Water H2O Summary
Water is the most important chemical compound known to man. Water covers 70% of the earth found mostly in oceans and lakes. It is very important to humans. Water contains 83% of your blood, 90% of your lungs, 75% of your brain, and 22% of your bones. Overall water covers 50-60% of your body. Humans can live 5-7 days without water. When you're dehydrated you are usually about 5-7% low on water. If water was not consumed on a daily basis, humans would be an extinctive race. Water is a chemical substance that is composed of hydrogen and oxygen and is essential for all known forms of life. Water refreshes us while also governing the weather. Water also is incredibly versatile, dissolving many substances and delaying others.
Water is known as the universal solvent. A solvent is a substance capable of dissolving other substances. Solutes are those substances that dissolve in a solvent. The result is called a solution. Aqueous solutions are solutions in which water is the solvent. So where does drinking water exactly come from? H20 is found in oceans, lakes, rivers, snow, and glaciers on the service. Underground water is found in aquifers, which are pools of water trapped in sand and gravel 50-500 feet below the surface. Water that can be made for drinking comes from either surface water or groundwater. Surface water is water from lake, rivers, and reservoirs. Groundwater is water pumped from wells that have been drilled into underground aquifers. Groundwater takes less to purify as opposed to surface water that contains substances that must be removed before it can be used as drinking water. For the distribution of water, only 2.59% of water comes from freshwater. Of that 2.59% of freshwater, .014% of it comes from lakes, rivers, atmosphere, and soil moisture. The rest comes from ice caps, glaciers, and groundwater. The world's drinking water supplies are very limited. In the US, 80% of the fresh water is used to irrigate crops and to cool electrical power plants. Because water is a solvent, drinking water is never pure water. It contains other substances which municipal water companies provide information about the dissolved mineral content, the solutes, for tap water. Some of the mineral composition for tap water include; calcium, magnesium, sodium, sulfates, chlorides, nitrates, and fluorides.
Water has three physical properties and a very unique physical structure. Water appears in nature in three common states of matter; a solid, liquid and a gas. Water appears in nature in all three common states of matter and may take many different forms on Earth. Water vapor and clouds in the sky, seawater and icebergs in the oceans, and glaciers and rivers in the mountains; and the liquid in aquifers in the ground. The water cycle describes the continuous movement of water on, above, and below, the surface of the Earth. Since the water cycle is a "cycle," there is no beginning or end. Water can change states among ice, vapor, and liquid at different places in the water cycle. Although the balance of water on earth remains constant over time, individual water molecules come and go. In liquid form, water is tasteless and odorless at standard temperature and pressure. The color of water and ice is a light blue hue, although water appears colorless in small qualities. Ice is also colorless and water vapor is invisible as a gas. The solid state of most things is much denser than the liquid state and ultimately does sink. Usually what happens when a solid is formed is the molecules become tightly packed together. When things melt, the molecules move apart resulting in liquid. But water is different- the solid state is less dense than the liquid. To understand, a close-up look at the molecular arrangement of solid water (ice) and liquid water must be done. Liquid water also has surface tension. Surface tension helps things like spiders walk on water. The force of surface tension balances the spider's weight, helping it to walk on water. Surface tension affects the top layer of water, causing it to behave like a stretched elastic sheet. It occurs because the attraction between water molecules is not balanced at the liquid surface. Away from the surface, H2O molecules are pulled equally in all directions by neighbors, but those in the top layer are not. Along with surface tension water also has a specific heat. Specific heat is the energy required to raise the temp of 1g of substance by 1*C. H2O has high specific heat and needs a large quantity of energy to raise the temp. Water is the chemical substance with formula H2O: one molecule of water has two hydrogen atoms covalently bonded to a single oxygen atom. The water molecule is not linear and the oxygen atom has a higher electronegativity then hydrogen atoms, so it carries a negative charge. . Water is also transparent to the human eye. Water as a liquid has a boiling point of 100*C and a freezing point of 0*C. Electronegativity is a measure of an atom's attraction for the electrons it shares in a covalent bond. The hydrogen atoms are positive, resulting in a polar molecule with a dipole effect. Because of the electronegativity difference, the shared elections are pulled closer to the more electronegative oxygen and away from the less electronegative hydrogen. This unequal sharing gives the oxygen end of the O-to-H bond a partial negative charge and the hydrogen end a partial positive charge. The result is polar covalent, which is a covalent bond in which the electrons are not equally shared, but displaced toward the more electronegative atom. Since H2O has polar covalent bonds, this can help understand some of the unusual properties of water. A water molecule can form a maximum of four hydrogen bonds because it can accept two and donate two hydrogen atoms. H2O has a unique molecular structure. The O-H bond lengths are 0.096 nm and the H-O-H angle = 104.5*. There are six valance electrons on oxygen, and one each from the hydrogen atom in the water molecule. The eight electrons form two H-O bonds, and left two pairs. The long pairs and bonds stay away from each other and they extend towards the corners of a tetrahedron. Such a structure should give H-O-H bond angle of 109.5*, but the alone pairs repel each other more than they repel the O-H bonds. Therefore the O-H bonds are pushed closer, making the H-O-H angle less than 109°. As for the quantum mechanics, the electronic configuration for the valence electron of oxygen are 2s2 2p4. Triatomic molecules such as water, molecular orbital (MO) approach can be applied to bonding. The results are similar to the valence bond, but the MO theory gives all the energy levels of the electron for more exploration. Water molecules are very symmetric. If the molecules are rotated 180* the shape of the molecule is untroubled. This is showing that the molecules have a 2 fold rotation axis.
Molecules like hydrogen fluoride, ammonia, and methanol form hydrogen bonds but they do not show behavior of kinetic or structural properties like properties of those experiented in water. The difference between water and other hydrogen bonding liquids are that apart from water, none of the hydrogen bonding molecules can form four hydrogen bonds due to an inability to donate or accept hydrogen's or due to effects in bulky residues. In water, local tetrahedral order because of the the four hydrogen bonds gives rise to an open structure and a 3-dimensional bonding network, resulting in the decrease of density when cooled below 4*C. Hydrogen bonding is a weak attraction compared to the covalent bonds within the water molecule itself, it is responsible for a number of water's physical properties. One property is the very high melting and boiling point temperatures, because more energy is required to break the hydrogen bonds between molecules. The similar compound hydrogen sulfide (H2S), which has much weaker hydrogen bonding, is a gas at room temperature even though it has twice the molar mass of water. The numerous extra bonding between water molecules gives liquid water a large heat capacity. This very high heat capacity makes water a good heat storage medium (coolant) and heat shield.
Since water is not a renewable source, much is happening to try and save the water from running out. Also, much is happening to keep the water safe and drinkable. What dissolves in drinking water determines its quality and the potential for adverse health effects. Keeping public water supplies save has been recognized as a very important public health issue. In 1974, congress passd the Safe Drinking Water Act. The SDWA amended the act in 1996 to ensure that each water supplier delivers a report once a year to consumers from any community water system. These reports study the chemistry of the water and the standards of quality that must be met. Also in the Safe Water Drinking Act, more deferral legislation also controls pollution of surface waters, like rivers, coastal areas, and lakes. The Clean Water Act passed by Congress in 1972 made the foundation for progress by reducing surface water pollution over the past three decades. The first step in a drinking water treatment plant is to pass the water through a screen that excludes larger objects such as but not limited to fish, sticks, and tires. The next step is to add Aluminum Sulfate, Al2(SO4)3, and calcium hydroxide, CaOH2. These are called flocculating agents and react to form a sticky gel of aluminum hydroxide, Al(OH)3. The gel settles which slowly carries the suspended particles down a settling tank. Remaining particles are removed as the water is filtered through coal or gravel and then sand. The filtered water is then pumped to the next step to disinfect and to kill organisms that could ultimately kill disease. Chlorine is usually added in one if the three forms: Cholorine gas, Cl2; sodium hypochlorite, NaCIO; or Calcium Chlorite, Ca(CIO)2. The antibactrial generated in the three solutions can is hypochlous acid, HCIO. Another way to disinfect water that is gaining popularity is the use of ultraviolet radiation. The last step to water purification is the spraying of water into the air to remove volatile chemicals that create objectible odors and tastes.
Is bottled water really better than tap water? Water has always been very essential to our body's system and survival, lately; it has become a huge fitness craze to drink bottled water. Although people used to largely rely upon tap water, in the last two decades, consumers have begun to break away from this source due to public health scares like the 1993 Milwaukee outbreak that infected more the 400,000 city residents. In their marketing strategies, bottles water companies promised for a purer, healthier, water product then tap water. Which has expanded greatly for supply growing demands for quality drinking water. According to “The Truth about Bottled Water”, in the year 2003, Americans alone spent more than $7 billion on bottled water at an average cost of more than $1 a bottle. It is easy to see that the bottled water industry is here to stay, but the price is very expensive. Recent allegations for the Coca- Cola Company and its brand name bottled water, Dasani have been publicly scrutinized for being on of the biggest fallacy about the quality of bottled water. As advertised, Coca- Cola marketed as “pure, still water”, but is now being investigated for miusleading consumers about the natural contents of its bottles. Dasini stated their water came from natural springs but really Coca- Cola had actually been filling its bottles with purified tap water. Unfortunately, the process of bottling tap water is not limited to the Coke Company. Researchers from the National Resources Defense Council (NRDC) published the results of a four- year study in which they sampled 1000 bottles of 103 brands of bottled water. They found that 25% of more of bottled water is really just tap water in a bottle. Also in a recent study conducted by Showtime television, the hosts found the 75% of tested New York City residents actually preferred tap water over bottled water in a blind taste test. Also, while municipal water systems must test for harmful microbiological content in water several times a day, bottled water systems are required for these tests only once a week. Public water systems are required to test for chemical water contaminants four times as often as bottled water companies. And loopholes in the FDA's testing policy do not require the same standards for water that is bottled and sold in the same state, defining that a great amount of bottles have undergone almost no regulation or testing. Even under the more strict levels of the FDA, Bottled water companies do not always comply with standardized contaminant. About one fift of the brands tested positive for the presence of synthetic chemicals and chemicals used in manufacturing plastic, like phythalate, a harmful chemical that reaches into bottled water from its plastic container. Also, bottled water companies are not required to test for chyptosporidium, the chlorine- resistant protozone that infected the 400,000 Milwaukee residents in 1993. Bottled water companies are not under the accountability standards as municipal water systems so the companies may provide lower quality of water then the water one typically receives from the tap.
Waste management has also become a large problem in the world. Growing landfills and enormous sizes of plastic are found in the landfills. The number of plastic bottles produced by the bottled water companies and the number of people buying water bottles has only made this problem worse. In a 2001 report of the World Wide Fund for Nature, roughly 1.5 million tons of plastic are expanded into bottling of 89 billion liters of water each year. Also, the energy required to manufacture and transport these bottles severely drains the limited fossil fuels. Bottled water mentioned by severaly facters, is very much so not a healthier or purer alternative to tap water, and the bottled water companies and industries cause a severe strain on the environment. But also the concerns over the quality and safety of tap water also are is what sparked the growth of the bottled water industry and is still entirely present. This is being helped by water filters and purifiers, the most recent solution to the problems. Filters currently provide the best and most healthy solution to the bottled and tap water problems. Filters remove dangerous contaminates better than any other purification method. And they are uniquely designed to work with municipally treated water. Because filters use no less energy than is already used for what is required to propel water through a plumbing system. So they whole point is that bottled water is not as healthy and environmentally safe as tap water.
H2O has many chemical uses. It is widely used in chemical reactions as a solvent and less used as a reactant. But more than that, less used as a solute or catalyst. In inorganic reations, it is uncommonly used as a reaction solvent because it does not dissolve the reactants well. Also these properties are sometimes desirable. Water and steam are used as both heat transfer fluids in diverse heat exchange systems also due to high heat capacity, both as a coolant for heating. Cool water is actually available from the lake or the sea. Steam is available in its natural state in clouds. A disadvantage is that water and steam are somewhat corrosive, but are used as heat transfer in diverse heat exchange systems. In most of the power stations, water is the coolant, which does vaporize and drives steam turbines to drive generators. In the U.S, cooling power plants is the largest use of water.
Another good use of water is used to extinguish fires. Water has a very high heat of vaporization and is pretty inert, which makes a pretty good fire. The evaporation of water carries heat away from the fire. However it is hard for water to fight fires of electric equipment because of impure water which is an electrically conductive of oils and organic solvents, because thy float on water and the explosive boiling of water spreads through burning liquid. Another use for water is irrigation. It is estimated that about 69% of the worldwide water is for irrigation. About 20% of irrigation is being called unsustainable. It is necessary to grow crops with irrigation in some parts of the world. But in other areas it is more profitable to grow crops that are between crop yields. Some of the irrigation methods include a furrow and overhead sprinkler, which are usually less expensive but less efficient, because much of the water evaporates and runs off and drains below the root zone. Some irrigation methods that are more efficient include drip and trickle irrigation, and surge irrigation. Some types of sprinkler systems were the sprinklers are operated near ground level. These methods are more expensive but usually offer more potential to minimize runoff and evaporation. Systems that are not managed properly can be very very wasteful.
As seen, water is the most important chemical compound known to man. Without water, nobody would be here. Water takes up about 75% of the human body Water needs to be potable which is fixed for human consumption usually a high mineral content. Also Water needs to be clean and fresh. Access to safe drinking water has steadily improved and substantially in the last decades in almost the whole parts of the world. However, it's estimated that by 2025 more than half of the world population will be facing water- based shortages. Everything possible must be done to fix this water shortage. Even if it comes to cutting down on things like irrigation or household water use. Water is not a renewable resource. Action is already been taken to help out but we must maintain and keep the water from drying up in the world.