Experiment on Amount of Dissolved Oxygen in Water

Experiment on Amount of Dissolved Oxygen in pissingResearchWater covers 70 percent of the earth and make up of 55% to 78% of the human body it is the nigh considerable compound on the planet. Its exists in swimming, solid, and brageous states in genius at room temperature, its a tasteless, odorless and colorless liquid state (Water structure and behaviour, 2014). Water in chemical cropula is H2O, devil enthalpy atoms distributively sh atomic number 18 one electron with the group O atom to form two covalent confederations and make a piss speck. The outer puzzle of group O is now full with 8 electrons and remains stable thereby it wont further re playact with some other heat content or atomic number 8 atoms ( chart 1). One of the important features of pissing supply molecule is that it forms and angle with hydrogen atoms at the tips and the atomic number 8 atom at the vertex. The angle formed by type O and hydrogen atoms isnt a typical tetrahedral angle of 109 degrees, because the comportment of two lone p picnics on the atomic number 8 molecule pushes the hydrogen molecules approximate together away from the lone pairs. This results in a smaller sequester angle of 104.5 degree ( graph 2). The reason that weewee is primarily a liquid under mensuration condition is because that type O is to a greater extent electronegative than hydrogen hydrogen is attracted strongly by oxygen results in the side of the oxygen atom is partial negative charge, while the hydrogen eradicate is part positive. This kind of molecule with a separation of electrical charges is called a dipole antenna meaning two poles. The charge difference al un unbrokens urine molecules to be attracted to from each one other and difficult to be separated, forming one single body of liquid. individually water system molecules bond to maximum of four other water molecules with two hydrogen atoms accepted and donates another two hydrogen atoms to others ( chart 3). Thi s type of bond is set as hydrogen bond occurs when hydrogen atom bonds with oxygen, atomic number 9 or nitrogen atom. Hydrogen bonding functions as two magnets bugger off together due to the opposite pole attraction. It is stronger than normal dipole carts betwixt molecules. The force is categorized as intermolecular force, a force act in the midst of neighboring particles (Hydrogen Bonding, 2013). The extensive hydrogen bonding between water molecules is responsible for physical properties in water, including property of high melting predict, boiling point since more cypher is required to break hydrogen bonds between molecules. Water result be in bungle, if the intermolecular force (force that holds water molecules together) is less than the thermal force that pushing the molecules apart while, the boiling point is suss outd as a point between behaving as a liquid and gasolene (Intramolecular Force, 2013). Another relevant property is that water has a very high specif ic heat capacity, due to the battlefront of extensive hydrogen bonding between water molecules a large join of energy (heat) is absorbed in breaking the bond (Specific Heat expertness of Water, 2014).Water has a high solvability, due to its a polar molecule with both positive and negative charges. Dissolving occurs when water bonds and separates the anion and cation of a substance. require putting an noggin compound into water, the individual ions react with the opposite foretoken regions of the water molecules with their garret bonds broken. This process is called dissociation, where ions are formed with atoms breaking mint from a molecule. The positively charged end of the water (H+) surrounds the negative ion of the ionic compound and the negatively charged end of the water (O2-) surrounds the positive ion of the ionic compound, this is called as a sphere of hydration, which separates the particles. This is the reason why water cannot displace non-polar molecule, because the polarity has no effect on a non-polar molecule (solubility, 2000). overturnIn this experiment, potassium thiosulfate was used to titrate water precedent amass in wetland at school in order to simulate and determine the amount of oxygen fade away in a normal river. The order used is called as Winkler Method, which involves iodometric titration the amount of oxygen in the precedent is obstinate indirectly via iodine. The method is considered to be the most reliable and precise method for DO analysis. DO presents in the river is relevant to the industry, river aquaculture, for the sake of keeping the oxygen level in a suitable range for aquatic animals to survive. there are a number of variables that affect DO presents in the river, temperature is the most crucial means that should be taken into account. Since rivers temperature varies throughout the twelvemonth with the change in the weathers or seasons. The temperature difference between summer and pass can be up to 10 degrees Celsius. Hence the experiment will focus on the effect of different temperatures on the amount of DO in the water sample. Theoretically, the amount of dissolved oxygen in the water is inversely proportional to the water temperature (table1). Its clearly shown in the graph that as the temperature rises, the solubility of oxygen in the water accrues (graph 4). Its recommended that DO analysis experiment should be done within the very(prenominal) day. DO level in the water source, where sample water is collected, whitethorn substitute dramatically at different time. It then consequently becomes a factor that affects the final result.IntroductionDissolved oxygen in water is defines as the amount of oxygen molecules that physically distributed in water. Notice that oxygen does not chemically react with water, since oxygen is a non-polar gas the intermolecular force of hydrogen bond in water molecule itself is stronger than the induced dipole attraction between the polar bond i n water and the nonionised bond gas, oxygen. Water molecules will rather remain hydrogen bonded to each other, then to allow a non-polar molecule (oxygen) to come between them (Aquaculture, 2000). on that point are ternary ways that oxygen gets in the water. First of all, its the difference of the parsimoniousness of oxygen in the air and the concentration of oxygen in the water causes diffusion to occur. Oxygen flows from high concentration (air) to low concentration (water). Secondly, its the partial pressure and find area that causes oxygen to shift through the water. For instance, in a river that flows rapidly, water turbulence increases the surface area of water for oxygen to diffuse across. Churning also allows air to hit water at a high pressure, allowing more oxygen to diffuse into the water. At last the presence of water plants produce oxygen in the water by doing the process of photosynthesis (How does oxygen get into the water?, 1999).Nowadays, commercial aquaculture is growing worldwide except in Africa. Fish and other aquatic organisms are a source of protein for human to intake. However, continues to harvest grotesque sources of fish will result in overfishing or even the passage of those aquatic species entirely. Aquaculture not only meets the human demand, but also allows furious species to breed and maintain the number of the wild aquatic species. There are a couple of aspects to look at in the aquaculture industry. The amount of dissolved oxygen in the water is relevant to maintain the water character reference for fish and aquatic species to grow. Oxygen is important in respiration and metabolism processes in any animal. Particularly for fish, the metabolic rate is highly cogitate to the oxygen concentration in water. For algid-water fish, the minimum DO requirement is 6mg per lambert for both tropical freshwater fish and tropical marine fish, its 5mg per litre. Once the level of DO is lower than the minimum requirement, fish may be affected by tissue hypoxia, their swimming activities will decrease and their immunity to diseases will also reduce (Aquaculture, 2000).Its obvious that fish and aquatic species rely on the DO level in the water to survive. Fish farmers should realize all the factors that affect the amount of dissolved oxygen in the water temperature is one of the main factors. The solubility of any gases is mutualist on the temperature. At a high temperature, the solubility of a gas in the water is low, while at a lower temperature the gas solubility in the water is relatively higher (graph5) (The personal effects of Temperature on the Solubility of Gases in the Universal Solvent (Water), 2009). As the temperature rises, the kinetic energy of the gas particles physically distributed in the water increases. This results in a more intensive gas particles motion, which allows intermolecular bonds between water molecules and gas molecules to be broken ca development gas to escape into the atmosphe re (Temperature and Pressure Effects on Solubility , 2003).The experiment consists of three parts, potassium iodate standardization, reagent blank finish and sample analysis. Begin with the KIO3 standardization, the exact concentration of potassium iodate is unknown, hence its titrated by sulfuric acid source to determine its essential concentration. Reagent blank determination is done in order to minimize the defect in the experiment. During the experiment, due to environment factors and contaminations, the result may be affected. Water is often used as a blank reagent and its responsible for determine the side effects on the final result. When doing the blank determination, water undergoes the same process as the sample. The value acquired is the blank value it is then subtracted from the samples result. Once the processes of standardization and blank determination have been done, water sample can now be analyzed.The chemical reactions are as follows 1) Manganese chloride reac ts with sodium hydroxide to give a white perciptate of manganous hydroxide. MnCl2 + 2NaOH Mn(OH)2 + 2NaCl 2) The presence of oxygen in the water sample reacts with manganous hydroxide, manganic basic oxide is then formed.2Mn(OH)2 + O2 2 MnO(OH)2 3) Manganic basic oxide is dissolved by sulfuric acid, and immediately reacts with sodium iodide to digest iodine. 2MnO(OH)2 + 4 H2SO4 2Mn(SO4)2 + 6H2O2Mn(SO4)2 + 4 NaI 2Mn SO4 + 2Na2SO4 + 2I24) Sodium thiosulfate is used to titrate iodine with the indicator, starch, to the end point. 4Na2S2O3 + 2I2 -2Na2S4O6 + 4NaIThe titer determines the amount of oxygen dissolved in the water sample with one mole of O2 reacts with 4 moles of sodium thiosulfate. The amount of oxygen concentration can be calculated from the above analysis with the following shapeDissolved oxygen = (mL/L)Notice that the unit is one milliliter of oxygen per litre of water, which can also be transferred into mg per litre.HypothesisIts predicted that the lower temperatur e will result in a higher solubility of oxygen in water. Under the condition of high temperature, oxygen gas forms weak molecular bonds with the water molecules. As a result, oxygen molecules will rise towards the surface and escape to the atmosphere, consequently reducing the amount of oxygen gas dissolved in the water. The solubility of oxygen is compared between cold river water and heated river water within this experiment, whilst other variables are kept constant including the size of the beaker, the location where river water is retrieved from and the resoluteness used for titration.Materials shape bottleDeionised waterStandard Potassium IodateSulfuric acid issueSodium iodide-sodium hydroxide reagentManganese chloride reagentMethodKIO3 Standardization (Titration)Label a public figure bottle with KIO3 Standard15ml of deionised water added into the BOD bottle10ml of standard potassium iodate with concentration of 0.00167M added into the BOD bottle with a pipette go around to mix1 ml of 50% sulphuric acid solution added into the BOD bottle1ml of sodium iodide-sodium hydroxide reagent added into the BOD bottle and pass1ml of manganese chloride reagent added into the BOD bottle and mix thoroughlyFill the BOD bottle with deionised water to the neck, and mix the solution by inverting the bottle a few times (BOD bottle now contains KIO3 standard solution, its identified as KIO3 standard bottle)Discard 50mL of KIO3 standard solution by using a 50mL volumetrical pipetteAdd 50mL of KIO3 standard solution into a clean 100ml conical flaskful by using a 50mL volumetric pipetteSet up the burette and fill it with sodium thiosulfate working(a) solutionPlace a white tile under the burette with the conical flask that contains KIO3 standard solution on top pass over titrating sodium thiosulfate into the conical flask until the solution turns a pale chickenhearted colour, stop titratingThree drops of starch solution added to the flask, then continues to titrate until the solution turns colourlessVolume of sodium thiosulfate added recordedRepeat the process until three readings within 0.05mL of each other acquiredReagent Blank determination TitrationAdd 15mL of deionised water into a 250mL conical flask1mL of KIO3 standard solution added to the conical flask1mL of 50% sulphuric acid added to the flask1mL of sodium iodide-sodium hydroxide added to the flask1mL of manganese chloride reagent added to the flaskAppendixTable1 (The Winkler Method Measuring Dissolved Oxygen, 2013)Graph 1 (Waters Influence on Temperature, 2013)Graph 2 (WATER DESIGNED FOR LIFE, 2013)Graph 3 (Hydrogen bond, 2014)Graph4 (Lecture Water Chemistry Dissolved Gases Oxygen)Graph5 (Why oxygen dissolved in water is important , 1998)