Chem 207_Lab Report 1_Densities of Liquids and Solids 2

Chem 207_Lab Report 1_Densities of Liquids and Solids 2 -...

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Densities of Liquids and Solids Lab Instructor: Kaushik Nanda Chemistry 207 September 9, 2007
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Results and Discussion: Purpose : To experimentally determine the densities of an unknown solid and an unknown liquid as accurately and precisely as possible; to compare these experimental densities to theoretical density values in order to determine the identities of the solid and liquid samples. First, the density of water, a liquid of known density, was determined to ensure the accuracy of the experimental procedure. Three experimental trials were performed to ensure accuracy. The data and calculated values were tabulated (Table 1). Table 1: Mass of Water Data and Results Trial # Mass of Empty 25 mL Graduated Cylinder (g) Mass of 25 mL Cylinder and 10 mL H 2 O (g) Mass of H 2 O (g) 1 72.524 g 82.056 g 9.532 g 2 72.524 g 82.057 g 9.533 g 3 72.524 g 82.058 g 9.534 g The mass of water was calculated by subtracting the initial mass of the empty 25 mL graduated cylinder from the mass of the 25 mL cylinder plus 10 mL of water. An example of such a calculation using the Trial #1 data follows: (82.056 g H 2 O and cylinder) - 72.524 g cylinder = 9.532 g H 2 O The resulting mass values for water were used to calculate the experimental density of H 2 O (in g/mL). The data and calculated results were tabulated (Table 2). Table 2: Determining the Experimental Density of Water Data and Results Trial # Mass of H 2 O (g) Volume of H 2 O (mL) Density of H 2 O (g/ mL) 1 9.532 g 10.00 mL 0.9532 g 2 9.533 g 10.00 mL 0.9533 g 3 9.534 g 10.00 mL 0.9534 g The values for the density of water were calculated using the relationship between mass and volume. An example of such a calculation using Trial #1 data follows: Density = mass = 9.532 g H 2 O = .9532 g/mL H 2 O volume 10.00 mL H 2 O
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QuickTime and TIFF (Uncompressed) d are needed to see this p The average of these three determined density values for H 2 O, x = 0.9532 g/mL + 0.9533 g/mL + 0.9534 g/mL = 0.9533 g/mL 3 was considered to be the experimental density of water. Given the very small average deviation, ∆ x = ∆ x = |0.9533 g/mL - 0.9532 g/mL| + |0.9533 g/mL - 0.9533 g/mL| + |0.9533 g/mL - 0.9534 g/mL| = 3 = 6.667 x 10 -5 g/mL H 2 O and small relative average deviation, Relative average deviation = ∆ x (100) x Relative average deviation = 6.667 x 10 -5 g/mL H 2 O (100) = 0.006993% 0.9533 g/mL H 2 O of the calculated water density values, the results were determined to have a high degree of precision. Given the relatively small percent error compared to the theoretical water density value, Percent error = |accepted value – mean value | (100) | accepted value | Percent error = |1.000 g/mL H 2 O – 0.9533 g/mL H 2 O | (100) = 4.670% error | 1.000 g/mL H 2 O | the results were determined to contain an adequate degree of accuracy. Therefore, it was determined that the experimental procedure used to determine the density of water was both
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Chem 207_Lab Report 1_Densities of Liquids and Solids 2 -...

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