Four emergent properties of water were discussed during lect

Four emergent properties of water were discussed during lecture. What are they? How do they contribute to the Earth\'s suitability for life? Cohesive behavior: Ability to moderate temp: Expansion upon freezing; Versatility as a solvent:

Solution

Answer:

1. Cohesive behaviour: When hydrogen bonds hold the substance together. Water molecules are linked together by multiple hydrogen bonds, which makes water more structured than most liquids. Cohesion, due to hydrogen bonding, contributes to the transport of water and dissolved nutrients against gravity in plants. Water has an unusually high surface tension because the interface between water and air is an ordered arrangememt of hydrogen bonds and the surface of the water.

2. Ability to moderate temperatures: A brief explanation of kinetic energy is important to the topic of moderation of temperature. Kinetic energy is the energy of motion. In a body of water the molecules of water are always moving. This movement of the molecules is kinetic energy. Heat is the measure of a substance’s kinetic energy as a result of the movement of its molecules. If you add up all the kinetic energy of all the molecules in a body of water you get the heat of that body. This means that heat is determined by volume unlike temperature which just states the obvious regardless of volume. Taking this all into account large bodies of water like the Pacific Ocean have lot of heat.

3. Expansion upon freezing: When water freezes it becomes less dense than it is at its liquid form. This is important to prevent a runaway freezing effect on bodies of water. If water was more dense in solid form it would freeze at the surface and then sink to the bottom. This process repeated would consume all of the bodies of water with ice. Life in an ocean of solid ice would be difficult. However, frozen water is less dense than the liquid form, therefore it floats. Floating ice on bodies of water provide the additional benefit of insulation. The ice layer on the surface insulates the heat of the water below allowing for suitable water temperatures for life.

4. Versatality as a solvent: The polarity of the water molecules make water a great solvent. Ionic compounds can be dissolved in water because of the negative charge of the oxygen atom and the positive charge of the hydrogen atoms. The water molecules surround the oppositely charged ions as a result of attraction to their polar charges. The water molecules create a hydration shell that separates the ions and the compound is dissolved. There are other nonionic polar molecules that can be dissolved in water. Water, as a solvent, is the essential substance in nearly all life functions.