...ADVANTAGES AND DIS ADVANATGES OF CHLORINE AS A DISINFECTANT IN WATER TREATMENT Chlorine reactions depend on the type of chlorine added to the water (Water Treatment by Chlorine) as well as on the pH of the water itself. Each of the reactions uses up the chlorine in the water and produces either chloride ions or hydrochloric acid, which have no disinfecting properties. The total amount of chlorine which is used up in reactions with compounds and destroying pathogens in the water is known as the chlorine demand. A sufficient quantity of chlorine must be added to the water so that, after the chlorine demand is met, there is still some chlorine left as free residual chlorine to take care of any further contamination. Reactions of Chlorine with Water When chlorine gas enters the water, the following reaction occurs: The chlorine reacts with water and breaks down into hypochlorous acid and hydrochloric acid. Chlorine + Water Hypochlorous Acid + Hydrochloric Acid Cl2 + H2O –> HOCl + HCl Hypochlorous acid may further break down, depending on pH: Hypochlorous Acid Hydrogen Ion + Hypochlorite Ion HOCI H+ + OCl- The double-sided arrows in the equations mean that the reaction is reversible. Hypochlorous (HOCL) acid may break down into a hydrogen ion and a hypochlorite (OCL) ion, or a hydrogen ion and a hypochlorite ion may join together to form hypochlorous acid.Advantages and Disadvantages of Chlorine Advantages of Chlorine as disinfectant are: 1....
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...sample of reservoir water when it is disinfected with chlorine or chloramine and to what extent do both chloramine and free chlorine decompose when exposed to ultraviolet light?” Abstract This investigation aims to find out how pH affects the concentration of trihalomethanes formed in a sample of reservoir water when it is disinfected with chlorine or chloramine and the extent to which both free chlorine and chloramine decompose when exposed to ultraviolet light. Headspace gas chromatography and mass spectrometry were used to measure the concentration of the four main constituents of total trihalomethanes (TTHMs), namely chloroform,...
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...essential for healthy plant growth; carbon, hydrogen, oxygen, nitrogen, phosphorus, potassium, calcium, magnesium, sulfur, boron, copper, iron, manganese, zinc, molybdenum, and chlorine. What are the symbols of these elements? a. Carbon - C b. Hydrogen – H c. Oxygen - O d. Nitrogen – N e. Phosphorus – P f. Potassium – K g. Calcium – Ca h. Magnesium – Mg i. Sulfur – S j. Boron – B k. Copper – Cu l. Iron – Fe m. Manganese – Mn n. Zinc – Zn o. Molbdenum – Mo p. Chlorine - Cl 2. For the proper functioning and survival of the human organism, trace amounts of 14 metals and metalloids are essential in the diet. Their symbols are Ca, P, K, S, Na, CI, Mg, Fe, Zn, Cu, Mo, Co, I, and Se. What are the names of these elements? q. Ca – Calcium r. P – Phosphorus s. K – Potassium t. S – Sulfur u. Na – Sodium v. CI – Chlorine w. Mg – Magnesium x. Fe – Iron y. Zn – Zinc z. Cu – Copper {. Mo – Moldbenum |. Co – Cobalt }. I – Iodine ~. Se - Selenium 3. Classify each of the following phenomena as a physical or chemical change; . The detonation of trinitrotoluene (TNT) produces carbon monoxide, water, nitrogen, and carbon. i. Chemical Change . When exposed to an ignition source, hexane vapor ignites at -7°F (-22°C). ii. Chemical Change . Battery...
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...Chemical compatibility is a measure of how stable a substance is when mixed with another substance.[1] If substances mix and do not change they are considered compatible. If substances mix and change or do not mix at all they are considered incompatible. For example, because bleach and ammonia, both commonly used as cleaners are not compatible chemicals, as they react. The recants in this case are dangerous so care must be taken not to allows these chemicals to mix when attempting to use them as cleaners. Chemical Compatibility Concerns in Storage Chemicals play an important role in many workplace applications. The inherent hazards of chemicals can be reduced by minimizing the quantity of chemicals on hand. However, when chemicals must be in-house, proper storage and handling can reduce or eliminate associated risks. Proper storage information can usually be obtained from the Safety Data Sheet (SDS), label or other chemical reference material. As required by 29 CFR 1910.1200, an SDS must be on hand for every chemical in your workplace. The SDS and chemical label can be consulted for information on special storage requirements. The SDS can also answer questions such as: * Is the chemical a flammable? * Is the chemical a corrosive? * Does the chemical need to be stored other than at ambient temperature? * Is the chemical an oxidizer or reducer? * Is the chemical light sensitive? * Does the chemical require any special handling procedures? Typical...
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... +2 B +2 +3 C +3 +2 D +3 +4 ( ) 3. When substance X is added to aqueous potassium iodide and acidified potassium manganate(VII) solution separately, both resultant solutions appear colourless. In the two reactions, substance X is acting as A an oxidising agent only. B a reducing agent only. C both an oxidising agent and a reducing agent. D neither an oxidising agent nor a reducing agent. ( ) Section B (12 marks) Answer all the questions in the spaces provided below. 4. An oxyacid is an acid that contains oxygen atom(s) bonded to hydrogen atom(s) and at least one other element. Sulfuric acid (H2SO4), phosphoric acid (H3PO4) and nitric acid (HNO3) are all oxyacids. Chlorine forms...
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...Chemistry Unit 2 AS Group 7, the halogens - Physical properties, fluorine is a pale yellow gas, chlorine a greenish gas, bromine a red-brown liquid and iodine a black solid o Fluorine is small and leads to the repulsion between non-bonding electrons because they are so close together o The atoms get bigger as we go down the group because each element has one extra filled main level of electrons compared with the one above it |Halogen |Atomic number |Electron Arrangement |Electronegativity |Atomic radius nm |Melting point K |Boiling Point K | |Fluorine |9 |[He]2s22p5 |4.0 |0.071 |53 |85 | |Bromine |35 |[Ar]3d104s24p5 |2.8 |0.114 |266 |332 | Electronegativity - This is a measure of the ability of an atom to attract electrons, or electron density towards itself within a covalent bond o This depends on the attraction between the nucleus and bonding electrons in the outer shell, which depends on the balance between the nuclear charge and the distance between the nucleus and the bonding pairs plus the shielding effect of inner shells of electrons Melting and boiling points - Melting and boiling points involve weakening and breaking...
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...1 UTME 2001 Type R Questions Use the graph below to answer questions 1 and 2. 100 200 Time (mins) T(0C) 0 1 2 3 4 5 6 7 8 300 Liquid Vapour Solid 1. If the gas is cooled, at what temperature will it start to condense? (A) 1250C (B) 1500C (C) 1750C (D) 2500C 2. How long does it take all the solid to melt? (A) 2.5 mins (B) 6.0 mins (C) 1.0 mins (D) 3.0 mins 3. 25cm3 of a gas X contains Z molecules at 150C and 75mmHg. How many molecules will 25cm3 of another gas Y contain at the same temperature and pressure? (A) 2Y (B) 2Z (C) Z (D) Y 4. What mass of water is produced when 8.0g of hydrogen reacts with excess oxygen? (A) 36.0g (B) 8.0g (C) 72.0g (D) 16.0g [H = 1, O = 16] 5. A particle that contains 9 protons, 10 neutrons and 10 electrons is a (A) negative ion (B) positive ion (C) neutral atom of a non metal (D) neutral atom of a metal 6. Cancerous growth are cured by exposure to (A) γ -rays (B) β -rays (C) α -rays (D) x-rays 7. An oxide XO2 has a vapour density of 32. What is the atomic mass of X (A) 32 (B) 20 (C) 14 (D) 12 [O = 16] 8. Milikan’s contribution to the development of atomic theory is the determination of (A) charge on electron (B) positive rays (C) charge to mass ratio (D) cathode rays 9. Four elements W, X, Y, and Z have atomic numbers 2, 6, 16 and 20 respectively. Which of these elements is a metal? (A) X (B) W (C) Z (D) Y 10. An element X with relative atomic mass 16.2 contains two isotopes 16X 8 with relative abundance of 90% and X m8 with relative abundance of 10%...
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...spectrophotometer[Dobsonmeter]that could be used to measure stratospheric ozone from the ground. Ozone layer acts as a shield for the earth from very harmful UV rays.If we damage the ozone layer anymore then we would put ourselves at an increasingly greater risks because we cannot survive without the ozone layer.Exposure to UV rays causes skin cancer,damage crops and harms ocean life,e.g polar shifting, that is,a complex event that occurs when uneven melting of ice occur_a major hole is now over Antarctica,where there are ice shitfs.If this melts,it could increase coastal flooding and the poles could shift,causing a violent shift in climate. Ozone is a triatomic form of oxygen[02],found in the Earth atmosphere.A combination of low temperature,elevated chlorine and bromine concentration in the upper stratosphere are responsible for the destruction of ozone.The production and emission of chlorofluorocarbons[CFCs] is the leading cause of ozone layer...
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...Case Study Turnaround at the Preston plant The Preston plant of Rendall Graphics was located in Preston, Vancouver. The plant was bought from the Georgetown Corporation by Rendall in March 2000. The plant produced Precision coated papers for ink-jet printers which accounted for the majority of the plant’s output. The plant started to experience problems in the quality of their output of the ink-jet paper and had received feedback in late 1998 from Hewlett-Packard (HP) about the problem. The team at Preston worked to resolve the problem and in October of 1999 made recommendations for a revised and improved coating formulation. However in 2000, productivity, scrap and re-work levels continued to be poor. Operations Management team’s response was to increase the speed of the line and made a number of changes to operating practice in order to raise productivity. In the spring of 2000, two significant events happened to the Preston plant. Rendall Corporation purchased the plant, even though it was losing around $2 million a year. Rendall was not impressed by what they found at the plant and it seems that they did not do a very good analysis of the overall operations of the plant and the management of its operations. The second event that happened was that HP asked the plant to bid on a contact for a new ink-jet platform. The main concern that the operations management had with HP’s observations and feedback was that, HP continued to have complaints on quality...
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...1) General Halogens are a group of nonmetal elements from group 7 of the Periodic Table. It contains fluorine (F), chlorine (Cl), bromine (Br), iodine (I) and astatine (At). Ununseptium (Uus) is an artificially created element and it is sometimes considered to be a halogen. Halogens have a valency of 1 and a halogen ion has a charge of 1-. Like other groups, there are similarities and trends (both physical and chemical) within the different elements in this group. Below is a table showing the electronic configuration and formula of the halogens. |Halogen |Room temperature (20 oC) |Vapour Colour | |Fluorine |Yellow Gas |Yellow | |Chlorine |Green Gas |Green | |Bromine |Red/Brown Liquid |Orange | |Iodine |Dark Grey/Violet Solid |Purple/Violet | |Astatine |Black Solid |Dark Purple | The halogens become darker as you go down the group. Fluorine is very pale yellow, chlorine is yellow-green and bromine is red-brown. Iodine crystals are shiny purple-black but easily turn into a dark purple vapour when they are warmed up. Common properties The halogens have the following properties in common: • they are non-metals • they have low melting and boiling points • they are brittle when...
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...atoms present. Non-metal compounds are made of molecules: Carbon dioxide contains CO2 molecules Methane (natural gas) contains CH4 molecules AN ION is an atom or group of atoms with an electrical charge (+ or -). Metal compounds such as sodium chloride or copper sulphate contain ions. Sodium chloride is made of Na+ and Cl- ions Copper Sulphate is made of Cu2+ and SO42- ions Note that metals form positive ions while non-metals form negative ions. A solid is represented by (s). e.g. H2O(s) is ice. A liquid is represented by (l) e.g. Fe(l) is molten iron. A gas is represented by (g) e.g. H2O(g) is steam. A solution in water is represented by (aq). Salt dissolved in water is NaCl(aq). You should remember that the common gases are diatomic (have 2 atoms in each molecule). These are Oxygen O2; Hydrogen H2; Nitrogen N2; and Chlorine Cl2. Elementary Particles Atoms are made up of smaller particles called protons, neutrons and electrons. The protons and neutrons cluster together in a small nucleus at the centre of the atom while the electrons orbit the nucleus. The main properties of the particles are: |Particle |Mass |Charge | |PROTON |1 |+1 | |NEUTRON |1...
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...1. (a) By referring to electrons, explain the meaning of the term oxidising agent. ..................................................................................................................................... (1) (b) For the element X in the ionic compound MX, explain the meaning of the term oxidation state. ..................................................................................................................................... (1) (c) Complete the table below by deducing the oxidation state of each of the stated elements in the given ion or compound. |Oxidation state| Carbon in CO|| Phosphorus in PCl|| Nitrogen in Mg3N2|| (3) (d) In acidified aqueous solution, nitrate ions, NO, react with copper metal forming nitrogen monoxide, NO, and copper(II) ions. (i) Write a half-equation for the oxidation of copper to copper(II) ions. ........................................................................................…............................... (ii) Write a half-equation for the reduction, in an acidified solution, of nitrate ions to nitrogen monoxide. ........................................................................................…............................... (iii) Write an overall equation for this reaction. ........................................................................................…............................... (3) (Total 8 marks) 5. (a) The following is an equation for a redox reaction. ...
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...PROPERTIES OF THE PERIOD 3 OXIDES These pages explain the relationship between the physical properties of the oxides of Period 3 elements (sodium to chlorine) and their structures. Argon is obviously omitted because it doesn't form an oxide. A quick summary of the trends The oxides The oxides we'll be looking at are: |Na2O |MgO |Al2O3 |SiO2 |P4O10 |SO3 |Cl2O7 | | | | | |P4O6 |SO2 |Cl2O | Those oxides in the top row are known as the highest oxides of the various elements. These are the oxides where the Period 3 elements are in their highest oxidation states. In these oxides, all the outer electrons in the Period 3 element are being involved in the bonding - from just the one with sodium, to all seven of chlorine's outer electrons. The structures The trend in structure is from the metallic oxides containing giant structures of ions on the left of the period via a giant covalent oxide (silicon dioxide) in the middle to molecular oxides on the right. Melting and boiling points The giant structures (the metal oxides and silicon dioxide) will have high melting and boiling points because a lot of energy is needed to break the strong bonds (ionic or covalent) operating in three dimensions. The oxides of phosphorus, sulphur and chlorine consist of individual molecules - some small and simple; others polymeric. The attractive forces between these molecules will be van der Waals...
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...0f 0.020 mol dm-3 potassium manganate (VII) is required to oxidise completely 1.0 x 10-3 mol of the salt KHC2O4.H2C2O4? (November 2009 ‘A’ Levels Paper 1 Question 2) A 3. 20 cm3 B 40 cm3 C 50 cm3 D 125 cm3 A small peptide X is hydrolysed according to the following reaction. X 2NH2CH2CO2H + NH2CH(CH3)CO2H + 2NH2CH(CH2OH)CO2H? (Mr = 75) (Mr = 89) (Mr = 105) What is the Mr of X? (November 2009 ‘A’ Levels Paper 1 Question 30) A 359 B 377 C 431 D 449 Structured 1. Calcium sulphate occurs naturally as the dehydrate gypsum, CaSO4.2H2O. When heated to 160ºC, gypsum loses some of its water to give plaster of Paris, which is used for making fine plaster casts and for setting broken limbs. During the heating process, 100 g of gypsum loses 15.7 g of water. Calculate the formula of plaster of Paris. (November 2002 ‘A’ Levels Paper 3 Question 4) 2. When aqueous ammonia is added to an aqueous solution of an aluminium salt, a precipitate of ‘aluminium hydroxide’ is formed as an amorphous gelatinous mass. When dried, this precipitate forms a white crystalline compound called boehmite....
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...made up of the four natural elements: earth, water, air and fire, which work simultaneously to create one united universe (Hebert). The symbolism concerning the natural elements plays a significant role within Timothy Findley’s The Wars, as he demonstrates an evolution of the archetypal symbolic nature of the elements. In this novel, a young Canadian troop by the name of Robert Ross is being studied by a researcher after his notable death. The novel entails that the reader follows him through his journey in the war and provides a personal opinion on his experiences throughout. Robert Ross, the protagonist of the story, is also seen as a character...
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