Water. Characteristics of water - Essay Example

?Introduction Water is the most abundant compound on an earth, occupying an approximately 75% of the total surface. It has unique chemical and physical properties that facilitate its wide application in natural and artificial processes. Water is one of the major life-sustaining components that play a critical role in maintaining biological processes in the body of all organisms. According to Benjamin (32) water comprises of about 54-78% of the total human body. It is an important component of human nutrition and it is taken directly through drinking and as a constituent of food. This paper examines scientific and chemical properties of water, with special focus on its application in food and nutrition. Characteristics of water Water has a chemical formula, H2O and hence it is a compound made of one oxygen and two hydrogen atoms, bound by strong covalent bonds. Water naturally exists in three states, namely solid in form of ice, liquid and in gaseous form. In liquid state, chemically pure water is tasteless, odorless and colorless substance with a tinge of blue color. It has a density of 1g/cm3 at 40C . Water freezes at 0o C and reaches its boiling point of 100oC at standard pressure of 760mm Hg (Benjamin 53-56). Water demonstrates various chemical properties. It reacts with acidic and basic oxides forming inorganic acids and alkalis respectively. Water reacts with metals and non-metals to form respective hydroxides (Armstrong and Kellee, 19). Some salts bonds with water to form hydrated compounds containing water of crystallization in the structure. These hydrated salts can loose the water of crystallization when subjected to high temperature forming anhydrous compounds. Water is a polar molecule and many substances dissolves in it (Benjamin76). The chemical and physical properties of water are based on its structure. Water comprises of two hydrogen atoms and one oxygen atom. The two hydrogen atoms are bonded by strong covalent bonds to the oxygen atom through shared pair of electrons. These strong covalent bonds make water molecule one of the most stable compounds, very difficult to decompose into its constituent atoms. Both oxygen and hydrogen atoms have different capacities to attract electrons. Oxygen atom is more electronegative than hydrogen atoms and therefore it attracts more negative charges on its end, leaving the two hydrogen ends partially positively charged. This creates a dipole moment on the structure and therefore, water is a polar molecule because of unequal sharing of electrons in its structure (Armstrong and Kellee, pp 108-114). Fig 1: Structure of water molecule (Armstrong and Kellee, 110) This creates a tetrahedral structure, where H-O-H angle is about 105o as shown in the figure 1. Although atoms in the water molecule structure are linked by strong covalent bonds, the resulting bonds between water molecules are linked by hydrogen bonds. Hydrogen bonds are weaker than covalent bonds (Benjamin 159). Therefore, water has relatively low boiling point because of the weak hydrogenbonds. The hydrogen bonds results from attraction of partial positive charges between hydrogen and oxygen atoms of different water molecules. The hydrogen bonds play a critical role in determining the physical and chemical properties of water. Due to dipole structure on the water molecule, it readily dissolves ionic or charged molecules and therefore water is regarded as universal solvent (Tortora et al 69) Natural occurring water contains many dissolved substances that affect its physical and chemical properties. Hard water contains dissolved minerals and should be softened to enhance its quality. High concentration of calcium and magnesium ions causes water hardness. Pure water is neutral but acidic and basic substances dissolve in water altering the pH. Acidic substances reduce the pH of water while basic substances increase the pH. Hydrogen bonds create strong cohesion forces on water surface. According to MWH (72), the unusual chemical and physical properties of water such as high surface tension, specific heat and heat of vaporization are caused by the hydrogen bonds. Food contains different substances, including sugars, organic acids, minerals, carbohydrates, proteins, fats and oils, vitamins and water in various proportions. Water is a major component of all foods and its concentration differs depending on the type of food. Foods such as fresh fruits, vegetables and meat contain higher proportion of water than dried foods. According to Bruce and Perry (38), the amount of water in food in divided into two categories. One category comprises of water that is chemically combined with the various nutrients such as sugars and amino acids. This type of water is nor available for other chemical processes and microbial growth in the food. The second category of water in food is not chemically bound and therefore it is available for microbial growth and other chemical processes in food (Bruce and Perry, 46) Therefore, free water is responsible for food spoilage because it initiates growth of microorganism and other chemical reactions. Water acts on food through several processes. These processes include dehydration, hydrolysis and hydration. In hydrolytic reactions, water combines with large molecules in water to form smaller molecules (Armstrong and Kellee, 77). For example, maltose, which is a disaccharide, can undergo hydrolytic reaction in presence of water to produce glucose. In living organisms, hydrolytic reactions occur in presence of enzymes. C12H22O11 + H2O>C6H12O6 + C6H12O6 Similarly, reaction of water with dipeptides in presence of the appropriate enzymes produces amino acids, the basic units of proteins. When water is added to food containing organic acids, hydrolytic reaction occurs resulting to formation of acidic medium as shown below (Armstrong and Kellee, 85). RCOOH + H2O> RCOO- + H+ Dehydration is the second important mechanism of water on food. Dehydration is a chemical process in foods that entails combination of two or more simple molecules to produce a large complex molecule and water. Simple amino acids can combine with other amino acids in presence of suitable enzymes to produce a dipeptide and water molecule. In biochemical reactions, hydration entails the addition of water molecule to a substituent organic group to produce a hydroxyl group. In biochemistry, most hydration reactions produce alcohol in the process of fermentation (Benjamin pp99-105). . From the above chemical reactions, it is apparent that water affects the quality of food in two mechanisms. In the first mechanism, water initiates chemical reactions between components in the food, resulting to formation of different compounds. In the second mechanism, water stimulates the growth of microorganisms on food substrate. Water stimulates the growth of microorganism on food by dissolving the nutrients, which enables easier absorption by bacterial, fungi, and other microorganisms that cause food spoilage. In addition, water activates enzymes present in food and microorganism. The enzymes initiate chemical reactions that alter chemical composition of food (Raven and Johnson, 97-99) Water plays an important role in the body of all living organisms. It is used as a medium of transporting nutrients and other important minerals in the body. Because of its polarity, water dissolves and transports many compounds to targeted organs for various processes such digestion and excretion. All cells in the body require water to maintain turgidity and for optimum performance (Madigan, et al 117). In both plants and animals, water is important for regulating temperature. Water has high latent heat of vaporization that enables the body of an organism to cool as it evaporates from the surface. In addition, water plays an important role in excretion and removal of toxic substances from the body of organisms. In human body, water removes toxic substances through urination, bowel movements and sweating (Raven and Johnson pp123-130). Lack of water in the body affects various physiological processes profoundly and it could easily result to death. Some of the systems that are greatly affected by dehydration in the body include digestion, blood circulation and excretion. Lack of water causes poor digestion and absorption of nutrients in the body (Madigan, et al 143). It alters the osmotic balance, resulting to interference of important cellular processes such as osmosis and diffusion in the body. Consequently, transport of nutrients, oxygen and waste products is affected. When there is insufficient water in the body, the liver and the kidneys, which are major organs for detoxifying and removal of waste products, are overworked (Bruce and Perry 220). Lack of water in the body and drinking poorly treated water is hazardous to human health. Pathogenic microbes such as bacteria, viruses and fungi are easily transmitted in water. The microorganisms cause some of the most severe waterborne diseases, including cholera and typhoid that cause extreme dehydration in the body (Madigan et al, 87). Addition of excess fluorine compounds to drinking water is the leading cause of dental and skeletal flourosis in the world. Excess accumulation of water in body tissues is also hazardous and it interferes with concentration of ions in the body. Hyponatremia is a condition that results from extreme dilution of sodium ions in the body fluids because of excess accumulation of water (MWH, 154). To ensure that people access quality drinking water, global and national health organizations have established standards for ensuring access to enough and healthy water. To ensure that people have access to clean water, it is compulsory for raw water to undergo treatment processes in order to kill harmful microorganisms and remove excess fluorine (Benjamin 164). Currently there is no economically viable process of manufacturing water and people rely on natural sources. However, in the laboratory, water is manufactured in a controlled experiment that involves burning of hydrogen gas in presence of oxygen. In typical water processing plants, water is obtained from natural sources and passed through treatment process to remove microorganisms and other harmful contaminants. Conclusion Water is an essential commodity for sustaining life and it is important to supply people with enough and clean water to maintain health. Water shortage in the body undermines the normal functioning of the organs, cells, tissues and organ systems resulting to diseases. Excess fluorine in drinking water weakens the teeth and skeletal structure while presence of pathogenic microorganisms causes waterborne infections. To ensure that people have access to clean and enough water, it is important to implement appropriate water treatment procedures and enhance distribution channels to all people. Work Cited Armstrong, J., and Kellee, H. General, Organic and Biochemistry. An applied Approach. New York: Cengage Learning, 2010. Benjamin, M. Water Chemistry. London: McGraw Hill science, 2001. Bruce, R. and Perry, M. Environmental Biotechnology: Principles and Applications. New York: McGraw Hill Science, 2000. Madigan, M., et al. Brock Biology of Microorganisms. 12 ed. Chicago: Benjamin Cummings, 2008. MWH. Water Treatment : Principles and Design. 2nd ed. London: Wiley, 2005 Raven, P., and Johnson, G. Biology: Updated version. 3rd ed. Dubuque, Iowa: Brown publishers, 1995. Tortora, G., et al. Microbiology: An introduction. 5th ed. Red wood city, CA: Benjamin& Cummings Publishing, 1995. . Read More