Properties of Water

Water has both cohesive and adhesive forces that are relatively strong. That is, its molecules are strongly attracted to one another and to many other kinds of molecules. What kind of bond forms between two different water molecules? 

• compound bond

• double bond

• hydrogen bond 

• ionic bond 

A florist places a bouquet of white carnations in water containing blue dye. After a time, the flowers turn blue. What process helped the carnations to change color? 

• water’s ability to form crystals 

• ability of H2O to dissolve NaCl 

• cohesion and adhesion of water molecules 

• formation of covalent bonds between hydrogen and oxygen molecules 

   

Small insects can walk across the surface of calm water. Their feet push the surface of the water down slightly, somewhat like a person walking across a trampoline, but they do not break the surface. What is the best explanation for why this happens? 

• The insects are light enough so that they do not break the hydrogen bonds holding the water molecules together. 

• The insects actually use their wings to hover slightly above the water’s surface and they only skim it with their feet. 

• The insect’s feet are non-polar, so they are repelled by the polar water molecules and are pushed away from the water’s surface. 

• The insects are small enough to see the individual water molecules, so they are able to step carefully from one molecule to the next. 

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The Gulf Stream is an ocean current that flows along Florida’s east coast. It has an 

important moderating effect on the climates of northern latitudes, particularly in Greenland, Canada, and Europe. What property of water makes the climate of these areas milder than they would otherwise be? 

• melting point 

•  high specific heat capacity 

•  polarity and electronegativity 

•  expansion of crystal structure as water freezes 

   

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Water is one of the most important substances for living things. One property of water that makes life on Earth possible is its high specific heat. How does the high specific heat of water affect the human body? 

• It moves fluids through arteries and veins. 

• It allows lighter materials to float in blood. 

• It makes it possible for substances to dissolve in cells. 

• It helps the body maintain a constant internal environment. 

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Many fish and aquatic plants can survive a cold winter because the layer of ice that forms at the top of a lake insulates the water below and prevents the lake from freezing solid. What unique property of water contributes to this effect? 

• Water absorbs heat when it evaporates and forms a gas. 

• Water expands and becomes less dense when it freezes. 

• Water molecules completely separate into ions in solution. 

• Water forms hydrogen bonds with ions and other polar substances. 

   

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Water has several properties that make it essential to life as we know it. Which property of water is the most important for delivering nutrients to cells in the human body?  

• High specific heat 

• Expansion upon freezing 

• Ability to dissolve many substances 

• Cohesive behavior 

All living things need to transport molecules from one place to another in order to carry out necessary life functions. Living things often transport these molecules by dissolving or dissociating them in water and then moving the resulting solutions from place to place. What characteristic must a molecule have for it to form a solution in water? 

• It must be at least as small as the polar water molecules. 

• It must be nonpolar to be able to react with the polar molecules. 

• It must be at least slightly polar to be able to react with the polar water molecules. 

• It must be covalently bonded in order to form new bonds with the polar molecules. 

Once ice forms on a lake in winter, the water underneath the ice remains about 4'C, even in the air temperature just above the ice is far below freezing. What property of water helps keep the water below the ice from freezing?

• When covalent bonds form between the water molecules in ice, they give off heat

• Each water molecule stores heat in its covalent bonds during the summer and releases it slowly over the winter

• The hydrogen bonds that form in the ice create a lattice structure, and the resulting extra space enables the ice to act as insulation

• The unstable hydrogen bonds between water molecules break and push the molecules around, which keeps the water from freezing

Temperatures around large bodies of water tend to be more moderate than temperatures inland. What properties of water accounts for this? 

• Water has low salinity. 

• Water has a higher density than solvents. 

• Water has the ability to absorb, store, and release large amounts of thermal energy. 

• Water has polar properties that cause cohesion among individual water molecules. 

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