Water is the most precious natural resource that we have on this planet. It is an essential element that plays a major role in every aspect of our daily lives. For example, water is used for drinking, bathing, cooking, recreating, cleaning, manufacturing, and energy production (just to name a few). Without water, life as we know it would cease to exist. But just what is it about water that makes it so versatile, useful, essential, and unique?
Amount of Water on Earth
About 0.001% of all water on earth resides in the atmosphere as a vapor, about 1.762% of it exists frozen as glaciers and permanent snow, and about 98.237% of it is in liquid form. Water also finds its way into nearly every corner of the globe as well. It is stored in our rivers, lakes, and oceans as well as underneath our feet as groundwater. There is also water in every biological organism alive today, the food we eat, and the air that we breathe. The table below summarizes the locations and volumes of all of the water on earth:
|Water source||Water volume, in cubic miles||Water volume, in cubic kilometers||Percent of Freshwater||Percentage of Total Water|
Oceans, Seas, & Bays
Ice caps, Glaciers, & Permanent Snow
Ground Ice & Permafrost
Source: Igor Shiklomanov's chapter "World fresh water resources" in Peter H. Gleick (editor), 1993, Water in Crisis: A Guide to the World's Fresh Water Resources (Oxford University Press, New York). http://ga.water.usgs.gov/edu/earthwherewater.html
The Current State of Water
Water is one of those rare substances that exists in all three physical states at once on Earth. Water's high heat of vaporization (because of the hydrogen bonding between molecules) makes it very resistant to changing states, especially evaporation. This property also helps to ensure that water is in a liquid state at Earth's most common temperatures. It is also interesting to note that many other substances that have similar molecular masses and/or molecular structures, such as carbon monoxide and methane, are gasses are room temperature.
Water is a Polar Molecule
Due to the composition of water, it is a polar molecule whose structure is shaped like a tetrahedron. The polarity of water is caused by the uneven distribution of the cloud of electrons that are covalently shared between the oxygen and hydrogen atoms. The most electron dense area of the molecule is near the where the oxygen atom resides. The result of this asymmetric electron cloud is that that molecule is bent at about 104.45°. This causes one side of it to have a slightly positive charge while the other side to have a slightly negative.
Water's polarity is the key that allows intermolecular hydrogen bonding to occur. Because of this chemical property, the molecules are attracted to each other and form a hydrogen bond when in close proximity. The relatively weak hydrogen bonds give water nearly all of the unique and amazing properties that it has.
Water is The Universal Solvent
Water can dissolve more substances in it than any other material known to man. Being polar gives water its ability to dissolve many things easily. This is extremely important because many of the minerals that our bodies need to survive are found naturally dissolved in water. Water is the most important medium by which minerals such as calcium and magnesium can enter the body. If water wasn't polar, it could not dissolve other substances and it would not be able to sustain life on earth as we know.
Pure water also has a pH of 7. This means that the amount of hydrogen (H+) and hydroxyl (OH-) ions are exactly balanced. This makes pure water ideal for neutralized many strong acids (pH < 7) and bases (pH > 7). Having a neutral (or nearly neutral in most cases) pH also contributes to the ability of water to dissolve other substances.
Water Expands When it Freezes
What would the world be like if water didn't expand when it freezes? Well, I highly doubt that the world would even exist at all. Water is somewhat unique as it is one of the very few materials that increases in volume as it freezes. By expanding in volume by up to 9%, the density of water in it solid state is lower than it is in its liquid state. This gives ice the ability to float. This simple fact alone has significant implications.
The fact that ice is less dense than liquid water means that when the top of a lake freezes, it can actually insulate the rest of the water from freezing. This ice shield allows for life, and many chemical reactions, to continue to occur throughout the winter season.
Cohesion & Adhesion
Another amazing property of water is it's high surface tension. In fact, water's cohesion is the strongest among all of the known non-metallic liquids. Surface tension, or the inherent attraction between individual molecules of water due to hydrogen bonding, is a key property in allowing life to exist on our planet. Aside from allowing some insects to walk on water, water's natural property of cohesion allows it to defy gravity. How? Well, the surface tension is just strong enough to allow water to "pull" itself up through narrow tubes or even void spaces in soil.
It is this property that allows capillary action to occur in our groundwater. Since the void spaces in certain soils are so close together, water can naturally rise higher than the official water table in some fine grained soils. Capillary action is also the main way that plants "drink" water. Transpiration of water in plants can only occur when water is soaked up through the tiny tubes that exist in the plant's stem or trunk.
Water Has a Very High Specific Heat
Did you know that water has a strong ability to resist changes in temperatures? Water has the remarkable ability to absorb or release relatively large amounts heat energy without actually changing temperature very much. The specific heat of water is 4.186 joule/gram C° which is much higher than many of the other substances that we use everyday. This makes it the ideal substance to cool power plants, maintain homeostasis within our bodies, and protect the Earth from wild daily and seasonal temperature changes.
Physical Properties of Water at Atmospheric Pressure (US Units)
|Temperature||Density||Specific Weight||Dynamic Viscosity||Kinematic Viscosity||Vapor Pressure||Vapor Pressure|
It is truly amazing to think about how water has so many unique and amazing properties. Just thinking about the fact that life can even exist here on earth because of its properties is mind boggling. If just one of the key characteristics of this elixir disappeared, life as we know it would cease to exist. Water is indeed the most important substance that exists in our world.
Keith Whelan on October 12, 2019:
Read More From Owlcation
Great information! Thank you! Cheers!
Noredden Bishena on October 05, 2019:
The unique property that I am posuld by , is it possible to extract energy from the water molecule without changing it other properties? .
roy on January 10, 2019:
I was curios why I add usually 1000 gala month to my inground 30x16 screen enclosed pool monthly using the sq. ft. evaporation is in line for south florida screened full sun pool. gladly it is not a leak. sometimes there are varibles as wind rain humitity will change gallonage somewhat .thanks for info.
Menzeleli Mamane on August 15, 2017:
how do we then calculate the vapor
pressure in a closed system?
G Ivanova on January 02, 2015:
This has got to be one of the coolest hubs. So informative and useful I love it!
Koustubh on March 14, 2013:
Dale Anderson from The High Seas on October 17, 2012:
Voted up. Really interesting stuff.
Christopher Wanamaker (author) from Arizona on December 20, 2011:
Stephanie Henkel - I'm glad that you enjoyed my hub. Water really is very strange and unique. Thanks for reading!
Christopher Wanamaker (author) from Arizona on December 20, 2011:
Pcunix - That was a pretty interesting article. Thanks for sharing!
Stephanie Henkel from USA on December 20, 2011:
While water is everywhere, we seldom think much about it. I really enjoyed your article and learned some interesting facts about the importance of water and ice. Thanks for explaining so well the science behind some of water's properties.
Tony Lawrence from SE MA on December 20, 2011:
I read a very interesting article recently at ScienceDaily titled "Weird World of Water Gets a Little Weirder".
Check it out: http://www.sciencedaily.com/releases/2011/11/11110...