Food and Chemical Toxicology 45 (2007) 1650–1661 www.elsevier.com/locate/foodchemtox A comparison of chemical‚ antioxidant and antimicrobial studies of cinnamon leaf and bark volatile oils‚ oleoresins and their constituents q Gurdip Singh b a‚* ‚ Sumitra Maurya a‚1 ‚ M.P. deLampasona b‚ Cesar A.N. Catalan b a Chemistry Department‚ DDU Gorakhpur University‚ Gorakhpur 273 009‚ India Instituto de Quimica Organica‚ Universidad Nacional de Tucuman‚ Ayacucho 471‚ S.M. de Tucuman
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Calculating the Enthalpy Change of Reaction for the Displacement Reaction between Zinc and Aqueous Copper Sulphate Data Collection and Processing Observations: * Drops of water left on the inside of the measuring cylinder * Hole in the lid‚ possible escape route for gas or splash-back * The polystyrene cup felt warm during the reaction By extrapolating the graph we can estimate what the rise in temperature would have been if the reaction had taken place instantaneously. I can
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EXPERIMENT 1: Aim: To range the metals copper‚ lead‚ silver and zinc together with hydrogen. Start with the strongest reducing agent. Hypothesis: The nobler a metal is‚ the worse reducing agent. Apparatus/requirements: Sandpaper‚ strips of; zinc‚ lead‚ silver and copper‚ solutions containing aqueous; Zn2+‚ Pb2+‚ Cu2+ and Ag+ ions (0.2 M)‚ hydrochloric acid (5.0 M)‚ emery paper‚ test-tubes. Method: Burnish the three metal strips to get a shiny surface‚ after drop a drop of each of the metal
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Oxygen (O) Human beings obtain this element from the air. It enters a person’s bloodstream through the lungs. The blood carries oxygen to the cells of the body. In the cells‚ oxygen combines with chemicals obtained from food. Energy produced during this process makes it possible for each cell to perform its function in the body. Also‚ oxygen atoms are present in water and water is essential to all life. It is present in many organic compounds. While oxygen is necessary for life‚ oxygen as ozone
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1. Gather all the equipments needed. 2. Measure 50ml of HCL in a 250 ml measuring cylinder and pour it into a flask‚ then measure 50ml of HCL again and pour it into the second flask. 3. Measure the 50ml of KOH in a measuring cylinder. Repeat it again in another measuring cylinder. 4. Attach both of the burette clamps to both of the burette stands and clamp the burette at a certain level so that it can fit a flask underneath. 5. Then‚ place a funnel on top of each burette. 6. Place a flask underneath
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dissolving the zinc core and leaving behind the copper coating. We will figure out the percent composition from the mass of copper and zinc using titration and precipitation. Procedure: 1) First dissolve the zinc core of a penny and leave copper covering intact by applying four notches in the coin using a triangular file. 2) Place the penny in a 50 mL of a pre-determined concentration of HCl solution overnight. 3) Then determine the percent copper from the mass of copper. 4) Find the percent of zinc by precipitation
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copper and zinc in a post 1982 penny? - 97.5 % Zinc and 2.5 % Copper 3. How many grams of copper and zinc are in a post 1982 penny? - (2.496 x 0.975) = 2.43 g of Zinc (2.496 x 0.025) = 0.062 g of Copper 4. How many moles of copper and zinc are in post 1982 pennies? (2.43 g Zn x 1 mol Zn) / 63.38 g Zn = 0.037 mol Zn (0.062 g Cu x 1 mol Cu) / 63.54 g Cu = 0.00097 mol Cu 5. Write a balanced reaction of zinc with HCl. - Zn (s) + 2HCl (aq) ZnCl2 (aq) + H2 (g) 6. How many moles of HCl are needed
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decrease in oxidation state. If zinc completely reacts with HCL‚ then the theoretical yield of copper should be equivalent to the actual yield. Purpose: In this lab‚ we will determine the percent composition of a modern (post-1982) penny by using a strong acid to react and dissolve the zinc core‚ leaving only the copper coating. Once only copper remains‚ we will compare its mass to the entire mass of the penny to determine how much of a penny is copper and how much is zinc. 1. Obtain one 50.0 mL beaker
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the percent copper and zinc in pennies through titration and gravimetric techniques: 1. What is the weight of a post 1982 penny? 2. What is the percent copper and zinc in a post 1982 penny? 3. How many grams of copper and zinc are in a post 1982 penny? 4. How many moles of copper and zinc are in post 1982 pennies? 5. Write a balanced reaction of zinc with HCl. 6. How many moles of HCl are needed to react completely with all of the zinc in a post 1982 penny?
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percent of zinc is 97.5% leaving only 2.5% copper. The amount of Zinc in a post 1982 penny is 2.437 grams‚ and the amount of copper is 0.062 grams. Along with all of this we must know the amount of moles of each. To find the amount of moles we must solve for them: Zinc = (2.4375g / 1) X (1 / 65.38g) = 3.73 X 10-2 moles Copper = (0.0625g / 1) X (1 / 63.546g) = 9.835 X 10-4 moles The balanced equation for zinc and HCl is Zn + 2HCl = 1H2 + 1 ZnCl2 H=1‚ Zn = 65.38‚ Cl=35.45 Molar Mass of HCl = 101.83
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