the tea bags that were provided‚ and then recrystallize the caffeine. The solvents used in the experiment were an aqueous sodium carbonate and dichloromethane (DCM). Anhydrous calcium chloride pellets were used to dry the solution and emulsion layer and the DCM was then decanted. After washing the anhydrous calcium chloride pellets with more DCM‚ the solvent was evaporated‚ leaving greenish-white crystalline caffeine residue weighing about .25 mg. In order to recrystallize the caffeine‚ we used
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How fast is your reaction? Part 1 – How temperature affect the rate of reaction Chemical equation Magnesium + hydrochloric acid → magnesium chloride + hydrogen Mg + 2HCL → MgCl2 + H2 Graph Conclusion and questions 1. What factors/variables did you keep the same in this experiment? * We kept the same volume of hydrochloric acid (10 cm3) and the magnesium ribbon (5cm) because that way we could get a fair test experiment. We also repeated
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the color that the fireworks have because the colors change in the electromagnetic spectrum. As observed by my data all of the salt’s wavelengths correspond to the specific color that they burned on the electromagnetic spectrum. For example‚ Copper Chloride burned green when placed on the fire. This corresponds to the color green on the electromagnetic spectrum‚ which is around 525nm wavelength. However‚ this energy was not produced by the chemical reaction; it was only transformed by
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weighing dish and Na2CO3 _1.2_g Net mass of the Na2CO3 _0.7__g Step 6: Mass of filter paper _1.0_g Step 10: Mass of filter paper and dry calcium carbonate __1.5_g Net mass of the dry calcium carbonate __0.5__g (This is the actual yield) Step 11: Show the calculation of the theoretical yield of calcium carbonate. 0.00680 moles CaCO3 x 100 g CaCO3 1 mole CaCO3 = 0.68g CaCO3 Show the calculation of the percent yield. Actual yield/Theoretical yield
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Making Molar Solutions and Dilutions Objectives: After performing this lab‚ the student should be able to: • Calculate grams of solute and correctly prepare a molar solution. • Prepare parallel and serial dilutions using C1V1 = C2V2 • Distinguish a parallel dilution from a serial dilution. • Determine whether a parallel or serial dilution should be used in a given situation. • Use a microcentrifuge to make a pellet. Making Molar Solutions and Dilutions A major job of any biotechnician
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is directly related to the solubility of iodine in water in this case. 2. Ammonium chloride will be more soluble in hot water as in an endothermic reaction‚ increasing the temperature (which is the same as adding heat - one of the reactants) will cause the position of equilibrium to shift towards the products to compensate for the change. More products are a result of increased solubility of Ammonium Chloride with water when temperature is increased. Post Lab Questions 1. CoCl42- ions are
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& Analysis: Metals & Solutions Prior to Reaction Post Reaction Analysis Aluminum & Copper (II) Chloride -Blue translucent liquid -Small silver ball -Grew ten times original size -Rust Color -Clear transparent liquid A buildup of residue formed and the clear solution became cloudy with flaky matter. Iron & Magnesium Chloride -Clear transparent liquid -Silver nail - No Reaction -No reaction Zinc & Lead (II) Nitrate -Clear transparent liquid -Silver
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freshwaters • Define where freshwaters lie on a spectrum of increasing concentrations of dissolved constituents in water. • On average‚ which ions are most prevalent in freshwaters (in comparison with sea water): sodium‚ chloride‚ calcium‚ bicarbonate? • What are hypersaline lakes? Describe their variable compositions. • In what units are constituents in freshwater measured as compared with seawater: grams per litre or milligrams per litre? • Geological
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Write up for Qualitative Analysis 1. Introduction- This experiment is for qualitative analysis so we are trying to find out what is in a substance. In this case we are using the flame test to try and discover what is in 4 unknown sample solutions that we have been given this is done by cross referencing the colour of the flame with 6 known solutions we test beforehand. Aim- In this experiment we are attempting to distinguish what substances are in the 4 unknown solutions by cross referencing
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Surname Centre No. Initial(s) Paper Reference 4 3 3 5 Candidate No. 2 H Signature Paper Reference(s) 4335/2H Examiner’s use only London Examinations IGCSE Team Leader’s use only Chemistry Paper 2H Higher Tier Tuesday 6 November 2007 – Morning Time: 2 hours Question Leave Number Blank 1 2 3 4 5 Materials required for examination Nil Items included with question papers Nil 6 7 8 9 Instructions to Candidates In the boxes above‚ write your centre number‚ candidate number‚ your surname
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