CHEM Density Determinations Formal Lab

CHEM Density Determinations Formal Lab - Experiment No 3...

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Experiment No. 3 – Density Determinations Chemistry 1411 PO5 – General Chemistry 1 South Texas College Spring Term – 2016 Objective :
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Density is an important property of matter, and may be used as a method of identification. In this experiment, you will determine the densities of regularly and irregularly shaped solids as well as of pure liquids and solutions. Materials : A). Rectangular block of wood Sample of metal pellets Distilled water 100 mL graduated cylinder Digital scale B). 25 mL graduated cylinder Distilled water Thermometer Digital scale Unknown liquid C). 100 mL graduated cylinder 25 mL of 5%, 10%, 15%, 20%, and 25% composition of sodium chloride Distilled water Thermometer Summary of Procedures: A). Determination of the Density of Solids Obtain a regularly shaped solid, and record its identification number. The regularly shaped solid used in this lab was a rectangular block of wood. Using a ruler, determine the physical dimensions of the solid such as length, width, and height in centimeters. Using the physical dimensions, calculate the volume of the solid. Obtain a sample of metal pellets and record its identification code number. Weigh a sample of the metal of approximately 50g, but record the actual mass of the metal from weighing the sample on a digital scale. Obtain a 100 mL graduated cylinder and add approximately 50 mL of water. Record the exact volume of water in the cylinder. Carefully pour the sample of the metal pellets you just weighed into the graduated cylinder. Stir the cylinder to ensure that there are no air bubbles trapped among the metal pellets. Read and record the level of the water in the graduated cylinder, making your determination to the precision permitted by the calibration marks of the cylinder. Assuming that the metal sample does not dissolve in or react with water, the change in water levels represents the volume of the metal pellets. Calculate the density of the unknown metal pellets. Blot the metal pellets dry when you are finished with them and return the pellets to your instructor.
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B). Density of Pure Liquids After carefully cleaning and drying a 25 mL graduated cylinder, weigh it and record the data in grams. Add distilled water to the cylinder so that the water level is above the 20 mL mark but just below the 25 mL mark. Using a thermometer, determine the temperature of the water in the cylinder. Reweigh the cylinder with water in it and record the weight. Determine the exact volume of water in the cylinder to the level of precision permitted by the calibration marks on the barrel of the cylinder. Calculate the density of the water. Compare the measured density of the water with the value listed in the back of the lab manual for the temperature of your experiment. Clean and dry the graduated cylinder when you finish using it. Obtain an unknown liquid and record its identification number. Determine the density of the unknown liquid, using the method just described for water.
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  • Fall '15
  • villareal
  • Chemistry, Sodium chloride, g/ml

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