EXPERIMENT #2: DENSITY



SUNY OLD WESTBURY CHEMISTRY / PHYSICS DEPARTMENT PRINCIPLES OF CHEMISTRY EXPERIMENT #2: DENSITYObjectives To determine the density of an object with an irregular shape using the definition of density d = m ÷ V, and the water displacement method. Introduction The density of a substance is defined as its mass per unit volume (Density= MassVolume).Density is usually expressed in grams per cubic centimeter for solids and grams per milliliter for liquids. Density of a liquid or a solid can be used to identify substances. For solids with regular shapes, mass and volume can be evaluated by direct measurement, e.g., using an analytical balance and a ruler, respectively. The density is then calculated by dividing the object's mass by its volume. However, it is often difficult to measure the volume of an irregularly shaped object by using geometry. In this case, water displacement is an alternative method – submerge the object in water and determine its volume by the increase in volume observed. LAB REPORTThis is a project lab. Use any sources necessary to design your own lab procedure and data.Fill in Table 1 with your data. Include introduction, experimental procedure, data, calculations, sources of error, and conclusions in your lab report. If you use U.S. quarter dollars as your object, each quarter weighs 5.670 grams according to the U.S. Mint (). Lab Kit for Density DeterminationFour measurements need to be made. Look for these items and fill out the equipment form. Use your answers on the form to write your lab report. Link to Lab Kit Equipment formlengthvolumemasstemperatureDensity Data by the Method of Water Volume (Archimedes' Method)Table 1: Volume by Displacement Trial 1Trial 2Trial 3Description of objectMass of object, gVolume of water without object, mLVolume of water with object, mLVolume of object, mLDensity of object, g/mLAverage density, g/mLS.D., g/mLR.S.D.Density Determination by calculation of Volume Method of Water Displacement (Archimedes' Method)Table 1: Volume by Displacement Trial 1Trial 2Trial 3Description of objectMass of object in g, oz, or lbDimensions of object in in, cm, or mm):Name of dimension: Name of dimension:Name of Dimension:Calculated volume of object, mLDensity of object, g/mLAverage density, g/mLS.D., g/mLR.S.D.15674715875Shaded data must be recorded during labShaded data must be recorded during lab155643120555Unshaded data require calculation and/or justification post-lab0Unshaded data require calculation and/or justification post-labIf you use quarter dollars, compare your experimental volume for one quarter to the calculated volume per quarter using the formula for the volume of a cylinder = ?r2h. Diameter of quarter = 24.26 mm, thickness of quarter = 1.75 mm. If you use other coins, look up or measure the diameter and thickness to do the calculation. U.S. quarters prior to 1965 are 90% silver and 10% copper. Quarters from 1965 onward are 91.67% copper and 8.33% nickel. Look up the density of the metals in your quarters, and calculate the density of your quarters using the percent of each metal in your quarters. Calculate the percent error in your experimental data using the density calculated by the percent of each metal as the true density value. Why do you think the U.S. and other countries stopped using silver in quarters? ................
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