Basic Chemistry Essasy - Properties of Water

One property of water that makes life possible on earth is its solid state, (frozen).Water is less dense as a solid than it is as a liquid, which enables ice to float. When its temperature falls below 4 degrees Celsius, the molecules slow down to a point where they are not moving fast enough in order to break the hydrogen bonds, therefore making the bonds more stable. The bonds then are farther apart, making the solid less dense. Water is one of the few molecules that has this property, allowing aquatic life to survive cold winters. If ice sank to the bottom of large bodies of water, this would allow all bodies of water to freeze solid. Animals would not be able to live underneath the water during cold months, which is why the density of water in a solid state is a key factor to the functioning of living organisms.

Water molecules stick together as a result of hydrogen bonding. These hydrogen bonds in water are very unstable, and are constantly breaking and re-forming, meaning that at any second, most of the molecules are bonded to the molecules next to them. The property of water molecules being held together is called cohesion. Cohesion plays a large role in the transportation of water against gravity in plants. Hydrogen bonds cause water molecules leaving the veins of plants to hold on to molecules that are farther down in the vessels of the plant. This pull is transmitted all the way down to the roots. Because of this, when water is evaporated from cells in plant leaves, it is able to be replaced with water transported from the roots, thus the survival of the plants.

Another unique property of water is its surface tension. Surface tension is the measure of how difficult it is to stretch or break the surface of a liquid. Water's surface tension is greater than most other liquids. The strengths of the hydrogen bonds at the surface of the water keep the upper molecules bonded together, as well as keeping these molecules bonded to those below them. These tightly packed molecules act as a "film" on top of the water. This allows various insects and animals to "walk" on the surface of water. Without the surface tension, these organisms, such as the water strider, would be extinct, or non-existent in the first place. Surface tension or water is a key ingredient in the survival of many insects.

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