AP Biology: Properties of Water

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By

​Properties of Water

​Notes:
Polarity

​Notes: Cohesion, Surface Tension, and Adhesion

​Notes:
Temperature
Control

​Notes:
Low Density
Of A
Solid

​Notes:
Excellent Solvent

​Notes: pH and Buffers

Multiple Choice

In a single molecule of water, two hydrogen atoms are bonded to a single oxygen atom by

• hydrogen bonds.

• nonpolar covalent bonds

• polar covalent bonds.

• ionic bonds.

• van der Waals interactions

Multiple Choice

The slight negative charge at one end of one water molecule is attracted to the slight positive charge of another water molecule. What is this attraction called?

• a covalent bond

• a hydrogen bond

• an ionic bond

• a hydrophilic bond

• a hydrophobic bond

Multiple Choice

Which of the following effects is produced by the high surface tension of water?

• Lakes don't freeze solid in winter, despite low temperatures.

• A water strider can walk across the surface of a small pond.

• Organisms resist temperature changes, although they give off heat due to chemical reactions.

• Water can act as a solvent.

• The pH of water remains exactly neutral

Multiple Choice

The bonds that are broken when water vaporizes are

• ionic bonds.

• hydrogen bonds between water molecules.

• covalent bonds between atoms within water molecules.

• polar covalent bonds.

• nonpolar covalent bonds

Multiple Choice

Many mammals control their body temperature by sweating. Which property of water is most directly responsible for the ability of sweat to lower body temperature?

• water's change in density when it condenses

• water's ability to dissolve molecules in the air

• the release of heat by the formation of hydrogen bonds

• the absorption of heat by the breaking of hydrogen bonds

• water's high surface tension

Multiple Choice

Which of the following statements is true about buffer solutions?

• They maintain a constant pH when bases are added to them but not when acids are added to them.

• They maintain a constant pH when acids are added to them but not when bases are added to them.

• They maintain a constant pH of exactly 7 in all living cells and biological fluids

• They maintain a relatively constant pH when either acids or bases are added to them.

• They are found only in living systems and biological fluids.

Multiple Choice

Hydrophobic substances such as vegetable oil are

• nonpolar substances that repel water molecules.

• nonpolar substances that have an attraction for water molecules

• polar substances that repel water molecules

• ar substances that have an affinity for water.

• charged molecules that hydrogen-bond with water molecules.

Multiple Choice

Why does ice float in liquid water?

• The liquid water molecules have more kinetic energy and thus support the ice.

• The ionic bonds between the molecules in ice prevent the ice from sinking.

• Ice always has air bubbles that keep it afloat.

• Hydrogen bonds stabilize and keep the molecules of ice farther apart than the water molecules of liquid water

• The crystalline lattice of ice causes it to be denser than liquid water

Multiple Choice

Some insects can stand on the surface of calm water. Their feet push the surface of the water down slightly, but they do not break the surface. Why?

• The insects are light enough so 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
  

Multiple Choice

 Many fish and aquatic plants can survive a cold winter because the layer of ice that forms at the top of the 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 solutions.
•  Water forms hydrogen bonds with ions and other polar substances. 

Multiple Choice

Water is an excellent solvent. Select the property that justifies this statement.

• as a polar molecule, it can surround and dissolve ionic and polar molecules

• it forms ionic bonds with ions, hydrogen bonds with polar molecules, and hydrophobic interactions with non polar molecules

• it forms hydrogen bonds with itself so cohesion is possible

• it is liquid and will adhere to many substances

Multiple Choice

Water has a much higher specific heat than most other covalent compounds. What do you predict might happen if water had a low specific heat instead?

• Flooding would occur and animals would be forced to migrate
•  Harmful organisms living in water would reproduce at a rapid rate
• Organisms that are sensitive to changes in temperature would die
• Plants would not have enough water to effectively carry out photosynthesis