Just Enough Chemistry: Water’s Life Supporting Properties

Water’s States: Gas, Liquid, and Solid

Ice floating is especially significant to life in temperature zones. This includes the biome in which I live, here in upstate New York.  We experience relatively hot summers. These summers encourage the growthAn increase in size and number of cells. of organisms. We also have particularly cold winters. These winters can kill many animals and plants.  Because ice floats, a thin layer of ice forms on the surface of a lake. It insulates the rest of the lake, allowing aquatic life to survive the winter.  The ice acts like an insulating blanket, containing the heat generated by the life forms.  Alternatively, the ice reflects the sun’s heat, relating to the shrinking polar ice caps and increasing global temperature.

Water’s Heat of Vaporization

There are so many ways in which this impacts your life.  If you live near a body of waterThe universal solvent essential for life. like an ocean or large lake, you may have noticed something. The temperatures are cooler near the water.  Defrosting frozen meat in water takes a shorter amount of time. This reduces the time your uncooked meat spends in the ideal temperature for bacterial reproductionThe process of producing offspring..  And, most importantly, your water-based blood does not boil and evaporate when you walk out into the sun.  Your body uses water-based sweat to bring heat to the surface of your body. This sweat allows evaporation to cool your body. Dogs pant to achieve the same effect.  As a personal example, I grew up at the Jersey Shore, surfing year-round.  Like, I remember walking to the ocean through the snow on the beach.  So, as a surfer, I acquired wetsuits of variable thickness.  But the best thing I found was a two-wetsuit combo.  By wearing two suits, you’d get this insulating layer of water between the two.  And since your urineThe liquid waste excreted by the kidneys. is water based, it is pretty hot. Wearing two suits and peeing as soon as you get out into the water guaranteed warmth for hours. 

Water’s Solvent Properties

Water has an incredible ability to dissolve many substances and is known as the Universal Solvent.  Let’s review for a moment: solutes dissolve into solvents to make solutions.  By dissolving carbon dioxide into water, we have seltzer.  Adding salt makes club soda, and adding quinine makes tonic water.  Seawater and blood are both solutions with water as the solvent and ionsCharged atoms or molecules., biomolecules, and other substances as the solutes.  Your cellsThe basic structural and functional units of life. are essentially small packets of water that contain a complex solutionA homogeneous mixture of two or more substances. of moleculesGroups of atoms bonded together. dissolved within the water.

Substances that dissolve in water or are attracted by water are called hydrophilic. Think of all the substances that dissolve in water or absorb water: rice, pasta, bread, cotton towels, paper towels. These substances are known as hydrophilic, or water-loving.  Two substances you are familiar with that do not dissolve in water are waxes and oils. Water beads up on waxy surfaces and the oil in salad dressing rises above the watery vinegar.  This is why you should use a blender to emulsify your salad dressings.   Think of all the substances that are hydrophobic: olive oil, butter, many lotions, cleaners, and rain-proof clothing.  Substances that do not dissolve in water or repel water are called hydrophobic. Both hydrophilic and hydrophobic substances can be found in living systems. 

Water’s Cohesive and Adhesive Properties

Water exhibits the two properties of cohesion and adhesionThe tendency of water molecules to stick to other substances..  What’s the difference?  Think of the root words.  Ad: adjacent, adjunct, additional.  And Co: cohabitate, coordinate, co-captains.  Cohesion is a water molecule’s ability to stick to another water molecule, causing surface tension.  This is what causes that nasty skinThe body’s largest organ, providing protection and regulation. on the soup in a cafeteria.  The solutes like seasonings in the soup are attracted to the surface tension at the air-water interface.  This surface tension forms a boundary layer. It is strong enough to support small insects. It also supports snails and other small organisms as a surface habitat. Adhesion is a property of water that allows it to stick to different surfaces. These surfaces include the cotton of your jeans, the sides of a capillary tube, or a hydrophilic paper towel. 

In factA statement based on direct observation that is repeatedly confirmed., this property can cause capillary action where a water-based substance rises through a small tube.  The cotton of your jeans are essentially small tubes.  On your way to class you step in a puddle and get the bottom of your jeans wet.  As you sit in class, the wet mark seems to rise up your jeans, defying gravity. When you get up to leave, it looks like you stepped in a puddle that was two feet deepAway from the surface of the body.. This mechanism is also at work in the large redwoods. It enables them to draw water and nutrients from the soil. They transport these to the leaves without an active pump.