...Determining the Empirical Formula of Magnesium Oxide Lab Purpose The purpose of this lab was to determine the percent composition and empirical formula of magnesium oxide. Hypothesis If a strip of pure magnesium metal reacts with oxygen in the air to create magnesium oxide, then the molecular formula will be MgO. The percent composition for magnesium oxide would be 60.31% magnesium and 39.69% oxygen. Apparatus Refer to attached sheet Procedure Refer to McGraw-Hill Ryerson Chemistry 11, page 212-213. 4. The mass of the empty crucible and lid was recorded. The strip of cleaned magnesium was added to the crucible. The mass of the crucible, lid and magnesium was recorded. 10. The substance remained in the crucible, above the flame for an extra five minutes on high heat, after the water had evaporated completely. Results Mass of clean, empty crucible and lid | 26.73g | Mass of crucible, lid, and magnesium | 26.87g | Mass of crucible and magnesium oxide | 26.95g | Analysis 1. a) We used 0.14 g of magnesium in the reaction. b) 0.22 g of magnesium oxide was produced. c) 0.08 g of oxygen reacted with the magnesium (0.22 g – 0.14 g = 0.08 g). d) Refer to “Determining the Empirical Formula of Magnesium Oxide Lab Solutions” sheet e) Element | % | m (g) | M (g/mol) | n (m÷M) | ÷ by | Ratio | Magnesium | 63.63 | 63.63 | 24.31 | 2.617441382 | 2.273125 | 1 | Oxygen | 36.37 | 36.37 | 16.00 | 2.273125 | 2.273125 | 1 | Since the ratio is 1:1,...
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...the external air and the body. The lungs are the primary organ of the respiratory system that performs this function. The lungs take up a large portion of the thoracic cavity and are actually attached to the surface of the thoracic cavity by a sticky pleural membrane. The pleural membrane produces a liquid called surfactant that allows the lung to stick to the ribs. On occasion, air gets caught in the space between the lungs and the thoracic cavity and can cause the lungs to collapse. This may be caused by trauma, infection, or can occur spontaneously. The amount of oxygen needed by the body, and carbon dioxide produced by the body, can vary greatly depending on an individual’s activity level. Exercise can increase the need for energy produced by cellular respiration, and therefore the oxygen demanded by the body, by 25 times. An increase in the rate of respiration can meet this demand. https://www.lung.ca/children/images/grades7_12/the_r espitatory_system.gif Process of Respiration Step Process The intercostal muscles contract, pulling the ribs up, and the diaphragm contracts and 1 2 3 4 5 6 7 8 9 10 moves down, pulling air into the body through the mouth or nostrils. Air passes through the nasopharynx or oral pharynx through the epiglottis, which prevents food from entering the trachea. The trachea contains tiny hair-like cilia and mucus that catch any particles in the air that could be harmful to the lungs, and moves them back up the trachea to be spit out. Air moves down...
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...PURPOSE In this experiment, you will show how redox reactions can be used to quantitatively determine the amount of oxidizing agent in liquid hypochlorite household bleach. There are two oxidation-reduction reactions for determining the oxidizing capacity of bleach. Initially an excess of iodide ions are added to a bleach solution. The iodide ions are oxidized to iodine after the solution has been acidified. Starch is added to the resulting iodine solution as an indicator. The solution is then titrated with sodium thiosulfate until the color of the solution changes indicating the endpoint of the reaction. Data collected from the titrations will be used to calculate the mass of the sodium hypochlorite in an unknown solution of bleach. Given the original mass of the unknown solution and the calculated mass of the sodium hypochlorite in the unknown solution, the percent by mass of the sodium hypochlorite can be determined. The oxidizing capacity of the unknown bleach is effectively the percent by mass of the sodium hypochlorite in the unknown bleach sample. OJECTIVES 1) Titration of a sample of bleach with thiosulfate. 2) Determining the end point of the titration with starch indicator. 3) To determine oxidizing capacity of bleach by determining the percentage by mass of the bleach that is sodium hypochlorite. 4) Balance and summarize the two redox reactions to determine the overall chemical reaction that occurs during the titration. PRINCIPLES Oxidizing Capacity of Bleach ...
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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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...AP Biology Exam Review: Lab Essays At least one essay (FRQ) on the exam will be based on an AP laboratory. To prepare for this question, review the objectives for all twelve laboratory exercises. The College Board does not necessarily expect that you have completed that lab, but rather that you have investigated the objectives of the lab. You may be asked to “design an experiment to determine….” You don’t necessarily need to create a new lab; if you have done an activity that would answer the question, simply describe it. For a good response, you should include the following. 1. State a hypothesis [as an “if…..(conditions), then….(results)” statement] Be sure your hypothesis is testable. 2. Identify the variable factor. 3. Identify the control. Be certain to explain the control for the experiment. 4. Hold all other variables constant. 5. Manipulate the variable. 6. State how you would measure the results. 7. Discuss the expected results. Relate the results to your hypothesis. 8. Include steps to replicate or verify. You may be asked to graph data. Be sure to use a graph that is appropriate for you data. Bar graphs are used when data points are discrete (not related to one another), while line graphs are used with the data are continuous. If there is a data point at zero, be certain to extend your line to 0, but do not extend the line to 0 if there is no data point at zero. Other points to keep in mind: ...
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...comprising Earth and seeks to understand the many processes that operate beneath and upone its surface. Historical geology is to understand the origin of Earth and the evolution of the planet through its 4.6 billion year history. Oceanography- Is not actually a separate and distint science. Rather is involves the application of all sciences in a comprehensive and interrelated study of the oceans in all their aspects and relationships. It intergrates chemistry, physics, geology, and biology. Meterology- is the study of the atmosphere and the processes that produce weather and climate. Like oceanography, meterology involves the application of other sciences in an intergrated study of the thin layer of air that surronds eather. Astronomy- the study of the universe- it useful in determining the orginis of our own environment. (Page 4-5) * Be able to name and define each of the earth’s “spheres” (geosphere, hydrosphere, atmosphere, biosphere). Hydrosphere- is a dynamic mass of water that is continually moving, evaporationg fomr the ocenas to the atmosphere, precipitation to the land, and flowing bacj to the ocean. (page 6) Atmosphere- Earth surrounded by a life-giving...
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...well the lungs take in and release air and how well they move gases such as oxygen from the atmosphere into the body's circulation. How the Test is Performed Spirometry measures airflow. By measuring how much air you exhale, and how quickly, spirometry can evaluate a broad range of lung diseases. In a spirometry test, while you are sitting, you breathe into a mouthpiece that is connected to an instrument called a spirometer. The spirometer records the amount and the rate of air that you breathe in and out over a period of time. For some of the test measurements, you can breathe normally and quietly. Other tests require forced inhalation or exhalation after a deep breath. Sometimes you will be asked to inhale the substance or a medicine to see how it changes your test results. Lung volume measurement can be done in two ways: * The most accurate way is to sit in a sealed, clear box that looks like a telephone booth (body plethysmograph) while breathing in and out into a mouthpiece. Changes in pressure inside the box help determine the lung volume. * Lung volume can also be measured when you breathe nitrogen or helium gas through a tube for a certain period of time. The concentration of the gas in a chamber attached to the tube is measured to estimate the lung volume. To measure diffusion capacity, you breathe a harmless gas, called a tracer gas, for a very short time, often for only one breath. The concentration of the gas in the air you breathe out is measured. The difference...
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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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...experience the effects of extreme pressure and they must have specific adaptations that enable them to survive in such harsh environments. Temperature Variations – Usually in an aquatic environment there are minimal temperature variations to that compared with terrestrial environments. The temperature variations also depend on the size of the body of water; a large body of water will experience much less temperature variations than a smaller body of water. Also, as depth increases the temperature of the water decreases. Availability of gases – in water the availability of gases depends on factors such as temperature, depth and turbulence. Hot water holds much less oxygen than cold water. The availability of gases also depends on the rate of diffusion which is much slower in water than it is in air. Also, as the depth of the...
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...CERTIFIED SAFETY AND HEALTH EXAMINATION SAMPLE QUESTIONS The Certified Safety and Health Examination Practice Items are intended to familiarize prospective examinees with the style and format of the CSHM examination questions. There are 36 objective practice items contained in this Guide, whereas the actual CSHM examination contains 150 objective items. The 150 test items will have the following weighted breakdown. Management and Leadership Principles and Methods (21% of test/32 questions) Risk Identification, Management and Control (35% of test/52 questions) EHS Operations, Programs and Applications (28% of test/42 questions) Incident Investigation and Performance Evaluation (16% of test/24 questions) Exams administered outside the United States will be in US English. Exam questions for candidates in this category will contain fewer questions that pertain only to the United States (i.e. OSHA, NIOSH, etc.) None of these practice items will be found on the actual CSHM certification examination. These practice items are only meant to be representative of the type of items found on the certification examination. Following the practice items is a quick scoring key and the rationales for the answers. Remember to select the BEST answer. Good luck! I. GENERAL AND BUSINESS MANAGEMENT 1. A hazard analysis can be used to evaluate a potential hazard; what other information should be considered? a. b. c. d. Injury reports Statistical data Risk assessment Fatality investigations ...
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...average atomic mass Atomic mass is the mass of an atom in atomic mass units (amu). One amu is defined as 1/12 of one C-12 atom. The C-12 isotope has a mass of exactly 12.000 amu. The C-12 isotope provides the relative scale for the masses of the other elements. Average atomic mass is the value reported on the periodic table, which takes into account the various isotopes of an element and their respective frequencies. To calculate the average atomic mass of an element, add up the different masses of the isotopes (using amu) multiplied by each isotope’s abundance (percent occurrence in nature divided by 100). Average atomic mass of element x = (isotope1 in amu × abundance1) + (isotope2 × abundance2) + (isotopen × abundancen) Example 1. Determining average atomic mass. The natural abundance of the C-12 isotope in nature is 98.90% and the C-13 isotope is 1.100%. What is the average atomic mass reported on the periodic table for the element carbon?...
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...ENERGY TECHNOLOGY S.JITENDRA PAL Department of Chemical Engineering National Institute of Technology Karnataka Surathkal-Karnataka. Assistant Professor Fundamentals of energy and its impact on society and the environment. What is energy? • Energy :defined as the ability or capacity to do work. Energy is measured in BTU (British Thermal Unit) or Joule • According to Max Planck, energy is defined as the ability of a system to cause external action. • The term energy carrier – thus a carrier of the above defined energy – is a substance that could be used to produce useful energy, either directly or by one or several conversion processes • In this respect the following forms of energy are distinguished: mechanical energy (i.e. potential or kinetic energy), thermal, electric and chemical energy, nuclear energy and solar energy etc. Why Energy is needed ? • Think about how you use energy every day. You wake up to an alarm clock. You take a shower with water warmed by a hot water heater. You listen to music on the radio as you dress , u eat breakfast….. And so on……. • Food items, medicines, groceries, the accessories which we use, Cosmetics, electronic appliances, lighting, heating cooling, • Everything needs energy in direct or indirect way Why Energy is needed ? Various sectors of economy- Industry, residential, commercial, transport • Industry- Petroleum Refining , steel, cement, chemical, metal, paper, pharmaceuticals, mining etc • Transportation,-automobile...
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...The Study of Interactions between mussels and their Environment, as well as, between different species of intertidal organisms within a particular Intertidal Community By Arlene Reynolds California State Polytechnic University, Pomona, CA . Abstract. (The relationship between mussels and intertidal organisms within a particular community in the intertidal zone is a great example of the competitive exclusion principle. The alternative hypothesis for this study would be that there is a direct relationship between organisms due to interspecific competition, Introduction: California mussels (Mytilus californianus) are abundant where there is surf along the outer coast. They form massive beds, sometimes several meters across, on surf exposed rocks and wharf pilings in the upper middle intertidal zone and offshore, up to 24 meters deep. Like barnacles, mussels like to gather in dense clusters in the middle intertidal zone. Mussel beds are often large enough to be a home to many other creatures, like snails and worms. California mussel beds accumulate a gritty mixture of sand and bits of shell which provide a home for a various assemblage of animals including a number of polychaete worms, snails, crabs and a blackish sea cucumber. The Ochre sea stars are California mussels' main predator. Ochre sea stars affect the distribution of the mussels because the sea star generally occurs lower on the shore than the mussels and moves up to feed during high tide. Mussels are also eaten...
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...1 ESSAYS ON SUSTAINABILITY Thirteen Challenging Essays for Earthlings By Peter E. Black, 2008 Wheels and Water .......................................................page 1 Water and Humans on Planet Earth ................................... 2 Climate, Weather, and Global Warming ............................. 3 A Catastrophic Loss of Species ......................................... 4 The Naked Truth................................................................... 5 Asymmetrical Resource Distribution ................................. 6 Stormwater and Groundwater Runoff ................................ 7 Economy, Energy, Environment ......................................... 8 Drill in the ANWR? No Way! ............................................... 9 The Wonder of Water ......................................................... 10 Buffering Sands of Time.................................................... 11 Ecology and Civilization .................................................... 12 With a Bang, not a Whimper.............................................. 13 © 2008 Peter E. Black, PhD (US Copyright Registration TXu 1-580-484, July 13, 2008 as “Conservation is the Cornerstone of Sustainability”) Distinguished Teaching Professor of Water and Related Land Resources, Emeritus, State University of New York, College of Environmental Science and Forestry, 1 Forestry Drive, Syracuse, NY 13210 peblack@esf.edu and www.watershedhydrology.com Essays on Sustainability Thirteen Challenging...
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...The development of a national system of health care in the United States has remained a major topic of debate throughout the United States, especially since the 1980s. Healthcare costs in the United States have risen dramatically during the past 40 years, due in part to longer average life spans, which give rise to greater costs because older citizens require greater care, and the employment of technologies that extend the life of patients, which generally results in greater spending. Insurance costs have likewise increased dramatically, and a relatively large percentage of U.S. citizens and other residents are uninsured or underinsured. According to information from the census bureau in 2001, 41.2 million Americans, constituting 14.2 percent of the population, did not have Health Insurance. The healthcare system is largely controlled by the free market, which is believed to provide limitations on how much physicians and other specialists can charge to their patients. However, many critics of the current system, including organizations composed of physicians, note that the system has become largely bureaucratic and that cost-cutting measures and pressures caused by competition and the need for profit have reduced the effectiveness of medical practice. Despite these problems, many commentators have not been able to agree as to the proper level of control that state or federal governments should have over health care. Following World War II, the number of Americans that had...
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