Introduction
Water is a transparent and colorless inorganic substance mainly composed of hydrogen and oxygen (Marques, de Matos Jorge, and Jorge, 2016). According to Marques, water exists in a solid, liquid, and gaseous state, and forms the main component of the earth's hydrosphere. Interestingly, 97% of the water on the earth's surface is salty, and only 3% of the water on the earth's surface is fresh and usable. Quoting Marques, 2% of earth's freshwater is in 'glaciers and caps as solid ice. This means that only 1% of freshwater is available for agricultural, industrial, and household purposes. This academic paper provides a detailed analysis of the chemical characteristics of water and the biological role of each characteristic in sustaining life.
Chemical characteristics of water:
(a) Water as a polar substance
According to Al-Mashagbah (2015), each water molecule is made up of two hydrogen atoms and one oxygen atom held together by covalent bonds. In the formation of this molecule, the oxygen atom has 6 electrons from its outermost electron shell, which are shared in two places with two hydrogen atoms. During sharing, slightly positively charged hydrogen atoms are attracted to the negative oxygen atoms. This attraction leads to the formation of hydrogen bonds. The hydrogen bond in water molecules is the key reason why water has a high boiling point when compared to other chemical substances with the same molecular mass.
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Despite the overall neutral charge of the water molecules, there is a small distribution of both positive and negative charges on the outside of each water molecule. According to Al-Mashagbah (2015), the distribution of these charges is the reason behind the polarity characteristic. Water is a polar substance because it can be attracted to both positive and negative charges in solutes. For example, when water reacts with sodium chloride, the water molecules surround both sodium ions and chloride ions in a process known as solvation. Water being a polar substance will only dissolve polar substances. This means substances that do not ionize in water are non-polar and cannot dissolve in water.
(b) Latent heat of vaporization of water
According to Tanvir, Jain, and Qiao (2015), an increase in temperature within the water molecules lead to an increase in the absorption of heat energy. This rise in temperature leads to a breakdown of hydrogen bonds giving room to the free movement of water molecules. To speed up this movement of molecules, a lot of heat energy is required. For instance, to convert liquid water into vapor, sufficient heat energy must be supplied to increase the movement of water molecules, and to allow the evaporation of water molecules from the surface of liquid water. This high energy requirement in changing from one state to another explains why water has a high latent heat of vaporization.
(c) Cohesive forces of water
The cohesive force of attraction is a liquid property where molecules of the same kind stick together because of mutual attraction (Ji et al., 2015). In solid water, these forces are evident despite the formation of hydrogen bonds at relatively greater distances. Ideally, water molecules intertwine to form six-sided hexagonal shapes. Each oxygen in the water molecule alternate above and below the water molecule ring forming a flat sheet. These flat hexagons extend beyond the plane towards the front and backside, creating a large sheet of hexagons (Ji et al., 2015). This chemical property describes the formation of an open structure, similar to a honeycomb, in ice explaining the reduced density of water in the solid state.
The biological functions of the chemical properties of water:
(a) Water as a polar solvent
Water is the main component in all living organisms and accounts for 75% of total body mass (Tros et al., 2017). Water is involved in almost all biochemical reactions within the living cell. For instance, water is an essential component in the hydrolysis and condensation reactions, which involves the addition and removal of water. Water is also important in photosynthetic light-dependent reactions, which are the main source of energy. As a polar solvent, water can dissolve a wide range of inorganic and biological chemicals into solutions, which can easily be transported within a cell. In particular, the polar character of water is responsible for dissolving sugars, polar molecules, and salt compounds in both plants and animals (Tros et al., 2017). Notably, the hydrogen bonds responsible for water polarity are common in all living organisms. For example, hydrogen bonds are found in DNA, which is responsible for guiding the genetic instructions and the coding of proteins within the cells.
(b) Thermoregulation function of water
High heat capacity is the other chemical property of water (Tros et al., 2017). The heat capacity of water is relatively higher than other substances of similar nature. This quantity of heat is essential in raising the temperature within living cells. According to Tros, the specific heat capacity of water is one calorie per gram. This property makes water resist sudden fluctuations in temperature, which makes water an exceptional habitat for organisms living in an environment that experiences temperature fluxes. Moreover considering that many living cells comprise a relatively higher percentage of water, the high heat capacity of water enables living organisms to regulate their body temperatures effectively. For example, the body temperature of a polar bear is different from the external temperature because the heat capacity of water is used to distribute heat within the body leading to an even body temperature.
(c) Insulation and transport functions of water
According to Al-Mashagbah (2015), hydrogen bonds are responsible for providing water molecules with surface tension and cohesive forces. The cohesive property of water is responsible for the transportation of water in the xylem vessels. Without this property, it would be impossible to transport mineral salts from the soil up to the plant. According to Al-Mashagbah (2015), the cohesive property is also responsible for the surface tension in water. This feature is crucial because it enables insects to walk on water, enabling them to colonize both aquatic and terrestrial habitats. Ice has an unusually lower density when compared to liquid water. This property makes ice float on water-insulating lakes and ponds from low temperatures below 4 degrees Celsius.
Conclusion
Each water molecule is made up of two hydrogen atoms and one oxygen atom held together by hydrogen bonds. Some of the chemical properties of water include the ability to combine with polar substances, high latent heat of vaporization, low density in the solid state, and the ability to form cohesive forces. The biological functions associated with these chemical properties include thermoregulation of body temperatures, insulation against cold temperatures, transportation as well as the ability to dissolve a wide range of chemical compounds. Without a doubt, water is life.
Reference List
- Al-Mashagbah, A., 2015. Assessment of surface water quality of king Abdullah canal, using physicochemical characteristics and water quality index, Jordan. Journal of Water Resource and Protection, 07(04), pp.339-352.
- Ji, K., Rui, X., Li, L., Leblond, A. and McClure, G., 2015. A novel ice-shedding model for overhead power line conductors with the consideration of adhesive/cohesive forces. Computers & Structures, 157, pp.153-164.
- Marques, B., de Matos Jorge, L. and Jorge, R., 2016. Chemical properties and water absorption kinetics of transgenic corn grain (2B587 Hx) and its conventional isoline (2B587). Journal of Cereal Science, 71, pp.93-98.
- Tanvir, S., Jain, S. and Qiao, L., 2015. Latent heat of vaporization of nanofluids: measurements and molecular dynamics simulations. Journal of Applied Physics, 118(1), p.014902.
- Tros, M., Zheng, L., Hunger, J., Bonn, M., Bonn, D., Smits, G. and Woutersen, S., 2017. Picosecond orientational dynamics of water in living cells. Nature Communications, 8(1).
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