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| MASS, VOLUME AND DENSITY MEASUREMENTS |
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Experiment 1. Calibration Of A 10 ml Volumetric Pipet The volume of a 10 ml volumetric pipet will be determined by weighing the water transferred by the pipet. The density of water will be used to convert to the mass of water to a volume of water. Experiment 2. Density Determinations Using Various Methods To Measure Volume The densities of brass and aluminum will be calculated from mass and volume measurements. The results will be used to determine the composition of a mixed brass and aluminum cylinder and the volume of empty space within a hollow cylinder. Volumes will be determined by three different methods: geometrically, by water displacement, and by the use of a pycnometer. |
| MEASURING NUMBERS OF ATOMS OR MOLECULES |
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Experiment 3. Determination of Amount of Vitamin C in Personally Chosen Sample by Redox Titration The amount of extractable ascorbic acid (vitamin C) in a natural or commercial product will be determined by extracting the ascorbic acid from a solid or liquid, followed by redox titration of the vitamin C using DCP. The DCP is colored until it reacts with Vitamin C. The DCP is added to the sample until color remains, indicating that all the Vitamin C in the sample has been consumed by the added DCP. This amount of added DCP is related to the amount of Vitamin C in the sample. Experiment 4. Determination of the Molar Mass of an Unknown Gas The ideal gas law will be employed to determine the molecular weight of an unknown gas by collecting it in a known volume at known temperature and pressure and weighing it. The Molar Mass will be the mass divided by the number of moles, which are related to the temperature, volume, and pressure of the gas by the ideal gas law. Experiment 5. Determination of the Empirical Formula of Magnesium Oxide Two experiments will be done to determine the empirical formula of magnesium oxide, the result of burning magnesium metal in air. First, the ideal gas law will be used to determine the molar mass of magnesium. Then, magnesium will be burned and the change in mass upon combustion will be used to determine the empirical formula of the product, magnesium oxide. Experiment 6. Determination of the Molar Mass of an Unknown Solid by Freezing Point Depression The freezing point depression constant for cyclohexane will be determined by measuring the freezing points of a series of solutions in which p-dichlorobenzene is dissolved in cyclohexane. The freezing point of a solution containing a known weight of an unknown organic solid will be measured, and from that solution's freezing point depression, its molecular weight will be calculated. Experiment 7. Determination of Amount of Acid Neutralized by an Antacid Tablet using the method of Volumetric Analysis by Back Titration The number of moles of acid that can be neutralized by a single tablet of a commercial antacid will be determined by dissolving the tablet in a known (excess) amount of acid. The resulting solution will then be titrated with base to determine the amount of acid not neutralized by the tablet. The moles of acid neutralized by the tablet is the initial moles of acid minus the moles of acid neutralized in the titration. |
| SPECTROSCOPIC STUDIES OF ATOMS AND MOLECULES |
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Experiment 8. Determination of Emission Series and emitting and final quantum states for the Visible Hydrogen Atom Emission The relationship between color of visible light and wavelength and frequency of the light will be determined by using a Spec 20 spectrometer. The visible emission spectrum of atomic hydrogen will be analyzed in a spectrometer. The principal quantum number for the final state of the atom will be determined graphically as well as the quantum number of the emitting states. A numerical value of the Rydberg constant will also be extracted from the graph. Experiment 9. Determination of Allura Red Concentration in Mouthwash The spectral profile of allura red will be obtained by measuring the transmittance of visible light with a Spec 20 spectrometer. The wavelength of light that is absorbed the strongest by allura red will be determined and a Beer's law plot of absorbance versus concentration will be constructed by making a series of volumetric dilutions from a stock solution of known concentration. The Beer's law plot will then be employed to determine the concentration of allura red in a sample of commercial mouthwash. |
| THERMODYNAMICS |
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Experiment 10. Determination of Heats of Transition and Reaction and Specific Heats A simple calorimeter will be made and calibrated. It will be used to determine the heat of fusion of ice, the specific heat of a metal, and the heat of a couple of chemical reactions. These heats of reaction will be used with Hess's law to determine another desired heat of reaction. Experiment 11. Spectroscopic Determination of an Equilibrium Constant The equilibrium for the reaction of iron (III) with thiocyanate to yield the colored product, iron (III) thiocyanate, will be studied and its equilibrium constant determined spectroscopically using the Spec 20 UV-visible spectrometer. The spectral profile of iron (III) thiocyanate will be obtained to determine the wavelength of light absorbed most strongly by the product. A Beer's law plot will be made for iron (III) thiocyanate. Using a set of different starting concentrations and measuring the concentration of iron (III) thiocyanate spectroscopically, the equilibrium constant for the reaction will be determined. Experiment 12. Determination of the Solubility Product for Calcium Hydroxide A saturated solution of Ca(OH)2 will be made by reacting calcium metal with water, then filtering off the solids. The concentration of dissolved Ca(OH)2 will be determined by acid-base titration with standardized HCl solution. The value of Ksp for Ca(OH)2 will be calculated from its solubility. Experiment 13. Characterization of an Unknown Acid The titration curve of an unknown weak acid with a strong base will be determined by using a pH meter. From the titration curve, the equivalence point, which is related to the molar mass, and the pKa of the acid will be found. The melting point of the solid acid will be taken. From the experimental values of molar mass, pKA, and melting point, choosing the appropriate compound from a list of possible weak acids will identify the unknown acid. Experiment 14. Electrochemistry and the Nernst Equation The values of E0 for some standard reactions involving metals and their ions in solution will be determined using a voltmeter. Dependence of the cell potential on ion concentration will be studied using a series of concentration cells. The solubility of silver chloride will be determined by measuring the voltage of a saturated solution against a standard solution of Ag+ ions. From the solubility, the value of Ksp for AgCl will be calculated. |
| RATES OF CHEMICAL REACTIONS |
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Experiment 15. Characterization Of The Rate Properties Of An Iodide Oxidation Reaction The rate of the peroxodisulfate iodide clock reaction will be determined using various concentrations of reactants. From the rate, the order of the reaction will be obtained for both of the reactants. The rate will be measured at three additional temperatures and the Arrhenius equation used to calculate the activation energy and the pre-exponential factor for the reaction. |
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