules vaporize, rising like hot air balloons. This leaves behind the cooler molecules, lowering the temperature of the body from which it has escaped.

Water also stores heat extremely well and gives it up reluctantly. Water’s ability to store heat and then hold it is just one more way that it supports life on earth. If it didn’t make up nearly 80 percent of the earth’s surface and didn’t store heat, the earth’s temperature fluctuation would become so extreme that all life would quickly cease to exist.

One of the wonders of water is its property of being a solvent: it is called the universal solvent. Virtually all the naturally occurring elements have been found dissolved in water, from calcium to phosporous. And it’s clearly no accident that the most common elements in water are the most common elements in the human body. Up to 60% of the human adult body is water. According to H.H. Mitchell, Journal of Biological Chemistry 158, the brain and heart are composed of 73% water, and the lungs are about 83% water. The skin contains 64% water, muscles and kidneys are 79%, and even the bones are watery: 31%.Of all the work that water does in, around, and for people, one of its most important jobs is its capacity to carry to every human cell the dissolved nutrients and critical components we need to live and remain healthy.

 

Source: Wikipedia