Which of the following is responsible for the cohesive property of water?
a. Hydrogen bonds between the oxygen atoms of two adjacent water molecules
b. Covalent bonds between the hydrogen atoms of two adjacent water molecules
c. Hydrogen bonds between the oxygen atom on one of water molecule and a hydrogen atom of another water molecule.
D. Hydrogen bonds between water molecules and other types of molecules
*e. Covalent bonds between the oxygen atom on one water molecule and a hydrogen atom of another water molecule
the answer is c
Water molecules stay close to each other (cohesion), due to the collective action of hydrogen bonds between water molecules. These hydrogen bonds are constantly breaking, with new bonds being formed with different water molecules; but at any given time in a sample of liquid water, a large portion of the molecules are held together by such bonds.
Water also has high adhesion properties because of its polar nature. On extremely clean/smooth glass the water may form a thin film because the molecular forces between glass and water molecules (adhesive forces) are stronger than the cohesive forces. In biological cells and organelles, water is in contact with membrane and protein surfaces that are hydrophilic; that is, surfaces that have a strong attraction to water. Irving Langmuir observed a strong repulsive force between hydrophilic surfaces. To dehydrate hydrophilic surfaces—to remove the strongly held layers of water of hydration—requires doing substantial work against these forces, called hydration forces. These forces are very large but decrease rapidly over a nanometer or less. They are important in biology, particularly when cells are dehydrated by exposure to dry atmospheres or to extracellular freezing.