Water and the Fitness of the Environment

Water and the Fitness of the Environment

The Polarity of Water Molecules result in Hydrogen Bonding

A polar molecule is a molecule in which there is unequal distribution of electrons.

Example of polar molecule is water. In water the electrons spend more time near oxygen that hydrogen, which results in hydrogen possessing a positive charge and oxygen possessing a negative charge. Hydrogen atoms in water attracts the nearby oxygen which possess a negative charge and vice versa. This forms hydrogen bonding.

Polar molecules are like a magnet which has north and south pole.

Four Emergent Properties of Water contribute to Earth’s Fitness for Life

Cohesion, Adhesion, Surface Tension, Moderation of temperature and Insulation of Bodies of Water by Floating Ice

Cohesion is a phenomenon in which same substance are held together by hydrogen bonds. Adhesion is the ability of different substance to cling together. Surface tension is the measure of how difficult it is to stretch or break the surface of a liquid. Heat is a form of energy. Temperature is the measure of heat intensity due to the average kinetic energy, energy of motion, of molecules in a body of matter. Kilocalorie is the amount of heat required to raise the temperature of 1 kg of water by 1°C Water absorbs the heat from the warm air and release the heat to the cool air, with only a slight change in its own temperature. This ability of water stems from high specific heat of water which is the amount of heat that must be absorbed or lost for 1g of a substance to change its temperature by 1°C . Hydrogen bonds are strong as a result water has high specific heat. Heat of vaporization is the quantity of heat that must be absorb for 1g of a substance to be converted from liquid to gaseous state. Water has a relatively high heat of vaporization. Another phenomenon of water is known as evaporative cooling in which when water evaporates the surface of the water that remains behind cools. Water reaches its greatest density at 4 degrees Celsius and at 0 degree Celsius it expands.

An example of cohesion and adhesion is seen in plants. In plants, cohesion holds the water column together, adhesion helps the water cling to the vessel walls in the plants, while evaporation helps pull the water upward.

Evaporative cooling is like an automatic AC that turns on whenever the temperature gets hot in order to cool the room.

The Solvent of Life

A solution is a liquid that is a homogenous mixture. The dissolving agent of a solution is a solvent and the dissolved agent is called a solute. In a solution, the solute is broken down to the ionic or molecular level. If an ionic crystal is dissolved in water, it breaks down into positive and negative ions which attract the water’s negative and positive region forming hydrogen bonds. The surrounding water molecules shield the positive and negative ions from one another forming a hydration shell. Any substance that has an affinity for water is hydrophilic, while substances that repel water is hydrophobic. Colloid particles are hydrophilic substance that suspend in liquid. Chemical reactions depend on collisions of molecules and therefore on the concentrations of solutes in aqueous solution. One mole of a substance contains 6.02 x 1023 atoms or molecules. The mass of one mole of a substance is equal to the atomic mass of the atom or molecule of that substance. Molarity is the number of moles of solute per liter of solution.

Example of hydrophobic substances include nonionic and nonpolar. Ex: Carbon dioxide.

Moles are like dozen. They both measure a particular