...Oxygen Student’s Name Institution Oxygen Oxygen is one of the most vital elements. People cannot exist without it. This element does not only give us life but also kills bacteria in our bodies without affecting the ones that we need. No other medicine is able to do it exactly like oxygen does. For almost five centuries the chemists all over the world have been arguing about who was the one to discover this element. There were three main candidates for this title. The first one was a pharmacist from Sweden Carl Wilhelm Scheele, the second was an English churchman Joseph Priestley, and the third was a French chemist Antoine Lavoisier. Scheele was the first person who noticed that during the heating of such elements as mercuric oxide, carbonate mercury and silver carbonate they give the same gas, which he called “fire air”. The pharmacist described this phenomenon in his book Chemical Observations and Experiments on Air and Fire, which he wrote in 1775 but it wasn’t published until 1777. Nevertheless, in reality, the secret of the “fire air” remained a mystery to him. The reason for this was a popular in those days theory, on which it was assumed that any substance can be burned only if it has a lot of special combustible matter – phlogiston. Karl Scheele was also a proponent of this theory, so he explained that "fire air" has a high affinity (attraction) to the phlogiston and therefore it burns so quickly. This was quite plausible, but it was really...
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...What is Dissolved Oxygen? Dissolved Oxygen in a stream may vary from 0 mg/l to 18 mg/l. Readings above 18 mg/l are physically impossible. Dissolved oxygen gets into the water by diffusion from the atmosphere, aeration of the water as it tumbles over falls and rapids, and as a waste product of photosynthesis. What factors affect the DO level? Reduced DO levels in stream water may be because the water is too warm. The increased molecular activity of the warm water pushes the oxygen molecules out of the spaces between the moving water molecules. Decreased DO levels may also be indicative of too many bacteria and an excess amount of biological oxygen demand - BOD (untreated sewage, partially treated sewage, organic discharges, anoxic discharges) which use up DO. A third reason for decreased DO may be fertilizer runoff from farm fields and lawns. The same fertilizer which was meant to make land plants grow better now makes the aquatic plants do the same. If the weather becomes cloudy for several days, respiring plants will use much of the DO while failing to photosynthesize. When the increased numbers of aquatic plants eventually die, they support increasing amounts of bacteria which use large amounts of DO. Water Quality Index Chart- Based on Dissolved Oxygen Water Quality Index and BOD - Biological Oxygen Demand Students should be aware that plants, in general, only produce oxygen when light is available for photosynthesis. Rooted aquatic...
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...What is dissolved oxygen? Dissolved oxygen alludes to the level of free oxygen not bonded to any existing molecule in the water or other liquid substances. It is an important parameter in assessing water quality because of its influence on the organisms living within a body of water. In limnology (lakes studies), dissolved oxygen is a crucial factor second only to water itself. A dissolved oxygen level that is too high or too low can harm aquatic life and affect water quality. Non-compound oxygen, or free oxygen (O2), is oxygen that is not bonded to any other element. Dissolved oxygen is the existence of these free O2 molecules in the water. The molecule of oxygen bonded in a water molecule (H2O) is in a compound and does not count toward dissolved oxygen levels (Rivsbech et al., 1988). Dissolved oxygen from the atmosphere Dissolved oxygen goes into the water through the air or as a byproduct of a plant. From the air, oxygen can slowly diffuse across the water’s surface from the nearby atmosphere, or be assorted in rapidly through aeration, whether natural or man-made. Water aeration can be brought about by wind (creating...
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...Oxygen transfer Abstract (193 words) This practical was carried out with the aim of determining the KLa value for oxygen transfer as well as examining the relationship between KLa and other fermenter variables like speed of the impeller and air flow rate, thereby calculating the values α and β in the KLa correlation: KLa = K[Pg/V]α (Vs)β KLa is the volumetric liquid phase mass transfer coefficient indicative of the mass transfer of oxygen dissolved in the liquid to the cell. It is calculated using the dynamic method which is usually used for vessels which are less than 1m in height because there is nitrogen gas hold-up in the vessel when air is reintroduced and the measurement of concentration of oxygen in the liquid does not reflect the kinetics of simple oxygen transfer until a hold-up of air in established. The measured parameters included gassed power (Pg), impeller speed, flow rate (indirectly superficial gas velocity) and DOT%. It was seen that as the power input was increased, the KLa increased for the same flow rate and that this increase was greater than increase in the flow rate of the gas, which shows confirms the results described in the literature. Introduction (326 words) Cells in aerobic cultures require oxygen for metabolism and growth. The rate of oxygen transfer from aerated liquid to the cell is especially important at high cell densities, when cell growth is likely to be limited by the availability of oxygen in the medium. The solubility of oxygen...
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...Percentage of Oxygen in Compound-Stoichiometry/ Catalysis Page 2 Table of Contents Introduction Page 3 Experimental Procedure Page 4- 5 Results Page 6-7 Discussion Page 7 References Page 8 Page 3 Introduction This laboratory the weighting techniques and the use of stoichiometry to calculate percentages of substances were reviewed. To calculate the percent purity of sample, stoichometry relationships were used. In this lab stoichiometric relationship was use to find the percent of oxygen in potassium chlorate and also the percent purity of a sample provided. By definition, Stoichiometry is the quantitative relationship amongst elements in a compound to reactant ratio during a chemical reaction. Potassium chlorate (KClO₃), like many other oxygen composing compounds, is decomposed well by heat. Essentially there is an endothermic reaction that by the aid of a catalyst and heat will produce potassium chloride and oxygen. This equation looks as follows: KClO₃sMnO₂heat2KCls+3O₂(g) This process can happen without the presence of manganese dioxide (MnO₂), but it will take a very long time. Instead, MnO₂ is used as the catalyst to expedite the heating temperature and does not contribute to the overall oxygen output Page 4 Experimental procedure First, obtain two clean and dry 25x200mm Pyrex test...
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...DISSOLVED OXYGEN Sl. No. Contents Preamble 10.1 Aim 10.2 Introduction 10.2.1 Environmental Significance 10.3 Principle 10.4 Materials Required 10.4.1 Apparatus Required 10.4.2 Chemicals Required 10.5 Sample Handling and Preservation 10.5.1 10.6 Precautions Procedure 10.6.1 Preparation of Reagents 10.6.2 Testing of Water Sample 10.7 Calculation 10.7.1 Table 10.7.2 Data Sheet 10.8 Interpretation of Results 10.9 Inference 10.10 Evaluation 10.0 EXPERIMENT ON DETERMINATION OF DISSOLVED OXYGEN PREAMBLE: “How to determine dissolved oxygen in Water and Wastewater”. Test procedure is in accordance to IS: 3025 (Part 38) - Reaffirmed 2003. In addition to our Indian Standard, we also discuss in brief regarding the procedure stated in (1) APHA Standard Methods for the Examination of Water and Wastewater - 20th Edition. Method 4500-O G. (2) Methods for Chemical Analysis of Water and Wastes, EPA-600/4-79-020, USEPA, Method 360.1. 10.1 AIM To determine dissolved oxygen (DO) in the given water sample with the stipulations as per IS: 3025 (Part 38) - Reaffirmed 2003. 10.2 INTRODUCTION Before performing this experiment, few questions may arise to the learners: 1. What is meant by Dissolved Oxygen (DO)? Is it oxygen in dissolved form? 2. Why we need to determine DO? 3. What are the methods available to determine DO? 4. Is it measured in natural water or wastewater? 5. Whether is it mandatory as per our codal provision to determine DO? The term Dissolved Oxygen is used...
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...Introduction: Measuring dissolved oxygen in a body of water is necessary to determine whether or not it has enough oxygen content in order to be habitable to various aerobic organisms and marine life. This measurement gives us the amount of oxygen content per unit of volume (usually mg/L), and from this, we are able to determine the type of organisms that can thrive there. This concentration is dependent upon the salinity and chlorinity of the water, as well as the temperature, atmospheric pressure, flow rate, and distance along the stream from the deoxygenated parts of the water. The purpose of this laboratory assignment is to collect data about the concentration of dissolved oxygen in a pre-built setup with control factors, and from this we will apply our knowledge to determine if the cleaned wastewater from a water treatment plant will have the desirable concentration of dissolved oxygen before being pumped into a local river. Experimental Procedures: Equipment: a) Supply of nitrogen-infused deoxygenated water flowing at a steady rate. b) Seven (7) sections of PVC half-pipes, each placed approximately 15-20.5cm lower than the previous (going downstream) for six (6) vertical drops. c) Four (4) small rocks placed in channel 7 approximately equidistant from each other. d) One (1) tape measure. e) One (1) oxygen level meter. f) One (1) bucket to collect the water after flowing through the system. g) One (1) graduated cylinder, used to measure...
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...the Percentage of Oxygen in Air” lab, the students were to read the background and purpose information on the lab. The experiment was designed to determine the percentage of oxygen in a given air sample. The purpose of this lab, although, was to teach students to be familiar with laboratory procedures and safety. On the day of the lab, Mrs. Robinson spoke to the entire class on how to do the experiment and the materials that we needed. We then proceeded to put on our safety aprons and goggles. My partner, Wyatt, and I gathered the materials of a 100mL graduated cylinder (with a 0.1 accuracy), a pie tin, a small candle, and a lighter. We needed to be incredibly safe with the lighter. The only chemical is water. When we first got our pie tin, I noticed there was some wax already on the bottom meaning that it was already used. We had trouble getting the candle to stick to the pie tin, but we did and we filled the rest of the pie tin with water. When we lit the candle I could smell the fire. The graduated cylinder was placed over the candle and the flame started to die down and I could see smoke in the rest of the cylinder. As the flame died, the water around the candle started to rise. When the flame did eventually die, the water vacuumed up at a faster rate. The same results followed with other trials only with different readings. Although I noticed that if the wick of the candle was wet, it crackled before lighting. This phenomenon occurs because the oxygen in the air trapped...
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...effect the abiotic factor O2 concentration has on the abundance of Chaoborus, also known as the phantom midge larvae. This entailed using a net to catch the organism and counting them under timed conditions. The test was repeated in a vegetated and open area of water in order to be able to evaluate different oxygen concentrations. The abundance of phantom midge larvae was measured by manually counting and the concentration of oxygen at the two sites was measured using an oxygen probe. Results indicated that in open areas the number of midge larvae was vastly larger than that of vegetated areas; they had also confirmed that the area of open water had a lower O2 concentration as compared to the vegetated area. These results are fitting to the scientific background of Chaoborus, as they are known to inhabit water with less concentration of oxygen1. Further analysis of these results were conducted using a Mann-Whitney U-Test which proved there was a significant difference in the number of phantom midge larvae in the two areas for which the reason was the different concentrations of oxygen. RESEARCH & RATIONALE This aim of this investigation is to measure the effect Oxygen Concentration of fresh pond water, an abiotic factor, has on the number of Chaoborus (Phantom Midge Larvae) present by studying their abundance in areas of the pond which are surrounded by vegetation and comparing it to the results acquired from an area of open water. D2- diagram showing a phantom midge...
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...EXPERIMENT 11: DETERMINATION OF DISSOLVED OXYGEN IN A WATER SAMPLE (WINKLER METHOD) INTRODUCTION In an alkaline solution, dissolved oxygen will oxidize manganese(II) to the trivalent state. 8OH-(aq) + 4Mn2+(aq) + 2H2O(l) －－＞ 4Mn(OH)3(s) The analysis is completed by titrating the iodine produced from potassium iodide by manganese(III) hydroxide. 2Mn(OH)3(s) + 2I-(aq) + 6 H+(aq) －－＞ 2Mn2+(aq) + I2(aq) + 6H2O(l) Sodium thiosulphate is used as the titrant. Success of the method is critically dependent upon the manner in which the sample is manipulated. At all stages, every method must be made to assure that oxygen is neither introduced to nor lost from the sample. Furthermore, the sample must be free of any solutes that will oxidize iodide or reduce iodine. Chemicals: Manganese(II) sulphate solution – prepared by dissolving 48 g of MnSO4.4H2O in water to five 100 cm3 solution; alkaline potassium iodide solution—prepared by dissolving 15 g of KI in about 25 cm3 of water, adding 66 cm3 of 50% NaOH, and diluting to 100 cm3; concentrated sulphuriv(VI) acid; 0.0125 M sodium thiosulphate solution; starch solution (freshly prepared). Apparatus: 250 cm3 volumetric flask, 250 cm3 conical flask, measuring cylinders, titration apparatus, magnetic stirrer Procedure: 1. Use a 250 cm3 volumetric flask to collect water sample. Fill the flask completely with water without trapping any air bubbles. 2. Add 1 cm3 of manganese(II) sulphate solution to the sample using a pipette...
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...SPIN AWARENESS AND AVOIDANCE Objective To teach the student the avoidance and proper recovery from spins. Elements • Uncoordinated stalls • Aerodynamics of a spin • Recovery procedure Schedule Discussion 0:30 Equipment Model airplane Instructor Actions Discuss what is a spin (an aggravated stall that results in autorotation). Autorotation results from unequal angles of attack on the wings. The key is aggravated (i.e. uncoordinated). Draw or show the corkscrew/helical flight path of a spin. The difference between a spin and a steep spiral: spin—airspeed low, wings stalled; spiral—airspeed increasing, not stalled. Discuss the aerodynamics of a spin. Draw a wing in straight-and-level flight and in slow flight. Use actual angles of attack. Typical light aircraft wings stall at 18-22º. How can you enter a spin? Wing exceeds critical angle of attack with yaw acting on aircraft (uncoordinated). That is, a stall when in a slipping or skidding turn. Danger of base to final turn—cross controlled stall leading to spin. The high wing has the greatest lift due to the greater airspeed, and overall less drag and lower angle of attack. The low wing has the least lift (due to lower airspeed) and greatest parasitic drag due to its higher angle of attack. Center of gravity affects the spin characteristics. An aft CG makes spin recovery more difficult. The worst case is the aircraft may enter into a flat spin if CG is too far back, making recovery impossible. Center...
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...Hypothesis I will investigate whether the concentration of oxygen in pond water will affect the abundance of Phantom Midge Larvae (Genus Chaoborus) by comparing a pond that has a higher oxygen concentration with a pond that has a lower oxygen concentration. Alternative Hypothesis: The lower the oxygen concentration, the higher the abundance of Phantom Midge Larvae. Null Hypothesis: There will be no significant difference between the oxygen concentration and the abundance of Phantom Midge Larvae. Any difference is due to chance. Research The Phantom Midge Larvae (Genus Chaoborus) A phantom Midge Larvae (Genus Chaoborus) otherwise known as a ‘glassworm’ due to its transparent appearance is a form of Midge Larva which are very abundant in static water such as ponds and lakes. The body is in distinct segments with small hairs and the last segment has a number of stiff hairs which acts as a rudder. They breathe through the end of their abdomen and have two small eyes on the front of their body. They can survive is polluted waters with little oxygen. Unlike other air filled invertebrates, the Phantom Midge Larvae has two visible black air sacs either side of their body which allows them to migrate up and down in static water. They can be found in waters as deep as 70m where there is little oxygen and they are able to avoid predators which are found in shallower waters. Phantom Midge Larvae are consumed by other aquatic predators such as puffers, young cichlids and bumblebee...
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...OF DISSOLVED OXYGEN BY WINKLER TITRATION 1. Background Knowledge of the dissolved oxygen (O2) concentration in seawater is often necessary in environmental and marine science. It may be used by physical oceanographers to study water masses in the ocean. It provides the marine biologist with a means of measuring primary production - particularly in laboratory cultures. For the marine chemist, it provides a measure of the redox potential of the water column. The concentration of dissolved oxygen can be readily, and accurately, measured by the method originally developed by Winkler in 1888 (Ber. Deutsch Chem. Gos., 21, 2843). Dissolved oxygen can also be determined with precision using oxygen sensitive electrodes; such electrodes require frequent standardization with waters containing known concentrations of oxygen. They are particularly useful in polluted waters where oxygen concentrations may be quite high. In addition, their sensitivity can be exploited in environments with rapidly-changing oxygen concentrations. However, electrodes are less reliable when oxygen concentrations are very low. For these reasons, the Winkler titration is often employed for accurate determination of oxygen concentrations in aqueous samples. 2. Scope and field of application This procedure describes a method for the determination of dissolved oxygen in aqueous samples, expressed as mL O2 (L water) -1. The method is suitable for the assay of oceanic levels of oxygen in uncontaminated...
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...DETERMINATION OF DISSOLVED OXYGEN IN WATER INTRODUCTION The dissolved oxygen content is an important index when considering its suitability for town supply. A good clean potable water will give dissolved oxygen value close to the theoretical value for the saturated solution of oxygen in water. When there is pollution from organic matter and other trade effluents, the dissolved oxygen is up in various biochemical oxidation processes and its is only slowly replaced through surface absorption. Such water will give a low dissolved oxygen content until oxidation is completed. Adequate dissolved oxygen is necessary for the life of fish and other aquatic organisms. The methods described below for the determination of oxygen in water is based on that devised by Winkler. When manganese hydroxide is precipitated in the water sample it is quickly oxidized to higher hydrated oxides (probably in the four valent state) by the dissolve oxygen. Iodine, equivalent to the dissolved oxygen content, is then liberated on acidification in the presence of iodine, and it may be titrated with standard thio‐sulphate. INTERFERENCES AND PRE – TREATMENT Most oxidising and reducing substances e.g dissolved organic substances, nitrite ions, higher‐valency manganese compounds, active chlorine, sulphide and sulphite ions, iron (II) and irons interfere. The influence of the dissolved organic substances can be excluded by conversion of the manganese hydroxides into oxygen‐sensitive carbonates by subsequent addition of 4 cm3 ...
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...For this experiment, we will be looking at the effects of oxygen deprivation in cockroaches by putting petroleum jelly on the severed cockroach leg. The energy to operate the sodium potassium pump is created by ATP, and besides food we also need oxygen in order to produce ATP, making oxygen a necessity to humans and cockroaches alike. (Gage & Marzulla) Through this experiment, we may see the effects of not being able to breathe in oxygen. Oxygen deprivation affects us very negatively, as though we may be able to store up food for days, we cannot survive more than a dozen minutes without breathing. (Gage & Marzulla) Cockroaches breathe through spiracles, which appear as holes in the side of their body, and tubes called trachea deliver oxygen...
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