2.2 - B - Properties of Water
The hydrogen bonds that form between water molecules result in it having cohesive properties. Cohesion refers to the molecules of the same type binding together.
This is useful for plants as water can be sucked through the xylem at low pressure because the molecules 'pull' each other.
Hydrogen bonds can also form between water and other polar molecules, which is called adhesion. This also aids in the transport of water in plants as the water adheres to the cellulose found in the cell wall of the plant cells.
Adhesive & Cohesive Properties
Water is an important solvent in organisms because of its polar nature. It forms 'shells' around charged and polar molecules, which dissolves them and prevents them from clumping together. Water forms hydrogen bonds with polar molecules.
The cytoplasm inside cells is a complex mixture of dissolved substances in which the chemical reactions of metabolism occur. If they were not able to dissolve in the water, these reactions would not take place.
Due to the hydrogen bonds that form between polar molecules, water has a high latent heat of vaporization which is the energy needed for it to evaporate. When sweat is released by the sweat glands, it spreads across the skin and absorbs heat from the surrounding tissues When the water evaporates, it carries this heat away from the body, cooling it overall.
Sweat secretion is controlled by the hypothalamus in the brain, which has thermoreceptors that monitor blood temperature.
Water also has a high specific heat capacity, which results from hydrogen bonds restricting the motion of the molecules. This means that more energy is required to raise the overall temperature.. In order to raise or lower the temperature of water, a great deal of water must be put in or lost.
This property is particularly useful for aquatic organisms as it results in their habitat remaining fairly stable in changing weather conditions.
Water vs. Methane
Methane is a waste product of anaerobic respiration in certain prokaryotes that live where oxygen is absent. Like water, it is small molecule linked by single covalent bonds. However, unlike water, methane molecules are not polar and thus do not form hydrogen bonds.
Notable difference in thermal properties include:
Crash Course: Water Liquid Awesome
The following video reviews the atomic structure of water molecules and properties that result from the hydrogen bonds that they can form. As you go through it, add to your notes any relevant information