Life as we know it could not exist without water. All the chemical reactions of life occur in aqueous solution. Water molecules are polar and are capable of forming hydrogen bonds with other polar or charged molecules. As a result, water has the following properties:
A. H2O molecules are cohesive; they form hydrogen bonds with each other.
B. H2O molecules are adhesive; they form hydrogen bonds with polar surfaces.
C. Water is a liquid at normal physiological (or body) temperatures.
D. Water has a high specific heat.
E. Water has a high heat of vaporization.
F. Water’s greatest density occurs at 4°C.
Explain how these properties of water are related to the phenomena described in parts a-h below. More than one property may be used to explain a given phenomenon.
a. During the winter, air temperatures in the northern United States can remain below 0°C for months; however, the fish and other animals living in the lakes survive.
b. Many substances, for example, salt (NaCl) and sucrose, dissolve quickly in water.
c. When you pour water into a 50-ml graduated cylinder, a meniscus forms at the top of the water column.
d. Sweating and the evaporation of sweat from the body surface help reduce a human’s body temperature.
e. Water drops that fall on a surface tend to form rounded drops or beads.
f. If you touch the edge of a paper towel to a drop of colored water, the water will move up into (or be absorbed by) the towel.