Subject: Water Around Us
Abstract: This paper is the result of the comprehensive practical activities of five of our students, describing the composition and nature of water, categorizing and comparing the water in our lives, and describing their respective uses on this basis. Finally, it analyzes the water pollution situation and its causes in the Zhenjiang section of the Yangtze River Basin and the Ancient Canal Basin, and puts forward a preliminary concept of governance.
Keywords: water, water around us, classification, use, water pollution
Water (H2O) is an inorganic substance composed of two elements, hydrogen and oxygen, and is a colorless, odorless and transparent liquid at room temperature and pressure. Water is one of the most common substances, is an important resource for the survival of all life, including human beings, and is the most important component of living organisms. Water plays an important role in the evolution of life.
1 Properties of Water
1.1 Physical Properties Water is a colorless, odorless, transparent liquid at room temperature and pressure. At 20 ℃, the thermal conductivity of water is 0.006 J/s?6?1cm?6?1K, the thermal conductivity of ice is 0.023 J/s?6?1cm?6?1K, in the density of snow is 0.1 × 103 kg/m3, the thermal conductivity of snow is 0.00029 J/s?6?1cm?6?1K. The density of water is the maximum at 3.98 ℃, 1 × 103 kg/m3, temperature higher than 3.98 kg/m3. m3, the temperature is higher than 3.98 ℃, the density of water decreases with the increase in temperature , in 0 ~ 3.98 ℃, water does not obey the law of thermal expansion and contraction, the density increases with the increase in temperature. Water at 0 ℃, the density of 0.99987 × 103 kg/m3, ice at 0 ℃, the density of 0.9167 × 103 kg/m3. water is a good solvent, most inorganic compounds and a small number of organic compounds can be dissolved in water.
1.2 Chemical Properties
1.2.1 Thermal stability of water. The thermal stability of water is very strong, water vapor heated to more than 2000K, there is only a very small amount of decomposition into hydrogen and oxygen, but water will decompose into hydrogen and oxygen under the condition of electricity.
2H2O 2H2↑ + O2↑
1.2.2 Water reacts with metals. Many active metals can react with water, such as sodium, potassium, and iron.
2Na + 2H2O = H2 ↑ + 2NaOH
3Fe + 4H2O Fe3O4 + 4H2
1.2.3 Water reacts with non-metals. A few non-metals can react with water, such as fluorine, chlorine and carbon.
Cl2 + H2O HCl + HClO
1.2.4 Water reacts with some metal oxides and non-metal oxides can react with water. For example, sodium oxide, calcium oxide, carbon dioxide, and sulfur dioxide.
Na2O + H2O = 2NaOH
SO2 + H2O H2SO3
1.2.5 Reaction with other substances.
NH3 + H2O NH3.H2O
CaC2 + H2O → Ca(OH)2 + C2H2↑
2 Classification of water and its applications
2.1 Ordinary, heavy, and super-heavy water
There are three types of nuclides in elemental hydrogen, namely, ordinary hydrogen (1 proton in the nucleus, also called protium), heavy hydrogen (1 proton, 1 neutron, also known as deuterium), and superheavy hydrogen (1 proton, 2 neutrons in the nucleus, also known as tritium), which combine with oxygen to form ordinary water, heavy water, and superheavy water, respectively. The molecular formula of ordinary water is H2O. heavy water is also called deuterium oxide or deuterium water, the molecular formula is D2O. heavy water is a colorless, odorless, tasteless liquid, but some of its physical properties are slightly different from ordinary water. For example, the density of heavy water is 1.1044g/cm3 (25℃), while ordinary water is 0.99701g/cm3 (25℃). This is where heavy water gets its name. Heavy water has a melting point of 3.81°C and a boiling point of 101.42°C. The salts dissolve in heavy water. Salts are less soluble in heavy water than in ordinary water. For example, at 25°C, 100g of ordinary water can dissolve 35.92g of NaCl, while 100g of heavy water can only dissolve 30.56g of NaCl. many substances react with heavy water, and the reaction is slower than that of ordinary water. Heavy water has a negative effect on living things. Plant seeds immersed in heavy water cannot germinate, and fish will die quickly in heavy water. The average ordinary water contains about 0.015% heavy water. When water is electrolyzed, heavy water is enriched in the residual liquid of electrolyzed water because ordinary hydrogen (H2) is released six times faster than heavy hydrogen (D2). Current methods of producing heavy water include electrolysis, distillation and chemical exchange. The main use of heavy water is as a moderator (also called a decelerator) and coolant in reactors. Deuterium, produced when heavy water decomposes, is an important thermonuclear fuel. In chemistry and biology, heavy water is used as a tracer substance to study reaction mechanisms. The chemical formula of superheavy water is T2O, and each heavy water molecule consists of two tritium atoms and one oxygen atom. Superheavy water is extremely rare in natural water, with a proportion of less than one part per billion. The cost of producing superheavy water is tens of thousands of times higher than that of heavy water.
2.2 Water in life
2.2.1 Tap water Natural water after filtration, precipitation, disinfection of the water, the main component is water, followed by a number of ions such as Ca2+, Mg2+, Cl- and so on. Although the tap water after treatment, but there are traces of bacteria such as Escherichia coli, in addition to some other solutes, so tap water can not be directly consumed. The density of tap water is greater than that of pure water and has no fixed boiling point. Tap water can be drunk after heating and boiling, and can be used directly as industrial water.
2.2.2 Mineral water Mineral water is naturally gushing from deep underground or artificially exposed, uncontaminated underground mineral water. Mineral water contains a variety of minerals and trace elements beneficial to the human body, such as lithium, strontium, selenium, zinc, bromine, molybdenum, etc., physiological function is strong, the human body has a certain health care effect. Under normal circumstances, the chemical composition of mineral water, flow rate, water temperature and other dynamics in the natural fluctuation range is relatively stable.
2.2.3 Pure water Pure water is to rivers and lakes, tap water, etc. as a source of water, the use of distillation, electrodialysis, ion exchange, reverse osmosis and other treatment processes made. It is after complex and deep purification procedures to achieve sterile and pure. Pure water is the maximum removal of various elements in the water, only retain the water molecules, in the removal of harmful substances at the same time, but also removed the beneficial substances, so you can not drink pure water for a long time to drink with mineral water
2.2.4 Magnetization of water Magnetization of water is to make the water after high-tech superconducting magnets magnetization, so that the molecular structure of water to get a kind of water changes. After the magnetization of water, its physicochemical properties have undergone great changes, mainly manifested in the conductivity increases, PH value increases, density decreases, volatility accelerated, dissolved oxygen (DO) increases, insoluble substances in which the solubility increases, and so on. In most of the magnetic field to get magnetized water surface tension increases, the boiling point decreases; in a very few magnetic fields, the surface tension decreases, the boiling point increases. The freezing point of magnetized water does not change much. Because magnetized water has a structure and properties different from ordinary water, it has many uses in production and life. In medical treatment, it has stimulating and healing effects on human diseases such as high blood pressure, diabetes, blood thickening and kidney stones. Drinking magnetized water also has a role in eliminating exercise fatigue. In industry, the use of magnetized water has the purpose of inhibiting and preventing scale, exterminating dust, and improving the strength of concrete. In agriculture, using magnetized water to irrigate crops can activate various biological enzymes, enhance the biological activity of enzymes, promote the formation of chlorophyll, and improve photosynthesis, thus promoting the growth and development of crops, and improving the yield and quality of crops. Raising fish with magnetized water strengthens the growth of fish and their ability to resist disease and cold.
2.2.5 Super water The ordinary water is heated and evaporated into water vapor in a closed container, and the water vapor is condensed in a quartz capillary tube (inner diameter in the nm order of magnitude), so that the water obtained is called super water, which some people unscientifically call nano water. After treatment of the super-water binding structure has been greatly changed, the formation of a chain-like hexagonal ring structure of polymers, the diameter of its particles to the nm order of magnitude. Due to the special nature of the structure of super water, it has some properties different from ordinary water: ① its density is 1.4 times the density of ordinary water (ρ super = 1.4 ρ Pu); ② its viscosity coefficient is 15 times the viscosity coefficient of ordinary water (η super = 15 η Pu), low volatility; ③ the freezing point of the super water is-100 ° C. It still maintains its properties when it is heated up to 900 ~ 1000 ° C. It changes into a polymer when it is heated up to 900 ~ 1000 ° C. It is also called nano water. It becomes ordinary water when heated to 900~1000℃, and it will not change its characteristics whether heated, cooled or stored for a long time within -100~700℃. The high activity of super water makes it easier to enter between the molecules of other substances. Certain substances that are incompatible with ordinary water, such as fuel oil, are well soluble in super water, which enters between the oil molecules and changes the interactions between the molecules, making the molecular structure looser. Fuel oil containing super water is formulated in a certain proportion, with low ignition point and full combustion, which can improve the combustion rate and mechanical efficiency on one hand, and reduce air pollution on the other hand, with great economic benefits and good social benefits. Using super water as solvent, it can be made into a solution that remains liquid at low temperatures, and it can also be made into a solution that is anti-volatility and anti-permeability according to its low volatility and high viscosity coefficient, which is very useful in industry.
2.2.6 water water is used in life and production of people in the quality of miscellaneous drainage (excluding feces and kitchen drainage), miscellaneous drainage (excluding fecal sewage) and domestic sewage (wastewater), by the regeneration of the set of flow treatment to achieve a certain standard of water quality can be reused within a certain range of non-drinking miscellaneous water, and its water quality is between the upper water (clean water) and the lower water (sewage). For the "water" has a variety of interpretations, the sewage project is called "recycled water", the factory is called "recycled water" or "reuse water In sewage engineering, it is called "reclaimed water"; in factories, it is called "recycled water" or "reuse water"; in some cases, it is called "reclaimed water"; and generally, it is distinguished by the quality of the water. After treatment of water quality must meet the following conditions: (1) to meet the health requirements: its indicators are mainly coliform bacteria, total bacteria, residual chlorine, suspended solids, COD, BOD5, etc.; (2) to meet the requirements of people's sense of perception, no unpleasant feeling, the measurement of indicators of turbidity, chromaticity, odor, etc.; (3) to meet the requirements of the equipment structure, that is, the water is not easy to cause equipment, piping and severe Corrosion and scaling, the indicators are PH value, hardness, evaporation residue, dissolved substances. The treated water is generally used for flushing toilets, spraying roads, landscaping, car washing, as cooling water supplemental water.
2.3 hard water and soft water
2.3.1 soft water Water containing calcium ions, magnesium ions or less or no calcium ions, magnesium ions, the general hardness of less than 8 degrees of water for soft water.
2.3.2 hard water Water containing more calcium ions, magnesium ions, generally higher than 8 degrees of hardness is hard water. Hard water will affect the effect of detergent, hard water heating will have more scale. Industry in the use of hard water before the general softening.
2.4 Fresh water and brackish water
2.4.1 Fresh water Water Water containing little or no salt is generally used as civil or industrial water.
2.4.2 Brackish Water Water containing more salt, such as the water of northern salt lakes, some groundwater and seawater are brackish water. Answer Supplement 3 Investigation and Analysis of the Water Quality Condition of the Yangtze River and the Ancient Canal
Two days in October 16th and 17th five of us went to the Ancient Canal of Zhenjiang River and the inner Yangtze River and the nearby near side to conduct an examination and retrieve the water samples. Under the guidance of the teacher, these water samples were analyzed for pH, suspended solids, sediment content, COD, transparency and so on. The results of the analysis showed that the water quality of the outer rivers in the Yangtze River area is better and basically meets the national requirements. The Inner River and the ancient Canal is more seriously polluted, the water body is turbid, in some places the water quality is yellowish or greenish, more suspended solids, some areas of the water body irritating odor, sediment siltation, the water quality in most of the area only reaches the national regulations of class III or IV standards, a very small number of areas seriously do not meet the standards. In view of the above situation we several students visited some of the experts and did a survey of the situation, resulting in the deterioration of the water quality of the Neijiang River and the ancient Canal is due to the following aspects. First, the overall layout of Zhenjiang City is not very reasonable, more industries along the river, along the river, the ancient Canal side of the residential neighborhoods are dense. Secondly, some industrial wastewater is discharged into the Neijiang River and the ancient Canal without meeting the standard of treatment, and some manufacturers even discharge the untreated wastewater directly in order to reduce the production cost. Thirdly, the sewage from the community is not purified and discharged into the Neijiang River and the ancient Canal, and the phenomenon of littering and throwing is very serious along the banks of the ancient Canal, with some citizens urinating and defecating anywhere along the banks. Answer to add fourth, the environmental protection department management is not in place, the inspection is not strong enough, did not give severe investigation and punishment of violators. In order to have a good ecological environment in Zhenjiang, in order that Zhenjiang City can become a nationally recognized sanitary city and tourist city, in order that our citizens of Zhenjiang are healthy, and in order that our children and grandchildren will have a long and prosperous life, we strongly appeal to strengthen the management of the Neijiang River and the ancient Canal, and to improve the quality of the water of the Neijiang River and the ancient Canal. We put forward the following suggestions: First, the city leaders of Zhenjiang City, the overall planning, the serious pollution of enterprises forced to close or relocation. Secondly, all enterprises in the urban area should improve their sewage purification capacity, not for the sake of the enterprise's self-interest, without regard to the safety of the people's lives in the urban area. Thirdly, all citizens should establish the consciousness of environmental protection, protect the water quality of Neijiang River and the ancient Canal, everyone has the responsibility, don't throw the domestic garbage randomly. Fourth, the environmental protection department should raise the awareness of responsibility, to strengthen environmental supervision, to stop the arbitrary discharge of industrial wastewater and sewage.
The above investigation and research report, just our five students in the after-school time to do a little rough research, this is the first time we enter the high school stage in the comprehensive practical activities in the class attempt, which has a lot of shortcomings, I hope that the teacher and students to give corrections. I would like to thank the teacher for our careful guidance and great help, but also to have helped our classmates, teachers, leaders and social enthusiasts to express my heartfelt thanks.