Forensics Name ___________________ Lab: Density Per ___ Due Date _________ Introduction Density is the ratio of an object's mass to its volume. • gold has a density of 19 g/mL mass
density
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• the average rock has a density of 3 g/mL volume
• water has a density of 1 g/mL What does g/mL mean? 1 g/mL means that 1 mL (or cm3) of the substance has a mass of 1 gram or 1 Liter of the substance has a mass of 1 kg. Objective You will be finding the density of a liquid and four solids. The masses will be found on a balance. The volumes will be calculated from the radius and the height or determined by submerging in water. Remember to read the volume of liquid in a graduated cylinder by reading the bottom of the meniscus as shown below. Pre‐lab Questions 1. Which is more dense, a marshmallow or hot chocolate? a) It depends on how much of each you have b) The marshmallow because it floats c) The hot chocolate because it is a liquid d) The marshmallow because it weighs 25g and the chocolate powder only 17 g 2. Which is more dense, water or oil? How do you know? 3. What mass will 3.0 mL of gold have? L_02x03_Density
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Procedure A – Liquid 1. Place a 10 mL graduated cylinder on the balance and record its mass in Table 1. 2. Put exactly 5 mL of the unknown liquid into the cylinder and find the combined mass of the cylinder and liquid. Record the mass in Table 1 (Trial 1). 3. Add exactly 5 mL more of the unknown liquid into the cylinder (for a total of 10 mL) and find the combined mass of the cylinder and liquid. Record the mass in Table 1 (Trial 2). 4. Switch to a 100 mL graduated cylinder and record its mass in Tab;e 1 (Trial 3). 5. Put exactly 50 mL of the unknown liquid into the cylinder and find the combined mass of the cylinder and liquid. Record the mass in Table 1 (Trial 3). 6. Calculate the density of the liquid (all trials). Show your work in the space provided. 7. Pour the unknown liquid back into its bottle when finished. Be sure to secure the cap tightly. Data Table 1 Determining the Density of a Liquid Liquid # ______ Measurement Trial 1 Trial 2 Trial 3 Mass of liquid & cylinder (g) Mass of cylinder (g) Mass of liquid (g) Volume of liquid (mL) Density of Liquid (g/mL) (Show all work; Circle your final answer) L_02x03_Density
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Procedure B – Regular Solid 1. Mass the rectangular solid and record the mass in Table 2. 2. Use a caliper to measure the length, width, and height of the cylinder. Record these measurements in Table 2. 3. The volume of a rectangular solid is calculated by the formula V = (L)(W)(H). Calculate the volume of the rectangular solid and record it in Table 2. 4. Calculate the density of the rectangular solid. Show your work in the space provided. 5. Repeat steps 1 – 4 for the second rectangular solid of the same substance Data Table 2 Determining the Density of a Regularly Shaped Solid Measurement Trial 1 Trial 2 Mass of rectangular solid (g) Length of rectangular solid (cm) Width of rectangular solid (cm) Height of rectangular solid (cm) Volume of rectangular solid (cm3) Density of rectangular solid (g/ cm3) (Show all work; Circle your final answer) L_02x03_Density
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Procedure C – Regular Solid 1. Mass the cylindrical solid and record the mass in Table 3. 2. Use a caliper to measure the height and diameter of the cylinder. Record these measurements in Table 3. 3. The volume of a cylinder is calculated by the formula V = π r2 h . Calculate the volume of the cylinder and record it in Table 3. 4. Calculate the density of the cylinder. Show your work in the space provided. 5. Repeat steps 1 – 4 for a second cylinder. Data Table 3 Determining the Density of a Regularly Shaped Solid Measurement Trial 1 Trial 2 Mass of cylinder (g) Height of cylinder (cm) Diameter of cylinder (cm) Radius of cylinder (cm) Volume of cylinder (cm3) Density of cylinder (g/ cm3) (Show all work; Circle your final answer) L_02x03_Density
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Procedure D – Regular, but Hollow, Solid 1. Mass the hollow cylindrical solid and record the mass in Table 4. 2. Use a caliper to measure the height and diameter of the outside of the cylinder. Record these measurements in Table 4. 3. The volume of a cylinder is calculated by the formula V = π r2 h . Calculate the volume of the entire cylinder and record it in Table 4. 4. Use a caliper to measure the inside diameter of the cylinder (that is, the cylinder of air inside the solid) 5. Calculate the volume of the cylinder of air. 6. Calculate the volume of substance by subtracting the air volume from the volume of the entire cylinder. 7. Calculate the density of the cylinder. Show your work in the space provided. 8. Repeat steps 1 – 7 for a second cylinder. Data Table 4 Determining the Density of a Regularly Shaped Solid Measurement Trial 1 Trial 2 Mass of cylinder (g) Height of cylinder (cm) Diameter of cylinder (cm) Radius of cylinder (cm) Volume of entire cylinder (cm3) Radius of cylinder of air (cm) Volume of cylinder of air (cm3) Volume of substance (cm3) Density of cylinder (g/ cm3) (Show all work; Circle your final answer) L_02x03_Density
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Procedure E – Irregular Solid 1. Mass the solid and record the mass in Table 5. 2. Place approximately 50 mL of water in a 100 mL graduated cylinder. Record the exact amount of water in Table 5. 3. Using a thread loop, slowly lower the irregular solid down into the cylinder of water. Record the combined volume of the object and water in Table 5. 4. Calculate the volume of the irregular solid. 5. Calculate the density of the irregular solid. Show your work in the space provided. 6. Repeat steps 1 – 6 for the second irregular solid. Data Table 5 Determining the Density of an Irregularly Shaped Solid Measurement Trial 1 Trial 2 Mass of solid (g) Volume of water and solid (mL) Volume of water (mL) Volume of solid (cm3) Density of solid (g/ cm3) (Show all work; Circle your final answer) L_02x03_Density
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Post‐Lab Questions 1. From the given list of possible unknowns, what was your unknown liquid in Part A? 2. What would be the mass of 100cm3 of the metal that the cylinder is made of? 3. Using a chart of the densities of common metals, what metal is the cylinder most likely made of? 4. If oil has a density of 0.88 g/cm3, would it float on the liquid used in this lab? Why or Why not? 5. Since a balance is much more accurate than a graduated cylinder, densities are found differently when an accurate answer is needed. A cylinder full of water is put on the balance and then the object is put in, causing some of the liquid to spill over. Then the cylinder, object, and water (minus the spill‐over) are massed. The volume of the object can then be calculated accurately. Use the following worksheet and data to find the density of the unknown. Remember that the density of water is 1.000 g/cm3. Worksheet 1 Mass of cylinder & water 201.051 g
Mass of object Expected mass of cylinder, water, object Mass of cylinder,water,object after spill over Mass of water spilled Volume of water spilled Volume of object Density of object L_02x03_Density
15.211 g
g
212.219 g
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mL
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g/ cm3
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