Stratospheric Ozone and CFCs
Nour Jafar Mrs. Elsen Chemistry 10 February 24, 2010 Stratospheric Ozone and CFCs In Earth's atmosphere, there are different layers. The troposphere is the innermost level. It is the first layer from Earth's atmosphere. Following the troposphere is the stratosphere, then the mesosphere, thermosphere, and finally the exosphere ("Importance of the Ozone Layer" par. 3). In the stratosphere, there is a thin layer of gas called ozone. "Ozone is a gas naturally present in the environment. It is similar to the gas oxygen," but ozone is a light blue tint (Morgan 4). Diagram Source: Draget.net Currently, the world is facing a global crisis. This crisis is the ozone layer is thinning, especially over Antarctica, causing an 'ozone hole' (Morgan 4). "In the early 1970s, scientists found that substances used in aerosol, or spray, cans damaged ozone molecules." The substances used in the spray cans were used as a propellant, making the spray can's mechanism work (Morgan 12). "Because of their chemical stability, low toxicity, and valuable physical properties, these chemicals, versatile and stable in the lower atmosphere, at least, have been extensively used since the 1960s as refrigerants, industrial cleaning solvents, propellants in aerosol spray cans, and to make Styrofoam." ("Stratospheric Ozone: Background Material" par. 7). The substances found in the spray cans are CFCs. CFC is
Enthalpy of Combustion Lab Report
22/9/2008 Dhruva Mahimtura Enthalpy of Combustion of Ethanol Aim: The aim of the following experiment is to determine the enthalpy change of combustion of ethanol when one mole of ethanol is burned completely with the help of a spirit lamp for a time period of one and a half minutes. Background: Specific Heat Capacity is the amount of heat required to raise the temperature of 1g of a substance by 1K. ? · Differs from substance to substance. ? · Water = 4.18 J g-1 K-1? · Ethanol = 2.4 J g-1 K-1 The data booklet value for the standard enthalpy of combustion of ethanol is -1371 KJ/mol. Apparatus: Instrument / Chemical: . Spirit lamp containing ethanol 2. Copper Calorimeter 3. Distilled Water 4. Stop Watch (?0.01s) 5. 1?50cm3 beakers 6. Retort Stand 7. Digital Thermometer (?0.1) 8. Digital Electronic Balance (?0.01g) 9. Stirring rod Method: . The mass of the spirit lamp containing ethanol is first determined accurately with the help of the digital electronic balance and is recorded as M1 (?0.01g). 2. Then a copper calorimeter is taken and the mass of the empty calorimeter is first determined. Then the calorimeter is filled with distilled water and the mass of the calorimeter along with water is then recorded. The two readings are then subtracted to
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Investigating Solutions. In this experiment the effect of concentration of different solutions will be investigated against conductivity The conductivity of an electrolyte solution is a measure of its ability to conduct electricity.
Investigating Solutions 29/1/11 In this experiment the effect of concentration of different solutions will be investigated against conductivity - The conductivity of an electrolyte solution is a measure of its ability to conduct electricity. The SI unit of conductivity is Siemens per meter (S/m) but can me also measured as microsiemens per meter (µS/m). Generally most of Ionic substances conduct electricity whilst molecular substances do not. This is because when ionic substances are dissolved; the electrons are free to move therefore carrying an electric charge. Research Question - What is the effect of concentration on conductivity in ionic substances? Hypothesis - I think that as the concentration increases the conductivity will also increase. I predict this because as there are more ions that can carry a charge and therefore conduct electricity. Also I think that CaCl2 will be the solution that will conduct the most electricity because it is more ionic than NaCl as it is in group 2 (looses more electrons) and AlCl3 shows some covalent properties which reduce the conductivity. Diagram - Equipment - * Lab Quest * Conductivity probe (set to a range of 0-2000 µS.m) * Utility clamp and stand. * Dropper bottle of distilled water * 100cm3 empty beaker * 400ml of 1M NaCl * 400ml of 1M CaCl2 * 400ml 1M AlCl3 * 100cm3 measuring cylinder Risk
Determining the Molar Mass of Volatile Liquid
Determining the Molar Mass of Volatile Liquid Aim: In this experiment the molar mass of an unknown volatile hydrocarbon liquid was determined by evaporation of the liquid and condensation of a defined volume of its vapor. Background: The molar mass of the volatile liquid was calculated from the number of moles and the mass of the sample. In order to get the number of mole of the volatile liquid, the ideal gas law was used. The moles of an ideal gas can be calculated with the ideal gas law: PV = nRT R represents the gas constant (8.314 J mol-1 K-1). n= PV / RT With this formula, we can determine the moles of the gas in a given volume of the glass ware (V). The molar mass can then be calculated with the moles of the gas and the molar mass formula. M = m / n Variables: Controlled Volume of volatile liquid Pressure of the room Room temperature Independent Temperature of hot water bath Dependent Mass of the condensed vapor of the volatile liquid Method for controlling variables: * The volume of the Erlenmeyer flasks used for the trials was determined by filling it with water to the overflow and measuring the volume of the water in a 250 cm3 graduated cylinder. * The volatile liquid was weighed on the same electronic balance. * The temperature of the water was measured in all runs with the same digital thermometer. * The atmospheric pressure was measured
IB IA: Gas Law Experiment - testing Boyles Law, Charles Law and Ideal Gas Law.
IB INTERNAL ASSESMENT - CHEMISTRY LAB REPORT. Objective: I. Investigating the effect of pressure on the volume of gas. II. Investigating the effect of temperature on the volume of gas. III. Studying the ideal gas equation. Apparatus: Ruler, opened end monometer, glass tube, thermometer, conical flask, beaker, mercury plug, retort stand, Bunsen burner. Materials: Rubber band, aluminum foil, ice, water bath, anti bumping granule Experiment 1 - Boyle's Law Hypothesis: The volume of gas is inversely proportional to its pressure. Variables: I. Independent: The gas pressure II. Dependent : reading of the ruler which represents the gas volume III. Constant: Temperature. Result: Reading on the clip: 47.30 ± 0.05 Reading where mercury of both opening has the same level: 34.00 ± 0.05 Volume of gas under atmospheric pressure Patm: 13.30 ± 0.05 Mercury level in closed end tube(mm) ± 0.5 mm Mercury level in opened end tube(mm) ± 0.5 mm Difference in height = P hg Pressure of gas, P (P = Patm + P hg ) Height of gas ± 0.5 mm Volume of gas ± 0.5 mm PV 00.0 63.00 63 96 238.0 238.0 46648 14.0 58.00 44 77 243.0 243.0 43011 17.0 47.00 30 63 248.0 248.0 40424 21.0 34.00 3 46 253.0 253.0 46938 44.0 32.00 2 45 258.0 258.0 37410 *Assuming that the diameter of the tube is constant, then the volume of the gas directly
Evidence of Chemical Reactions Lab
Evidence of Chemical Reactions Lab (no design) Malcolm McCulloch Purpose The purpose of this lab is to investigate some of the kinds of evidence that are seen for chemicals changes and reactions. Data Collection (Raw Data) Table 1 Temperature values ± 0.5ºC Test Reactants Initial Observations Observations at 5mins Observations at 20mins HCl (clear liquid) NaOH (clear liquid) Temp: 23.0ºC No visible reaction. Temp: 26.0ºC No visible reaction. Temp: 25.0ºC No visible reaction. Temp: 24.0ºC 2 HCl (clear liquid) CaCO3 (white solid) • CaCO3 sunk to bottom • bubbles on its surface • fizzing noise • still bubbling • still making noise • the liquid looks whitish from so many bubbles • still bubbling • still making noise • bubbles appearing so rapidly that they form a sort of swirling current 3 NaCl (clear liquid) AgNO3 (clear liquid) • AgNO3 turns to consistency of wet tissue paper instantly when drop hits surface • sinks to bottom in such a form • precipitate at bottom • crystal formed floating on the surface of the NaCl • more precipitate at the bottom • crystal has decreased in size (fallen) 4 Cu(NO3)2 (blue liquid) Zn (silver metal) • the zinc blackens • still black • small bubbles on it • liquid more turquoise than before • liquid now a deep turquoise 5 NaOH (clear liquid) Cu(NO3)2
Chemistry Lab Report. Investigation of the Effect of Heat on Vitamin C
Chemistry Lab Report 20.04.2009 Investigation of the Effect of Heat on Vitamin C Background: Vitamin C, or ascorbic acid, is a water-soluble vitamin of molar mass 176 g/mol. It is known that cooking foods destroys the vitamin C. Ascorbic acid also reacts with free iodine in a 3 to 1 ratio. This free iodine is formed by mixing KIO3 with acidified KI. Research Question: How is vitamin C affected by short and extended exposure to high temperatures? Hypothesis: Because cooking food destroys vitamin C, extended exposure to high temperatures will destroy ascorbic acid, and the longer the duration the less vitamin C that will survive. At lower temperatures, the vitamin C should be destroyed to a degree proportionate to the temperature. Procedure: Approximately 15 cm3 of 0.1966 M ascorbic acid was placed in a 50-cm3 flask. Then the flask was placed on a hot plate, heated up to 50oC, and kept there for two minutes. Then about 5 cm3 of the solution (accurately massed) was placed in a 25-cm3 beaker. Then 15 drops of 0.10 M KI, 25 drops of 1.0 M HCI, and 10 drops of 5% soluble starch was added, and the solution was stirred. Then a dropper was filled with .01 M KIO3 and was added to the solution until a dark blue/black color appears (starch-iodine indicating there is no more ascorbic acid to react) and remains even after stirring. Then the KIO3 dropper was weighed
Empirical Formula of a Hydrate-CE
Lab#7: Empirical Formula of a Hydrate-Laurie Chan 11/13/2008 Conclusion and Evaluation: Aspect 1 Based on the interpreted data of group "A", the empirical formula of aluminum chloride did not stay the same. The expected empirical formula was. In group "A" the empirical formulas are as followed... Group Name Empirical formula Laurie & Jordan Rica, Victoria & Stephanie Vince & Josh Jane & Kaityln So, as a group, we all had a different outcome of the empirical formula but the percent composition of water is the same for all. 11.2% for hydrogen and 88.8% for oxygen as shown in table #7.3. A random error would be the measurement of the hydrate crystal. A scoopula was used to measure 3g. Also another one would be the electronic balance having an uncertainty of ±0.001g. A systematic error would be heating the evaporating dish through a wire mesh instead of a clay triangle. You notice that the theoretical yield and experimental yield values are shown in a pie graph. Both of the pie graphs are the exact same as both percentages are 11.2% and 88.8%. In these pie graphs, neither trends nor patterns apply. Aspect 2 The procedural weaknesses are stated above. For example the measurement of the hydrate crystal would've affected the lab. There wasn't an accurate measurement so that could've affected the weight of the final product or the reaction of the product. Another
Chemistry experiment
Chemistry Experiment ------ Industrial Discharges My experiment is about Industrial Discharges. The main idea of my experiment is to show the disadvantages of Industrial Discharges. According to my research, I found that factories letting out the polluted water to the sea, oceans and rivers. Polluting water causes many chemical changes in the water. For example, there is not enough air in the water, the fishes and plants don't have much air in the water, so they died. This is a serious problem, not only because human eat fish in the water, but also damage the balance of the environment. My experiment includes: * 2 (150ml) beakers * 50ml water * 50ml polluted water (Chemical changes in the water) * Plants which grow in the water To make my experiment more accurately, I keep the weigh of the plants (I count the numbers of leaves), the same amount of water and the same size of beakers. The details are below: Dates Colour of leaves Beaker1 Colour of leaves Beaker2 Alive leaves in Beaker 1 Alive leaves in Beaker 2 22/11/07(Thursday) All Green All Green 22 22 23/11/07(Friday) All Green All Green 22 22 26/11/07(Monday) All Green 21 Green 1 Yellow 22 21 27/11/07(Tuesday) All Green 21 Green 1 Yellow 22 21 28/11/07(Wednesday) 21 Green 1 Yellow 20 Green 2 Yellow 21 20 29/11/07(Thursday) 21 Green 1 yellow 20 Green 2 Yellow 21 20